Factors that promote or hinder physical activity participation in patients with colorectal cancer: A systematic review

 ©Psy,Soc,&Educ,2017,Vol.9(2)  © Psychology, Society, & Education, 2017. Vol. 9(2), pp. 201-226 ISSN 2171-2085 (print) / ISSN 1989-709X (online) Doi10.25115/psye.v9i2.698 Factors that promote or hinder physical activity participation in patients with colorectal cancer: A systematic review María ROMERO-ELÍAS, David GONZÁLEZ-CUTRE, Vicente J. BELTRÁN-CARRILLO and Eduardo CERVELLÓ Sport Research Center, Miguel Hernández University of Elche, Spain (Received on March 22, 2017; Accepted on April 16, 2017) ABSTRACT:Different studies of patients with colorectal cancer have shown that physical activity has positive physical and psychosocial effects. However, most patients do not comply with the recommended criteria of physical activity. The aim of the present study was to analyze, by means of a systematic review of the literature, the factors associated with physical activity participation in patients with colorectal cancer. For this purpose, we conducted a search in the databases WEB OF SCIENCE, SCOPUS and SPORTDISCUS up to February of 2016. After the selection process, 23 full-text articles were retained. The results allowed identifying four large categories of factors related to physical activity participation in this population: sociodemographic factors, health factors (specific and nonspecific to the disease), prior experience and preferences, and motivational factors. Among the results obtained, comorbidity and the receipt of adjuvant therapy (with its corresponding side effects, such as fatigue and nausea) were related to less physical activity. Variables such as positive attitude, family support, satisfaction of basic psychological needs, and self-determined motivation were shown to be facilitators of physical activity. Taking into account these results, it is necessary to develop programs of physical activity adapted to the particular characteristics of this population and based on motivational strategies that promote adherence to physical activity. Keywords: physical exercise, motivation, barriers, treatment, health Factores que promueven o dificultan la práctica de actividad física en pacientes con cáncer colorrectal: Una revisión sistemática RESUMEN: Diferentes estudios con pacientes de cáncer colorrectal han demostrado que el ejercicio físico tiene efectos físicos y psicosociales positivos. Sin embargo, la mayoría de pacientes no cumple los criterios de actividad física recomendados. El objetivo del presente estudio fue analizar, a través de una revisión sistemática de la literatura, los factores asociados con la práctica de actividad física en pacientes con cáncer colorrectal. Para ello se realizó una búsqueda en las bases de datos WEB OF SCIENCE, SCOPUS y SPORTDISCUS hasta febrero de 2016. Tras el proceso de selección, se retuvieron 23 artículos a texto completo. Los resultados permitieron identificar cuatro grandes categorías de factores relacionados con la práctica de actividad física en esta población: factores sociodemográficos, factores de salud (específicos y no específicos de la enfermedad), preferencias y experiencias previas, y factores motivacionales. Entre los resultados obtenidos, cabe destacar que la comorbilidad y la recepción de terapia adyuvante (con sus correspondientes efectos secundarios como Physical activity in patients with colorectal cancer  ©Psy,Soc,&Educ,2017,Vol.9(2)  202 fatiga y náuseas), se relacionaron con una menor realización de actividad física. Variables como la actitud positiva, el apoyo familiar, la satisfacción de las necesidades psicológicas básicas y la motivación autodeterminada, se mostraron como facilitadores de la participación en actividad física. Teniendo en cuenta estos resultados, es necesario desarrollar programas de actividad física ajustados a las características particulares de esta población y basados en estrategias motivacionales que favorezcan la adherencia a la práctica. Palabras clave: ejercicio físico, motivación, barreras, tratamiento, salud. Correspondence: David González-Cutre, Centro de Investigación del Deporte, Universidad Miguel Hernández de Elche, Avenida de la Universidad s/n, 03202 Elche (Alicante). E-mail: dgonzalez- [email protected] INTRODUCTION Cancer is currently one of the major causes of mortality worldwide. In 2012, there were about 14 million new cases and 8.2 million cancer-related deaths (WHO, 2015). For example, cancer represents the second cause of death in the United States and is expected to exceed cardiovascular disease as the leading cause of death in the coming years (Siegel, Miller, & Jemal, 2015). It was estimated that 595690 Americans would die of cancer in 2016, which translates into about 1630 people per day (American Cancer Society, 2016). In Spain, the estimation 2015 was of 227076 cases, with an increase that occurs to a greater extent in the population ≥ 65 years (Spanish Society of Medical Oncology, 2014). Approximately 30% of cancer deaths are related to five behavioral risk factors: high body mass index, low intake of fruit and vegetables, smoking, alcohol consumption, and lack of physical activity (WHO, 2015). Besides the human suffering involved in cancer, it has been estimated that this disease causes a high economic cost for health systems. For example, the total cost of cancer in 2008 in the United States was around $ 228 billion. This situation is a serious public health problem, such that research of the factors that can prevent or alleviate the disease is a priority for governments (American Cancer Society, 2010). Specifically, in the United States, colorectal cancer is the third cause of death by cancer in men and women, and the second cause when both sexes are combined. In Europe, colorectal cancer held the second position in incidence after breast cancer in 2012, and 49190 deaths from colorectal cancer were estimated in 2016 (Spanish Network of Cancer Registers, 2014). Five to ten-year survival rates for patients with colorectal cancer are 65% and 58%, respectively (Siegel et al., 2015). Due to colorectal cancer, patients live with physical and psychological sequelae that grow worse with treatment. Some of the symptoms are: intestinal dysfunction, surgery pain, stoma, fatigue, muscle weakness, alteration of body image, anxiety, and depression (Downing et al., 2015; Zabora, BrintzenhofeSzoc, Curbov, Hooker, & Piantadosi, 2001). To alleviate these sequelae, there is increasingly more scientific evidence of the physical and psychological benefits of physical activity, both during and after treatment for this disease (Garcia & Thomson, 2014). Specifically, in colorectal cancer, it was found that regular exercise and Physical activity in patients with colorectal cancer ©Psy,Soc,&Educ,2017,Vol.9(2)  203 improved physical condition are associated with many indicators of quality of life (Courneya, Friedenreich, Arthur, & Bobick, 1999a; Courneya et al., 2004; Courneya, Mackey, & Jones, 2000), with a lower probability of recurrence (Meyerhardt, Heseltine et al., 2006) and lower risk of death (Meyerhardt et al., 2008). In the study of Meyerhardt, Heseltine et al. (2006), it was found that patients who walked at least 6 hours per week at moderate intensity had a 47% higher chance of surviving the disease. Another study (Meyerhardt, Giovannucci et al., 2006) with 600 women diagnosed with colorectal cancer showed that those who increased their physical exercise after diagnosis had a 52% lower chance of dying from the disease compared with those who were not exercising. However, those who decreased the amount of exercise had a 32% higher chance of dying from the disease. Moreover, those who did physical exercise equivalent to walking 6 hours per week were more likely to have a longer life than those who did less or no exercise. In spite of the described benefits, only 35% of colorectal cancer survivors in the United States perform the recommended physical activity (Blanchard, Courneya, & Stein, 2008), and 17.1% in Canada (Courneya, Katzmarzyk, & Bacon, 2008). In addition, various studies carried out in Canada (see Vallance & Courneya, 2012) show that, after diagnosis, physical activity decreases on average about 2 hours per week, and only 5-10% of the patients participate in physical activity during treatment, and 20-30% after treatment. After overcoming the disease, patients increase their physical activity participation but without reaching the initial levels. There is also a greater decrease of physical activity when combining various treatments such as surgery, chemotherapy, and radiotherapy, in comparison to receiving just one of them (Irwin et al., 2004). However, 80% of the patients feel capable of participating in physical activity, and 70% are interested in it so, in order to develop any intervention, it is essential to know the factors that promote or hinder physical activity participation in this collective (Vallance & Courneya, 2012). Taking into account that there are already plenty of studies that have analyzed this problem in colorectal cancer patients, the aim of this study was to perform a systematic review to more clearly interpret all the factors related to these patients' participation in physical activity. There are several systematic reviews of the factors related to the physical activity participation in patients with cancer, all of them including different types of cancer (Park & Gaffey, 2007). Some authors have even systematically analyzed the effects of exercise in patients with colorectal cancer (Cramer, Lauche, Klose, Dobos, & Langhorst, 2014; Kampshoff et al., 2014; Husebø, Dyrstad, Søreide, & Bru, 2013). However, to date there is no systematic review of the factors associated with physical activity participation in patients with colorectal cancer, so this is the first one to be performed. This review is focused on colorectal cancer because it is the second most common type of cancer in Europe and the United States, and the most frequent in some countries like Spain (Spanish Society of Medical Oncology, 2014), presenting a moderate survival rate. Given its high incidence, but at the same time its positive prognosis, we think that it is interesting to focus on this type of cancer to more specifically deepen our knowledge of the factors related to the levels of physical activity. In addition, the variables contributing to predict physical activity Physical activity in patients with colorectal cancer  ©Psy,Soc,&Educ,2017,Vol.9(2)  204 appear to vary as a function of the type of cancer, which indicates the need to analyze each one separately (Vallance & Courneya, 2012). METHOD Data sources and search terms The electronic search was made by means of the WEB OF SCIENCE, SCOPUS and SPORTDISCUS databases up to February of 2016. The searches included diverse combinations of four sets of terms: 1) Terms related to cancer: colorectal cancer, cancer stage and treatment; (2) Terms about physical activity: physical activity, exercise and training; 3) Influential factors in physical activity participation: facilitators, barriers, sociodemographic and psychosocial factors, motivation and adherence; 4) Motivational theories: theory of planned behavior, self-determination theory, self-efficacy theory, and socio-ecological model. The complete search strategies are not presented for the sake of brevity, but they can be requested from the authors. Consultation of publications and construction of the catalogue The selection of the studies focused on the factors associated with physical activity participation in patients with colorectal cancer (Figure 1). We conducted two levels of screening. First, we searched for combinations of all the keywords in all the databases, reaching 19213 identified registers. Another 18 additional registers were identified in the references lists of the articles, obtaining a total of 19231 recordings. We included all the references in the program “EndNote” to detect duplicates, finding a total of 15532, which were deleted. Therefore, 3699 unique citations remained, from which we excluded 3649 after reading the abstracts because they did not analyze the relations between physical activity participation and colorectal cancer, so that finally, 50 articles remained, which were downloaded in full text. We then established the second screening system, which consisted of applying the following exclusion criteria: 1) including other different types of cancer without specifying the results separately for each one; (2) including other healthy behaviors without specifying the results referred to physical activity; 3) focusing on factors or strategies to promote physical activity in order to prevent colorectal cancer, but without using a sample of patients affected with this disease; 4) focusing only on the effects or benefits of physical activity in this population without covering the factors related to physical activity participation. We eliminated 27 registers for meeting these criteria, leaving a total of 23 final registers in the present study. Physical activity in patients with colorectal cancer ©Psy,Soc,&Educ,2017,Vol.9(2)  205 Figure 1. Flow chart of the selection process of the studies. Selection process and data extraction The necessary variables to analyze the results are grouped in Table 1. The following data are included: references; total number of patients, of men and women; age; cancer stage at the moment of the study; treatment; theoretical framework; design; measure of physical activity; and results related to the facilitators and barriers for physical activity participation. Cancer stage (see footnote of Table 1), type of treatment (surgery, radiotherapy, chemotherapy) and whether or not they were receiving treatment at the time of the study or it had already concluded were included in this review. In addition, we indicate the design of the studies, dividing them into cross-sectional, longitudinal, experimental, and qualitative. We also aimed to identify whether the studies are supported by a theoretical framework, as this would guide interventions to promote physical activity with this collective in a more structured way, understanding how behavioral change occurs (Biddle, Mutrie, Gorely, & Blamey, 2012). Lastly, we highlight the importance of analyzing how physical activity is measured, either by means of more subjective measures like questionnaires, or more objective measures like accelerometers. All these aspects are important when analyzing the factors that influence physical activity participation in this population. 19213 studies identified for screening 18 additional registers identified from other sources 15532 duplicate events 3699 unique registers identified 3649 excluded registers 27 full-text registers excluded: They include other different types of cancer without specifying the results for each type. n = 14 They include other healthy behaviors without specifying the results referring to physical activity.n = 6 Studies of prevention of cancer by means of physical activity, but without using a sample of patients with this disease. n = 5 They focus on the effects/benefits of physical activity in this population but without including the factors related to its p artici p ation. n= 2 50 full-text articles analyzed to decide their eligibility 23 studies included in the systematic review Physical activity in patients with colorectal cancer  ©Psy,Soc,&Educ,2017,Vol.9(2)  206 Table 1. Studies that Analyze the Factors Related to Physical Activity Participation in Patients with Colorectal Cancer REFERENCES NUMBER OF PATIENTS AGE (years) CANCER STAGE TREATMENT THEORETICAL FRAMEWORK DESIGN MEASURE OF PA RESULTS Buffart et al. (2012) 1371 Total 56% males 44% females ≥ 65 = 69% M = 69.5, SD = 9.7 I = 28% II = 39% III = 28% IV = 5% S = 67.54% RT = 0.07% CT = 1.02% S + RT = 22.90% S + CT = 24.58% S + RT + CT = 6.41% Not used Crosssectional European Prospective Investigation into Cancer (EPIC) Physical Activity Questionnaire Being younger, male, employed, not smoking, lower body mass index, being only in chemotherapy treatment and not having comorbidities→↑MVPA Chambers et al. (2009) 978 Total 55.8% males 44.2% females 20-49 = 7.6% 50-59 = 20.3% 60-69 = 35% ≥ 70 = 37.2% I = 28.7% II = 30.6% III = 25.8% IV = 0.7% Not specified Not used Longitudinal 5, 12, 24 and 36 months post diagnosis Active Australia Survey ↑Somatization →↓PA ↑Negative assessment of the impact of cancer →↓PA ↑Fatigue →↓PA ↑Smoking →↓PA ↑Obesity →↓PA Chung et al. (2013) 422 Total 63% males 37% females M = 59.69, SD = 10.87 I = 95 II = 102 III = 103 IV = 16 Unfinished = 31.27 % Finished = 68.72 % Not used Crosssectional Exercise & Quality of Life Questionnaire In treatment: Without changes in LPA, MPA and TPA. ↓VPA End of treatment: Without changes in MVPA vs. pretreatment.↑LPA and TPA Courneya et al. (1999b) 66 Total 57.57% males 42.42% females M = 60.8, SD = 11.5 I = 6% II = 29% III = 26% IV = 5% Did not receive AT = 27.3% RT = 7.6% CT = 46.9% RT + CT = 18% Theory of planned behavior Crosssectional Godin Leisure Time Exercise Questionnaire (GLEQ) Intention and pre-diagnosis PA →PA post operation Courneya et al. (2004) 102 Total 58.1% males 41.9% females M = 60.3, SD = 10.4 III–IV = 80.6% S = 100% RT = 20.4% CT = 64.5% Only S = 34.4% S + CT = 46.2% S + RT + CT = 19.4% All patients were operated in the past 3 months Theory of planned behavior Experimental Godin Leisure Time Exercise Questionnaire (GLEQ) Experimental group: Higher levels of PA, behavioral control, lower work status, and less adjuvant treatment →↑PA Control group: higher levels of PA and more intention →↑PA Courneya et al. (2005) 69 Total 56.5% males 43.5% females < 60 = 39.1% > 60 = 60.9% Not specified Only S = 39.1% S + CT = 42% S + RT + CT = 18.8% All patients were operated in the past 3 months Not used Experimental Godin Leisure Time Exercise Questionnaire (GLEQ) Barriers: Lack of time,adjuvant treatment, side effects and fatigue Physical activity in patients with colorectal cancer ©Psy,Soc,&Educ,2017,Vol.9(2)  207 D’Andrea et al. (2014) 2378 Total 18-65 Not specified Not specified Not used Crosssectional USA National Health Interview Survey Hispanics and non-Hispanic blacks (vs. Whites) and current smokers →↓PA Higher educational level, fewer chronic conditions, current drinkers →↑PA Dennis et al. (2013) 444 Total 55% males 45% females 36-91 (M = 69) ≥ 60 = 80% Not specified Pre-treatment = 12.16% In treatment = 13.96% Completed 6 months ago = 15.09% Completed more than 6 months ago = 40.1% Cancer-free group = 18.69% Not used Crosssectional Lifestyle survey for people with colorectal cancer Preferences: Group-based PA programs Barriers: Stoma and treatmentrelated fatigue VPA (from - to +): Pre-treatment, in treatment, post-treatment, < 6 months and > of 6 months posttreatment and cancer-free group Fisher et al. (2016) 478 Total 59% males 41% females 31-97 (M = 68) Not specified Finished = 73% Not finished = 16% Unknown = 5% Not used Crosssectional Godin Leisure Time Exercise Questionnaire (GLEQ) Barriers: Fatigue, ageing, and comorbidities ↑Barriers →↓PA Benefits: improvement of physical condition, improvement of health and maintenance/weight loss Hawkes et al. (2015) 410 Total 54% males 46% females M = 66.3, SD = 10.1 Insufficient PA I = 90.2% II = 85.1% III = 89.1% Sufficient PA I = 9.8% II = 14.9% III = 10.9% S = 96% AT = 24% Ecological model of health behavior Experimental Godin Leisure Time Exercise Questionnaire (GLEQ) Being retired, having private health insurance, having healthy body weight, pre-diagnosis physical activity, having a habit, high level of self-efficacy, watching less TV, high quality of physical life, feeling well-being and being a part of the intervention group →↑PA post 12 months Husson et al. (2015) 1643 Total 56.11% males 43.88% females < 65 = 28.97% 65-75 = 39.07% > 75 = 31.96% I = 30.66% II = 36.33% III = 29.66% IV = 3% Only S = 46.33% S + RT = 24.33% S + CT = 20.66% S + RT + CT = 8.66% Only CT = 1.33% Not used Longitudinal European Prospective Investigation Into Cancer (EPIC) PA Questionnaire ↓Knowledge about health →↓PA Kang et al. (2014) 427 Total 63% males 37% females < 60 = 52.9% ≥ 60 = 47.1% I = 95 II = 102 III = 106 IV = 18 Unfinished = 30.9% Finished = 67% Not used Crosssectional Question about participation or not in PA and whether or not recommendations of the ACSM are met Barriers (from + to -): 1st Fatigue 2nd Low physical condition 3rd Low health status 4th Lack of time and information ↑Treatment →↓PA Physical activity in patients with colorectal cancer  ©Psy,Soc,&Educ,2017,Vol.9(2)  208 Lynch et al. (2016) 185 Total 55.14% males 44.86% females 18-80 (M = 64.2, SD = 10.3) I = 22% II = 28% III = 41% Only S = 57.84% S + AT = 42.16% Adjuvant therapy finished Not used Crosssectional Accelerometer Males, more comorbidities, higher BMI and time slot 6 pm-8 pm →↑Sedentary behavior Women, low educational level and lower BMI →↑LPA More family income, being employed, lower BMI, younger, and time slots 4 pm-5 pm and 6 pm10 pm →↑MVPA Lynch et al. (2007) 1966 Total 60% males 40% females 20-49 = 8.5% 50-59 = 19.43% 60-69 = 33.31% 70-80 = 38.25% Not specified Not specified Not used Longitudinal Active Australia Survey High educational level, no smoking, no fatigue →↑PA in males Only surgery, healthy BMI, living outside the capital, no smoking, no fatigue →↑PA in women Lynch et al. (2010) Time 1 538 Total 63% males 37% females Time 2 403 Total 61.5% males 38.5% females Time 1 20-49 = 8.9% 50-59 = 19.7% 60-69 = 31.1% ≥ 70 = 40.3% Time 2 20-49 = 8.9% 50-59 = 19.4% 60-69 = 29.0% ≥ 70 = 42.7% Time 1 I = 25.5% II = 35% III = 30.6% IV = 8.9% Time 2 I = 26% II = 38% III = 29.4% IV = 7.1% Time 1 S = 56.9% S + AT = 43.1% Time 2 S = 58% S + AT = 41.4% All the patients were operated in the past 3 months Ecological model of health behavior Longitudinal 5 and 12 months postdiagnosis Not measured Barriers 5 and 12 months (from + to -): 1st Cancer-specific barriers 2nd Barriers from personal attributes 3rd Barriers from social environment 4th Barriers from physical environment McGowan, SpeedAndrews, Blanchard et al. (2013) 600 Total 58.33% males 41.67% females < 65 = 39% ≥ 65 = 61% 44% Early stage diagnosis RT = 24% 10% still receive treatment Not used Crosssectional Godin Leisure Time Exercise Questionnaire (GLEQ) Older, lower educational level, lower yearly income, more time elapsed since diagnosis, fewer relapses, stoma, in treatment and active vs. sedentary → ↓ interest in PA McGowan, SpeedAndrews, Rhodes et al. (2013) 600 Total 58.3% males 41.7% females < 65 = 39% ≥ 65 = 61% M = 67.3 I = 12.6% II = 11.5% III = 21.5% IV = 11.33% Unknown = 43% RT = 24.3% CT = 55.5% Not specified when they received treatment Not used Crosssectional Questions about type, frequency, and duration of PA in the past month Males, married, social or regular drinkers, good health and ≥ 5 years since the diagnosis →↑PA Morielli et al. (2016) 18 Total 66.7% males 33.3% females 34-73 (M = 57.5) 72% IIIB All received neoadjuvant therapy Theory of planned behavior Experimental Godin Leisure Time Exercise Questionnaire (GLEQ) Benefits: cardiovascular endurance, quality of life, self-esteem, better physical functioning Damage: Fatigue, diarrhea, and skin irritation Barriers: Side effects of neoadjuvant therapy and lack of motivation Physical activity in patients with colorectal cancer ©Psy,Soc,&Educ,2017,Vol.9(2)  209 Peddle et al. (2008) 413 Total 54% males 46% females 20-80 (M = 60, SD = 7.5) 48% did not know cancer stage. Nothing more specified CT = 53%. At least 1 year ago S = 96%. Not specified when they were operated Selfdetermination theory Crosssectional Godin Leisure Time Exercise Questionnaire (GLEQ) ↑Educational level, identified and introjected regulation →↑PA Speed-Andrews et al. (2014) 600 Total 58.3% males 41.7% females 31-92 (M = 67.3) 44.2% Early stage diagnosis RT = 24% CT = 55% Adjuvant therapy completed Theory of planned behavior Crosssectional Question about level of physical activity Barriers: physical condition and health status, musculoskeletal issues and treatment Facilitators: having time, doing it with others, proximity to the facilities Speed-Andrews et al. (2012) 600 Total 58.33% males 41.67% females 31-92 (M = 67.3) < 65 = 39% ≥ 65 = 61% I = 12.66% II = 11.5% III = 21.5% IV = 11.33% Unknown = 43% RT = 24.3% CT = 55.5% Adjuvant therapy completed Theory of planned behavior Crosssectional Godin Leisure Time Exercise Questionnaire (GLEQ) Being younger, unmarried, higher educational and economic level, employed, not smokers, social drinkers, no radiation therapy, disease free, better health and fewer comorbidities →↑PA Spence et al. (2011) 10 Total 70% males 30% females 42-74 (M = 57.8) II = 40% III = 60% Chemotherapy completed 4 weeks ago Not used Experimental Qualitative Questions about the level of physical activity: nothing, sporadic (< 3 sessions per week) or regular (≥ 3 sessions per week) Benefits: Self-esteem, healthy habits, positivity, intention to perform PA, learning about the importance of PA, physical condition, recovering levels of energy prior to treatment and decreasing fatigue. Preferences: Need for trainer supervision. Start PA 2-4 weeks post-treatment, but can also be done during treatment, decreasing the intensity. Post-program PA: introduce strength training and everyone intends to continue. van Putten et al. (2016) 5375 Total Time 1 = 45.6% of the total Time 2 = 29.32% of the total Time 3 = 25.58% of the total 54.6% males 45.5% females < 55 = 7.6% 55-74 = 60% ≥ 75 = 32.4% M = 69.6, SD = 9.5 I = 31.8% II = 38.6% III = 29.5% Only S = 49.6% S + RT= 23.1% CT= 20.3% S + RT + CT = 7% Not used Longitudinal European Prospective Investigation into Cancer (EPIC) Physical Activity Questionnaire Fatigue, dyspnea, side effects of chemotherapy, urination problems, loss of appetite, weight loss, pain, not so young, without partner, obesity, anxiety, depression, worse quality of life and physical functioning→ ↓MVPA ↑PA males vs. women Note. ↑ = increase; ↓ = decrease; → = relation; AT = adjuvant therapy; S = surgery; RT = radiotherapy; CT = chemotherapy; PA = physical activity; LPA = light physical activity; MPA = moderate physical activity; VPA = vigorous physical activity; MVPA = moderate and vigorous physical activity; TPA = total physical activity. Stage I: the tumor affects the wall of the colon or rectum without going through the muscular layer. Lymph ganglia not affected. Stage II: the tumor has infiltrated all the layers of the wall of the colon or rectum. It can invade the surrounding organs. Lymph nodes not observably affected. Stage III: the cancer has invaded the neighboring organs and affects the lymph nodes. Stage IV: the cancer has spread to distant organs of the colon or rectum, such as liver, lung or bones. Physical activity in patients with colorectal cancer  ©Psy,Soc,&Educ,2017,Vol.9(2)  216 Regarding time schedule preferences for physical activity in colorectal cancer patients, a study in Australia and Canada, measuring the levels of activity with accelerometers, has recently been carried out (Lynch et al., 2016). The results showed that the patients were less sedentary from eight in the morning until three in the afternoon and more sedentary from six in the afternoon. The percentage of time performing moderate-vigorous physical activity was lower between ten o'clock in the morning and three in the afternoon and higher from four to ten in the afternoon. Lastly, Spence et al. (2011) carried out a study in Australia, analyzing patients' preferences after chemotherapy by means of semistructured interviews. The patients preferred to choose the type of exercise and a gym with air conditioning to regulate body temperature and be able to make more effort without suffering from the heat. They also preferred to start the physical activity program between 2 and 4 weeks after completing chemotherapy because they thought they needed time to recover from it. However, some preferred to start later but to maintain contact with the hospital during this time of recovery after chemotherapy, so as not to lose their motivation and commitment to the program. On another hand, half of the patients claimed that they could have started the program during the adjuvant treatment but decreasing the intensity. In contrast, the other half said that this would be very difficult due to the fatigue caused by the treatment and the physical and emotional energy required to overcome these symptoms. However, almost everyone believed that if they had performed exercise during treatment, they would have felt better when the treatment was finished. In this study, the patients also positively valued the supervised individualized training, adapted to their characteristics, being able to choose the schedule, place, type of session, etc. In fact, they expressed difficulty to continue the physical activity program without the trainer's support and follow-up. They all considered the trainer's supervision necessary to achieve greater motivation and increase their levels of self-confidence. Concerning group physical activity, they thought that it would be more economical, they would have more social support, and would share experiences. However, most preferred to carry out the physical activity program individually and, if it was done in a group, they preferred their classmates to be cancer survivors or people whose life had recently been at risk. Lastly, after the program, all the participants intended to continue doing physical activity and proposed to include strength training and to maintain the level of aerobic exercise. They pointed out that it would be difficult to continue the frequency and the intensity of the workouts without the supervision of the trainer. Motivational factors Next, we present the factors associated with the motivational theories that explain human behavior, trying to understand which variables are related to the physical activity participation in this population. On the one hand, some studies have found higher levels of perceived selfefficacy in patients who perform more physical activity (Hawkes et al., 2015). On the other hand, based on the theory of planned behavior, Courneya et al. (1999b) found that the intention to exercise and exercise pre-diagnosis were related to post-surgery exercise. Moreover, the attitude towards exercise was the only variable that correlated significantly with the intention to Physical activity in patients with colorectal cancer ©Psy,Soc,&Educ,2017,Vol.9(2)  217 exercise. From this same theory, Morielli et al. (2016), trying to understand the influence of prior expectations before the physical activity program, revealed that patients perceived exercise during chemotherapy as more pleasant and less difficult than anticipated. Continuing with the theory of planned behavior, among the most frequent beliefs about the benefits of physical activity (behavioral beliefs), Speed-Andrews et al. (2014) found that patients believed that physical activity improved physical fitness, it could improve their wellbeing and energy levels, and they felt better after exercising. With regard to normative beliefs, the most common belief was that physical activity should be approved by the members of the family, the oncologists, and one's best friend. As regards control beliefs, the factors that made them feel less confident of being able to overcome barriers were medical or health problems, pain, and the fact of returning to treatment (Speed-Andrews et al., 2014). In this sense, Courneya et al. (2004) found that patients who perceived less behavioral control, that is, they felt less capable of carrying out activity, showed less adherence to physical activity. Using the ecological model of health behavior as the conceptual reference framework, Lynch et al. (2010) found that disease-specific barriers (fatigue, not feeling well enough to be physically active, diarrhea, and incontinence) and personal attributes (fear of injury, lack of enjoyment and interest, and being sedentary) were the greatest barriers both at five and at twelve months after diagnosis, followed by social environment (lack of time, not having the support of family, friends, and doctor) and physical environment (lack of access to facilities, the center perceived as unsafe and unattractive). All of these barriers were negatively related to participation in physical activity, except for the disease-specific barriers. Contrary to expectations, participants who showed a higher level of physical activity twelve months after diagnosis also had a greater number or intensity of disease-specific barriers. Perhaps the symptoms and side effects of the disease and treatment had decreased in general in this population, but they were more evident among those who submitted their body to a greater physical burden by exercising. Lastly, Peddle et al. (2008) analyzed the factors that influenced physical activity participation in these patients from self-determination theory. The results showed that perceived autonomy support in close people was positively linked to satisfaction of the needs for autonomy, competence, and relatedness, and with identified regulation (a kind of motivation characterized by valuing the benefits of an activity). Relatedness positively predicted identified regulation and introjected regulation (a kind of motivation characterized by a feeling of guilt), autonomy positively predicted introjected regulation, and perceived competence positively predicted identified regulation. Both identified regulation and introjected regulation positively predicted physical activity. DISCUSSION AND CONCLUSIONS The aim of this study was to provide a global view of the factors that facilitate or hinder the physical activity participation in patients with colorectal cancer by means of a systematic review of the literature. This is the first systematic review that specifically analyzes these factors in colorectal cancer. From all the information collected in this review, we reached Physical activity in patients with colorectal cancer  ©Psy,Soc,&Educ,2017,Vol.9(2)  218 various conclusions that will allow us to establish recommendations for the promotion of physical activity in this population. First, among the sociodemographic factors, the following favor participation in physical activity in patients with colorectal cancer: being male, white, younger, higher educational level and higher economic status, having a job that does not involve a very extensive work schedule, having less occupational experience, or being retired. However, some contradictory results emerge when analyzing the influence of marital status and personal relationships on physical activity. Speed-Andrews et al. (2012) found that being single is related to doing more physical activity, whereas van Putten et al. (2016) found that having a couple relationship favors the participation in moderate and vigorous physical activity. It is true that conjugal obligations can cause people to have less time to do physical activity, but the partner's support to carry out physical activity during the disease seems essential (Mackenzie, 2015). With regard to health factors non-specific to the disease, we can conclude that obese patients perform less total physical activity, while patients with lower body mass index perform more moderate and vigorous physical activity. In addition, patients who are overweight or obese perceive surgical complications as barriers to exercise to a greater extent. Among the factors associated with psychological well-being, patients with more stress, anxiety, and depression perform less physical activity whereas those who have better quality of life and physical functioning participate more. Regarding disease-specific health factors, patients who are not receiving adjuvant treatment, have fewer comorbidities, and perceive better quality of life perform more physical activity. During treatment, patients perceive more barriers to exercise related to the side effects, such as fatigue, diarrhea, or skin irritation (Morielli et al., 2016). Although in general, receiving adjuvant treatment hinders physical activity participation, one study (Buffart et al., 2012) found that chemotherapy was a predictor of moderate and vigorous physical activity. The authors of this study try to explain this result arguing that the patients who received chemotherapy were the healthiest, the youngest, and with fewer comorbidities, and perhaps they also received more advice about physical activity to alleviate the side effects of chemotherapy. Considering the influence of prior experience and preferences on physical activity, we find that the patients who exercised the most were those who performed physical activity before diagnosis (McGowan, Speed-Andrews, Blanchard et al., 2013). Thus, lack of time was only a drawback for those patients who did not exercise before diagnosis. Moreover, most of the patients felt capable of doing physical activity, they preferred to receive information about physical activity after diagnosis through the personal advice of a fitness expert, and preferred to participate in group-based physical activity programs. Nevertheless, it should be highlighted that patients with a stoma showed less preference for group participation in a fitness center. Having access to facilities was also a relevant factor for physical activity participation (Speed Andrews et al., 2014), and walking was the favorite physical activity both in summer and in winter (McGowan, Speed-Andrews, Blanchard et al., 2013). This result could be due to the fact that walking is a simple and accessible activity, it does not imply any cost and does not require Physical activity in patients with colorectal cancer ©Psy,Soc,&Educ,2017,Vol.9(2)  219 much knowledge about methods of physical training. However, some activities could be more recommendable to achieve greater levels of intensity that translate into greater benefits. As pointed out in the literature, physical activity decreases during and after treatment in spite of the fact that 150 minutes per week of moderate activity, or 75 minutes of vigorous activity, or an equivalent combination are recommended (Rock et al., 2012; Schmitz et al., 2010). In this regard, it is likely that patients do not know what other activities they can carry out, and specific programs for this type of patients are probably not provided in fitness centers. Patients were less sedentary from eight in the morning until three in the afternoon and more sedentary from six in the afternoon, reaching higher levels of vigorous physical activity from four to ten in the afternoon (Lynch et al., 2016). Learning more about the variability of physical activity patterns at different moments of the day may be helpful to consider more appropriate strategies to promote physical activity. In the following section, we propose some recommendations from this evidence. Lastly, we will discuss the motivational factors related to physical activity behavior in these patients. According to the theory of planned behavior, the attitude towards exercise was the only variable that was related to the intention to exercise, which in turn, was linked to performing more post-surgery physical activity (Courneya et al., 1999b). With regard to beliefs (Speed-Andrews et al., 2014), thinking that physical activity would improve one's physical condition, energy level, and well-being was associated with performing more physical activity. In addition, the patients thought that physical activity should be supported by relatives, friends, and doctors. Lastly, medical or health problems, pain, and relapse and return to treatment, were the most frequently reported control beliefs that hindered physical activity participation. Based on self-determination theory, one study showed that autonomy support, satisfaction of the three basic psychological needs (autonomy, competence and relatedness), and identified and introjected regulations were important variables for physical activity participation in patients with colorectal cancer (Peddle et al., 2008). The results of this review have allowed us to sort and classify all the existing information on this topic to date. When designing physical activity programs for colorectal cancer patients, sociodemographic features, health factors, prior experience and preferences, as well as certain motivational factors should all be valued. The different conclusions reached should be taken into account for the development of physical activity in this population, considering the important benefits that can be achieved. RECOMMENDATIONS Drawing from the results obtained in this review, we present the following recommendations to promote physical activity in patients with colorectal cancer: 1) The existence of a less active profile in these patients, together with the physical and psychological side effects caused both by the disease itself and by the treatment, reveals the need to create specific programs of physical activity targeting this population, which contemplate their personal features. Special attention should be paid to the promotion of physical activity among older patients, women, and patients Physical activity in patients with colorectal cancer  ©Psy,Soc,&Educ,2017,Vol.9(2)  220 with lower socioeconomic status and educational level, because these sectors of the population are less interested in doing physical activity. 2) The programs should incorporate motivational strategies to foster a positive climate during the sessions of physical activity, ensuring that the participants feel respected and valued. Social environments should not only be inclusive but also the structure of the exercise facilities should favor the inclusion of patients with colorectal cancer. For example, the incorporation of showers and changing rooms that comply with the privacy of patients with a stoma, who may suffer from a problem related to body image, would be desirable. 3) It would be interesting to inform the patients about the benefits of physical activity for their disease, conducting seminars in the health centers. These seminars could include testimonials from patients who have already overcome the disease and who carried out physical activity during its course. This could improve patients' attitude towards physical activity and their intention to exercise. 4) Professionals from the sport sciences should be incorporated into the multidisciplinary medical team so that they could advise patients, recommend the best physical activity for each individual, and design individualized training programs. The competence of the professionals in charge of the direction of physical activity programs is essential because colorectal cancer patients are in a delicate health situation and need to be assured that their exercise will be carried out in conditions of safety to obtain the most benefits and take as few risks as possible. 5) If future studies with accelerometers confirm that patients with colorectal participate less in physical activity in the morning, programs of active rest during working hours could be designed, and active commuting for everyday trips could be fostered. Likewise, it would be interesting to develop physical activity programs in the afternoon time slots which patients usually dedicate to leisure. 6) Group activities to promote social relations among patients who are engaged in exercise programs could be designed, and also adapting the training loads to each person and offering autonomy. Thus, more self-determined motivation would be achieved and, thereby, more involvement and adherence to physical activity. To achieve these goals, it would also be necessary to promote patients' perception of competence, so they will feel capable to participate in physical activity programs. 7) Family, friends, health professionals, and other patients/peers should collaborate in the promotion of an active and healthy lifestyle in people suffering from colorectal cancer. Social support can be essential for these patients to acquire habits of physical activity that can contribute to alleviating the symptoms of their disease and to substantially improving their quality of life. LIMITATIONS OF THE LITERATURE AND FUTURE RESEARCH DIRECTIONS In spite of the results found in this review, we also identified important gaps in the literature that we shall detail in the following paragraphs. First, it should be noted that, out of all the reviewed articles, only 5 used an experimental design. There is still a lack of knowledge about the type, frequency, duration, and intensity of physical activity that are necessary to optimize Physical activity in patients with colorectal cancer ©Psy,Soc,&Educ,2017,Vol.9(2)  221 the physical and psychosocial benefits and reduce the risks in patients with colorectal cancer at different phases of treatment and as a function of the types of treatment. Increasing this knowledge is essential to improve the therapeutic effects of exercise and to promote physical activity participation in these patients. In addition, more studies are needed to implement and analyze the effect of strategies to motivate these patients to participate in physical activity. It is also necessary to highlight that only one study collected information by means of qualitative techniques. There is a lack of qualitative studies that analyze in depth the reasons that lead patients with colorectal cancer to participate in physical activity, as well as the barriers they find. It would be interesting to combine experimental designs with qualitative techniques of data collection, attempting to confirm the psychosocial effects of specific groupbased physical activity programs for this population, as well as to identify possible problems that may arise during the course of such programs. Thereby, we would obtain more vital and comprehensive knowledge to design and implement appropriate programs of physical activity for these patients. Another of the limitations found in this review is that most of the studies do not use a theoretical framework of reference. Of the 23 articles that make up this systematic review, only 5 studies used the theory of planned behavior, 2 applied the ecological model of health behavior, and only 1 study is based on self-determination theory to analyze the factors that influence adherence to physical activity in patients with colorectal cancer. However, as some authors indicate (Biddle et al., 2012), it is necessary to apply theoretical frameworks that guide the studies and allow us to understand the information accurately and in a structured way. Accordingly, it is striking that only one study applied self-determination theory with colorectal cancer patients, taking into account that this theory has proven to be one of the most relevant to study behavior in health contexts (Ng et al., 2012). Besides, most of the studies measure physical activity by means of questionnaires, except for one study that incorporated a more objective measure using accelerometry. New studies are necessary to analyze the levels of physical activity in patients with colorectal cancer objectively, in order to determine their relationships with different factors that may increase or decrease them. The increasingly advanced development of wearable devices for tracking physical activity could facilitate this task accordingly. Lastly, out of the 23 reviewed articles, 11 studies analyzed the factors associated with the performance of physical activity during the complementary treatment to surgery, another 9 were carried out after finishing the treatment or only a minority of patients was in treatment, and 3 studies did not specify the time of treatment. From our viewpoint, the differences between the factors that promote or hinder physical activity participation during and after the complementary treatment to surgery remain unclear. 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