Relationship between body mass index and stage at breast cancer diagnosis

 Corresponding author: Kingsley Odinaka Idoko Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0. Relationship between body mass index and stage at breast cancer diagnosis Kingsley Odinaka Idoko * and Kenneth Oluchukwu Ugwuanyi Department of Surgery, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria. World Journal of Advanced Research and Reviews, 2025, 27(01), 2401-2406 Publication history: Received on 09 June 2025; revised on 14 July 2025; accepted on 17 July 2025 Article DOI: https://doi.org/10.30574/wjarr.2025.27.1.2693 Abstract Background: The relationship between Body Mass Index (BMI) and risk of developing breast cancer is very well researched. However, there is a relative dearth of studies on the relationship between BMI and the stage of breast cancer at diagnosis. This study aims to explore this relationship. Aims/objectives: The aim of this study was to evaluate if there is any relationship between BMI and the stage of breast cancer at diagnosis among women attending the Breast Clinic of a tertiary health facility in Nigeria. Methods: This was a retrospective study (n=110) conducted at Nnamdi Azikiwe University Teaching Hospital, Anambra State. The BMI categories of participants and the clinicopathological stages of their tumours were obtained from the medical files of consenting patients who met the inclusion criteria. The data was analysed using the Statistical Programme for the Social Sciences (SPSS) Version 20.0. Logistic regression was used to draw association between stages of cancer at diagnosis and BMI categories. Results: The mean BMI(SD) was 28.09(6.35)kg/m2. There was a moderate, statistically significant positive correlation between being overweight/obese and having a late stage at diagnosis of breast cancer (OR=2.36, 95% C.I.: 1.06-5.27; P=0.03). After controlling for age, occupation and highest educational attainment, this association was slightly stronger (O.R=3.29, 95% C.I: 1.31-9.10). Conclusion: There is a need to place particular emphasis on very rigorous breast self-examination in women with high BMI as they are likely to present with more advanced tumours. Keywords: Breast cancer; Stage; BMI; Obesity; Overweight 1. Introduction Body Mass Index (BMI) is one of the many metrics used to assess if an individual is underweight, overweight, obese or morbidly obese. The United States National Institute for Health (NIH) has defined being overweight as having a BMI between 25-29.9 and obesity as a BMI of 30.0 or more (1). It is generally agreed that obesity is an independent risk factor for the development of breast cancer. This association is unequivocal in post-menopausal women (2-8), but more ambiguous in pre-menopausal women, with some studies suggesting a direct relationship (3,9,10) while some suggest an inverse relationship (11-14). The relationship between body mass/obesity and stage at breast cancer diagnosis for women of all age groups (postmenopausal or premenopausal) is even more blurred, firstly because of a relative paucity of such studies, secondly because of some ambiguity in the few studies already conducted and thirdly because the picture seems to be complicated by the method of detection of the breast cancer in the first instance (15). Howson et al noticed in their study World Journal of Advanced Research and Reviews, 2025, 27(01), 2401-2406 2402 that being overweight or obese was unassociated with tumor stage, tumor size or extent of axillary node disease at the time of diagnosis (16), similar to findings in some other studies (17,18). However, an overwhelming majority of studies find that obesity is positively related to more advanced disease at diagnosis (15,19-27). There is also some discrepancy as to what component(s) of the staging i.e tumor size or lymph node involvement (or both) has some correlation with obesity; one study (13) found obesity to relate only to lymph node involvement, but not tumour size at diagnosis. Other studies (12,21,27-29) report that tumour size, but not lymph node involvement have a correlation with obesity, while others (19,30,31) found obesity being linked to both large tumour size and lymph node involvement. It had long been thought that the significantly later presentation among black breast cancer patients in the United States compared to their white counterparts was occasioned by cultural and socioeconomic factors but one study suggests it could be due to a difference in the relative prevalence of severe obesity in both racial groups with black women having a noticeably higher incidence of severe obesity than white women and with severe obesity being associated with later stages at diagnosis (19). Some studies have also shown a relationship between patients with larger breasts and later stages at presentation, suggesting that the delayed presentation may be due to some difficulty in recognising the existence of the lump in the first place (20). Aim of study Because women with higher BMI may generally have larger and denser breasts, it may be more difficult to notice, by palpation or mammography, appearance of any new lumps, delaying presentation and thereby leading to more advanced diseases at presentation. Furthermore, obesity may impart a higher degree of invasiveness to breast cancers. The study was aimed at delineating the relationship between BMI categories and the stage of breast cancer at diagnosis among women in a healthcare centre in South-Eastern Nigeria. 2. Methodology This study was carried out in a government-owned tertiary health facility in Nigeria. Ethical clearance was obtained from the Nnamdi Azikiwe University Teaching Hospital Ethical Committee. It was a retrospective study using information from the medical files of 110 consecutive patients seen at the Breast Clinic of the facility from January 2022 to December 2023. The inclusion criteria were all consenting females above 25 years of age who had diagnoses of breast cancer and who were being managed at the Breast Clinic in the hospital. The participants were contacted using information in their medical notes before collection of data and their consent was gotten. Patients who were already cachectic at diagnosis or who did not give their consent (or could not be contacted) were excluded from the study. Patients’ weights and heights are some of the anthropometric measurements routinely taken during visits to the Breast Clinic. The body weights are obtained by trained clinic assistants using a weighing scale (OMRON HBF-510 W) and heights are obtained (to the nearest cm) using a rigid measuring tape. The BMI was calculated as: Body Weight(kg) ÷ height(m2) and the value was approximated to two decimal places. BMI used in this case was the BMI at the point of histological/clinical diagnosis and staging. A subject was regarded as having a normal weight if their BMI was between 18.5-24.9kg/m2, as being overweight if their BMI was between 25.0-29.9kg/m2 and as being obese if their BMI was equal to or greater than 30.0kg/m2. Tumours of Stages 0, 1A, 1B and 2A were classed as “early stage” while those of Stages 2B, 3A, 3B, 3C and 4 were classed as “late stage”. The Statistical Program for the Social Sciences (SPSS) version 20.0 was used for data analysis. 3. Results The modal age range of participants was 51-75 years, with those in this age range accounting for 45.5% of the total participants, followed closely by those in the age range 26-50 years who accounted for 42.7% of total participants. The mean participant age (SD) was 54.06(13.09) years. Just over half of the subjects had early stage tumours (58 participants, 52.7%) while the rest had late stage tumours. The mean BMI(SD) was 28.09(6.35)kg/m2. A significant majority (55.5%) of the participants were traders due to the socioeconomic characteristics of the region where the study was carried out. 37.3% of participants attained a tertiary level of education. The sociodemographic characteristics of the participants are highlighted in Table 1. World Journal of Advanced Research and Reviews, 2025, 27(01), 2401-2406 2403 There was a moderate, statistically significant positive correlation between being overweight/obese and having a late stage at diagnosis of breast cancer (OR=2.36, 95% C.I.: 1.065.27; P=0.03). After controlling for age, occupation and highest educational attainment, this relationship was even stronger (O.R=3.26, 95% C.I: 1.31-9.10). (Tables 2 and 3). 4. Discussion Our findings show that older women have a higher risk of breast cancer development, corroborating findings from prevalence studies on age-related risk (32,33). Generally, breast cancer incidence has been noted to be positively positively correlated with advanced ages with a peak at ages greater than 70 years (34, 35) . Liu et al. (36) in a doseresponse meta-analysis evaluating the relationship between obesity and breast cancer recorded a 2% increase in the risk of breast cancer for every 5 unit rise in the BMI in pre-menopausal women. Paradoxically, some studies suggest that a higher BMI may be protective of breast cancer in pre-menopausal women (37). The higher risk of breast cancer in obese post-menopausal women has been ascribed to the significantly higher activity of aromatase in this cohort, particularly in adipose tissue, where it converts androgens into estrogen (38). Since estrogen is mitogenic for mammary cells, the increase in estrogen levels may drive them to undertake repeated rounds of cell division, increasing breast cancer risk (37). Apart from the risk on the development of breast cancer, BMI levels have also been noted to affect disease outcome in women diagnosed with breast cancer. Obesity has been shown to correlate with larger primary tumour sizes and increased invasiveness, ultimately worsening the prognosis in this cohort of patients (39,40). Once again, these may be due to higher levels of estrogen from adipose tissue (41). A further layer of complexity may be due to the size of the predisease breasts. Because overweight and obese women generally have larger breasts, it may be more difficult for them and/or their partners to notice small breast lumps, leading to their presentation at later stages (42,43). 5. Conclusion Early diagnosis of breast cancer is important as it enables prompt initiation of care. This study establishes that overweight/obese patients are at risk of presenting at more advanced stages of breast cancer compared to their normal weight counterparts. Policies that promote weight loss through lifestyle modification may reduce the overall risk of breast cancer development in all women. Routine breast selfexamination remains a simple, cheap and invaluable method of screening for lumps and other changes in the breasts. There may be a need to educate women with higher BMI levels (and larger breasts) on the need to be extra-rigorous in their breast self-examination to enable earlier detection and possibly improve prognosis. More studies are very much needed to strengthen or refute this relationship delineated here. Importantly, maybe new studies can focus on investigating any relationships between actual size/weight of pre-disease or unaffected breasts and stage at breast cancer diagnosis; such studies may more accurately delineate he relationship between breast size and stage at diagnosis. Table 1 Characteristics of study subjects Characteristics Frequency Percentage Age(years) 26-50 47 42.7 51-75 50 45.5 >=76 13 11.8 Mean 54.06±13.09 Occupation Dependent 17 15.5 Trader 61 55.5 Artisan 5 4.5 Civil servant 19 17.3 World Journal of Advanced Research and Reviews, 2025, 27(01), 2401-2406 2404 Retired 4 3.6 Student 4 3.6 Education No formal education 5 4.5 Primary 33 30 Secondary 31 28.2 Tertiary 41 37.3 Stage Early 58 52.7 Late 52 47.3 BMI (kg/m2) Underweight 0 0.00 Healthy weight 41 37.30 Overweight 22 20.00 Obese 47 42.70 Mean 28.09±6.35 Table 2 Relationship between body mass index (BMI) and stage at breast cancer diagnosis BMI Stage Total n (%) X2 p-value Early n (%) Late n (%) Overweight/Obese 31 (44.9) 38 (55.1) 69 (62.7) 4.518 0.034 Normal weight 27 (65.9) 14 (34.1) 41 (37.3) There is a positive significant relationship between high body mass index (overweight/obesity) and later stage at breast cancer diagnosis.; Note: pvalue less than 0.05 was regarded as statistically significant. Table 3 Odd Ratio and 95% CI for being diagnosed with late stage in overweight/obese women compared with normal weight women BMI B S.E. Wald Df Sig. Unadjusted OR (95 % CI) Adjusted OR (95 % CI) Overweight/Obese 0.86 0.409 4.432 10 0.035 2.364 (1.06-5.27) 3.29(1.31-9.10) Normal weight R r R Adjusted odd ratio = adjusted for age, occupation, education level. Women who were overweight/obese were more likely to be diagnosed with late stage of cancer (OR=2.36, 95% C.I.: 1.06-5.27; P=0.03) than women of normal weight. Additionally, after controlling for age, occupation and educational level, overweight/obese women had significantly higher odds of late stage at diagnosis when compared with women of normal weight. Compliance with ethical standards Disclosure of conflict of interest No conflict of interest to be disclosed. Statement of ethical approval This study was conducted in compliance with the relevant ethical standards in the Declaration of Helsinki. Ethical clearance was obtained from the Nnamdi Azikiwe University Teaching Hospital Ethical Committee. World Journal of Advanced Research and Reviews, 2025, 27(01), 2401-2406 2405 Statement of informed consent Informed consent was obtained from all individual participants included in the study. References [1] National Institute of Health’s website: https://www.nhlbi.nih.gov/health/overweight-andobesity/symptoms accessed on 27/04/24 [2] Cleary MP, Maihle NJ. The role of body mass index in the relative risk of developing premenopausal versus postmenopausal breast cancer. Proceedings of the Society for Experimental Biology and Medicine. 1997; 216: 28–43. [3] Huang Z, Hankinson SE, Colditz GA, Stampfer M.J, Hunter DJ, Manson JE et al. Dual effects of weight and weight gain on breast cancer risk. Journal of the American Medical Association. 1997; 278: 1407–11. [4] Ursin G, Longnecker MP, Haik RW, Greenland S. A meta-analysis of body mass index and risk of premenopausal breast cancer. Epidemiology 1995; 6: 137–41. [5] Ballard-Barbash R. Anthropometry and breast cancer. Body size—a moving target. Cancer. 1994; 74: 1090–100. [6] Hunter DJ, Willett WC. Diet, body size, and breast cancer. Epidemiologic Reviews. 1993; 15: 110–32. [7] Stoll BA. Obesity and breast cancer. International Journal of Obesity and Related Metabolic Disorders. 1996; 20: 389–92. [8] Yong LC, Brown CC, Schatzkin A, Schairer C. A prospective study of relative weight and risk of breast cancer: the Breast Cancer Detection Demonstration Project follow-up study, 1979 to 1987–1989. American Journal of Epidemiology. 1996; 143: 985–95. [9] Vatten LJ, Kvinnsland S. Prospective study of height, body mass index and risk of breast cancer. Acta Oncological. 1992; 31: 195–200. [10] Katoh A, Watzlaf VJ, D’Amico F. An examination of obesity and breast cancer survival in post-menopausal women. British Journal of Cancer. 1994; 70: 928–933. [11] Peacock SL, White E, Daling JR, Voigt LF, Malone KE. Relation between obesity and breast cancer in young women. American Journal of Epidemiology. 1999; 149: 339–346. [12] Senie RT, Rosen PP, Rhodes P, Lesser ML, Kinne DW. Obesity at diagnosis of breast carcinoma influences duration of disease-free survival. Annals of Internal Medicine. 1992; 116: 26–32. [13] Schapira DV, Kumar NB, Lyman GH, Cox CE. Obesity and body fat distribution and breast cancer prognosis. Cancer. 1991; 67: 523–528. [14] Willett WC, Browne ML, Bain C, Lipnick RJ, Stampfer MJ, Rosner B, et al. Relative weight and risk of breast cancer among premenopausal women. American Journal of Epidemiology. 1985; 122: 731–740. [15] Cui Y, Whiteman MK, Flaws J.A, Langenberg P, Tkaczuk KH, Bush, TL. Body mass and stage of breast cancer at diagnosis. International Journal of Cancer. 2002; 98: 279–283. [16] Howson CP, Kinne D, Wynder EL. Body weight, serum cholesterol, and stage of primary breast cancer. Cancer. 1986; 58: 2372–81. [17] De Waard F., Cornelis J. P., Aoki, K., Yoshida, M. Breast cancer incidence according to weight and height in two cities of the Netherlands and in Aichi Prefecture, Japan. Cancer. 1977; 40: 1269–1275. [18] De Waard, F., Body size, body mass and cancer of the breast. In: C. Ip, D. F. Birt, A. E. Rogers and C. Mettlin (eds.), Dietary fat and cancer, New York, A.R. Liss, 1986, p. 33 [19] Jones BA, Kasi SV, Curnen MG, Owens PH, Dubrow R. Severe obesity as an explanatory factor for the black/white difference in stage at diagnosis of breast cancer. American Journal of Epidemiology. 1997; 146: 394–404. [20] Hall HI, Coates RJ, Uhler RJ, Brinton LA, Gammon MD, Brogan D et al. Stage of breast cancer in relation to body mass index and bra cup size. International Journal of Cancer. 1999; 82: 23–7. [21] Weiss SE, Tartter PI, Ahmed S, et al. Ethnic differences in risk and prognostic factors for breast cancer. Cancer. 1995; 76: 268–74. World Journal of Advanced Research and Reviews, 2025, 27(01), 2401-2406 2406 [22] Ingram D, Nottage E, Ng S, Sparrow L, Roberts A, Willcox D. Obesity and breast disease. The role of the female sex hormones. Cancer. 1989; 64: 1049–53. [23] Reeves MJ, Newcomb PA, Remington PL, Marcus PM, MacKenzie W.R. Body mass and breast cancer. Relationship between method of detection and stage of disease. Cancer. 1996; 77: 301–7. [24] Zumoff B, Dasgupta I. Relationship between body weight and the incidence of positive axillary nodes at mastectomy for breast cancer. Journal of Surgical Oncology. 1983; 22: 217–20. [25] Den Tonkelaar I, De Waard F, Seidell JC, Fracheboud J. Obesity and subcutaneous fat patterning in relation to survival of postmenopausal breast cancer patients participating in the DOM-project. Breast Cancer Research and Treatment. 1995; 34: 129–37. [26] Greenberg ER, Vessey MP, McPherson K, Doll R, Yeats D. Body size and survival in premenopausal breast cancer. British Journal of Cancer. 1985; 51: 691–7. [27] Bastarrachea J, Hortobagyi GN, Smith TL, Kau SWC, Buzdar AU. Obesity as an adverse prognostic factor for patients receiving adjuvant chemotherapy for breast cancer. Annals of Internal Medicine. 1994; 120: 18–25. [28] London SJ, Colditz GA, Stampfer MJ, Willet WC, Rosner B, Speizer FE. Prospective study of relative weight, height, and risk of breast cancer. Journal of the American Medical Association. 1989; 262: 2853–8. [29] Hoe AL, Mullee MA, Royle GT, Guyer PB, Taylor I. Breast size and prognosis in early breast cancer. Annals of the Royal College of Surgeons of England. 1993; 75: 18–22. [30] Daniell HW. Increased lymph node metastases at mastectomy for breast cancer associated with host obesity, cigarette smoking, age, and large tumor size. Cancer. 1988; 62: 429–35. [31] Verreault R, Brisson J, Deschenes L, Naud F. Body weight and prognostic indicators in breast cancer. Modifying effect of estrogen receptors. American Journal of Epidemiology. 1989; 129: 260–8. [32] DeSantis C, Siegel R, Bandi P, Jemal A. Breast cancer statistics. CA: a Cancer Journal for Clinicians. 2011; 61: 409418 [33] Siegel R, Ma J, Zou Z, Jemal A. Cancer statistics. CA: a Cancer Journal for Clinicians. 2014; 64: 9–29. [34] Yancik R. Cancer burden in the aged: An epidemiologic and demographic overview. Cancer. 1997;80:1273–1283. [35] International Cancer Screening Network. [(accessed on 18 June 2024)]; Available online: http://appliedresearch.cancer.gov/icsn/breast/screening.html#f6) [36] Liu K, Zhang W, Dai Z, Wang M, Tian T, Liu X, et al. Association between body mass index and breast cancer risk: Evidence based on a dose–response meta-analysis. Cancer management and research. 2018;10:143. [37] Dehesh T, Fadaghi S, Seyedi M, Abolhadi E, Ilaghi M, Shams P et al. The relation between obesity and breast cancer risk in women by considering menstruation status and geographical variations: a systematic review and meta-analysis. BMC Women’s Health. 2023; 23: 392. [38] Geczik AM, Falk RT, Xu X, Ansong D, Yarney J, Wiafe-Addai B etc al. Measured body size and serum estrogen metabolism in postmenopausal women: the Ghana Breast Health Study. Breast Cancer Research: BCR. 2022; 24:9. [39] Ligibel J. Obesity and breast cancer. Oncology. 2011; 25:994. [40] Neuhouser ML, Aragaki AK, Prentice RL, Manson JE, Chlebowski R, Carty CL et al. Overweight, Obesity, and Postmenopausal Invasive Breast Cancer Risk: A Secondary Analysis of the Women's Health Initiative Randomized Clinical Trials. JAMA Oncology. 2015; 1:611-21. [41] Zhao S, Chlebowski RT, Anderson GL, Kuller LH, Manson JE, Gass M et al. Sex hormone associations with breast cancer risk and the mediation of randomized trial postmenopausal hormone therapy effects. Breast Cancer Research: BCR. 2014; 16: 30. [42] Foroozani E, Ghiasvand R, Mohammadianpanah M, Afrashteh S, Bastam D, Kashefi F et al. Determinants of delay in diagnosis and end stage at presentation among breast cancer patients in Iran: a multi-center study. Scientific Reports. 2020; 10:21477. [43] Arndt V, Stürmer T, Stegmaier C, Ziegler H, Dhom G, Brenner H. Patient delay and stage of diagnosis among breast cancer patients in Germany -- a population based study. British Journal of Cancer. 2002; 86:1034-40.