Liver metastases of intrahepatic Cholangiocarcinoma: implications for an updated staging system

2311 Hepatology, Vol. 73, No. 6, 2021 Liver Metastases of Intrahepatic Cholangiocarcinoma: Implications for an Updated Staging System Angela Lamarca ,1 Alvaro SantosLaso,2 Kirsten Utpatel,3 Adelaida La Casta,2 Simone Stock,3 Alejandro Forner ,4,5 Jorge Adeva ,6 Trine Folseraas,7 Luca Fabris,8 Rocio I.R. Macias ,5,9 Marcin Krawczyk,10,11 Marek Krawczyk,12 Vincenzo Cardinale,13 Chiara Braconi,14 Domenico Alvaro,13 Matthias Evert,3 Jesus M. Banales,2,5,15 and Juan W. Valle1, for the Group: on behalf of the European Network for the Study of Cholangiocarcinoma (ENSCCA) BaCKgRoUND aND aIMS: Intrahepatic cholangiocarcinoma (iCCA) with liver metastases is perceived to have a poor prognosis, but the American Joint Committee on Cancer (AJCC) classifies them as early stage in the absence of lymph nodes or extrahepatic spread. appRoaCH aND ReSUltS: Patients with iCCA from the European Network for the Study of Cholangiocarcinoma (ENSCCA) and Surveillance, Epidemiology, and End Results (SEER) registries with survival/staging (AJCC v.7) data were eligible. Modified staging was used (mAJCC v.7): group A: stages IIII (excluding T2bN0); group B: stage IVa (excluding T2bN1M0); group C: liver metastases (T2bN0/1); and group D: stage IVb (extrahepatic metastases). Survival analysis (KaplanMeier and Cox regression) was performed in an ENSCCA training cohort (TC) and findings internally (ENSCCA iVC) and externally (SEER) validated. The aim was to assess whether liver metastases (group C) had a shorter survival compared to other early stages (group A) to propose a modified version of AJCC v.8 (mAJCC v.8). A total of 574 and 4,171 patients from the ENSCCA and SEER registries were included. Following the new classification, 19.86% and 17.31% of patients from the ENSCCA and SEER registries were reclassified into group C, respectively. In the ENSCCA TC, multivariable Cox regression was adjusted for obesity (p = 0.026) and performance status (P < 0.001); patients in group C (HR, 2.53; 95% CI, 1.185.42; P = 0.017) had a higher risk of death (vs. group A). Findings were validated in the ENSCCA iVC (HR, 2.93; 95% CI, 2.044.19; P < 0.001) and in the SEER registry (HR, 1.88; 95% CI, 1.682.09; P < 0.001). CoNClUSIoNS: iCCA with liver metastases has a worse outcome than other early stages of iCCA. Given that AJCC v.8 does not take this into consideration, a modification of AJCC v.8 (mAJCC v.8), including “liver metastases: multiple liver lesions, with or without vascular invasion” as an “M1a stage,” is suggested. (Hepatology 2021;73:2311-2325). Biliary tract cancer (BTC) includes gallbladder cancer (GBC), cholangiocarcinoma (CCA), and ampullary tumors (AMPs). CCAs are Abbreviations: AJCC, American Joint Committee on Cancer; CCA, cholangiocarcinoma; ECOGPS, Eastern Cooperative Oncology Group performance status; ENSCCA, European Network for the Study of Cholangiocarcinoma; iCCA, intrahepatic cholangiocarcinoma; IQR, interquartile range; M, metastasis; mAJCC, modified American Joint Committee on Cancer; mAJCC v.7, modified version of the AJCC v.7 staging criteria; mAJCC v.8, modified AJCC v.8; N, node; OS, overall survival; SEER, Surveillance, Epidemiology, and End Results; T, tumor. Received May 5, 2020; accepted September 20, 2020. Additional Supporting Information may be found at onlinelibrary.wiley.com/doi/10.1002/hep.31598/suppinfo. © 2020 The Authors. Hepatology published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases. This is an open access article under the terms of the Creative Commons AttributionNonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. View this article online at wileyonlinelibrary.com. DOI 10.1002/hep.31598 Potential conflict of interest: Dr. Lamarca advises for and received grants from Roche and Ipsen. She is on the speakers’ bureau for and received grants from AAA and Pfizer. She advises for Eisai and Nutricia. She is on the speakers’ bureau for Merck and Incyte. She received grants from Bayer, Sirtex, Novartis, Mylan, and Delcath. Dr. Forner consults for, is on the speakers’ bureau for, and received grants from Bayer. He consults for Guerbet and AstraZeneca. He is on the speakers’ bureau for MSD and Gilead. Dr. Braconi is on the speakers’ bureau for Bayer, Eli Lilly, Pfizer, Merck, and Serono. Dr. Valle advises for and is on the speakers’ bureau for Ipsen and Novartis. He is on the speakers’ bureau for and received grants from Nucana. He advises for Agios, AstraZeneca, Delcath, Keocyt, Genoscience, Incyte, Merck, Mundipharma, PCT Biotech, Pfizer, and Qed. He is on the speakers’ bureau for AAA. He received grants from Celgene. Dr. LaCasta received grants from Roche, Amgen and PierreFabré outside the scope of this work. Dr. Banales reports grants from INCYTE, personal fees for lecturer from BAYER and INTERCEPT, and consulting for QED Therapeutics, Albireo Pharma and OWL METABOLOMICS, outside the submitted work. Hepatology, June 2021LAMARCA ET AL. 2312 subdivided according to location into intrahepatic (iCCA) and extrahepatic CCA (eCCA). iCCA represents the secondmost common primary liver cancer after HCC.(1) iCCA has received substantial attention in recent years given the progressive worldwide increase in incidence. Prognosis is poor because of the fact that BTCs usually present in advanced stages attributable to their asymptomatic nature in early stages.(2,3) Thus, there is an urgent need to develop better diagnostic and therapeutic strategies for patients affected by these cancers.(46) For many years, iCCAs were joined together with other BTCs, and clinical trials have traditionally recruited all subgroups of BTC. In fact, current standardofcare adjuvant(7,8) and palliative(912) chemotherapy for BTC does not distinguish between BTC subtypes. In contrast, there is increasing evidence suggesting that iCCA, eCCA, GBC, and AMPs have different etiological, clinical, genomic, and molecular characteristics.(5) Among all BTCs, iCCAs are gaining lots of attention for a variety of reasons. First, patients diagnosed with iCCA rarely present with biliary obstruction and jaundice, which may lead to an increased percentage of patients diagnosed with advanced disease, when no curative options are available.(6) In addition, chronic liver diseases (NAFLD, viral hepatitis [B or C], and cirrhosis) are wellknown risk factors for both iCCA and HCC, making radiological differentiation of iCCA from HCC in patients with underlying liver disease challenging. However, most iCCAs develop in the absence of underlying liver disease, thus making screening programs challenging.(6) Second, a proportion of iCCAs may develop multiple liver lesions (“liver metastases”), with no evidence of extrahepatic disease; therefore, liverdirected therapies(13,14) and external beam radiotherapy(15) could be used as potential treatment options. Third, there is evidence suggesting that patients diagnosed with iCCA have a better prognosis compared to other advanced BTCs.(16) Finally, there is strong evidence indicating that genomic and molecular aberrations in iCCA differ from other BTCs,(17) mainly represented by increased presence of fibroblast growth factor receptor 2 fusion rearrangements and isocitrate dehydrogenase1 and - 2 mutations.(18,19) Identification of these molecular alterations has direct implications for access to targeted therapies and precision medicine strategies, whose success is currently almost limited to iCCA among the BTCs.(20) aRtICle INFoRMatIoN: From the 1 Medical Oncology/Institute of Cancer Sciences, The Christie NHS Foundation Trust/University of Manchester, Manchester, United Kingdom; 2 Department of Liver and Gastrointestinal Diseases, Biodonostia Health Research Institute, Donostia University Hospital, University of the Basque Country (UPV/EHU), San Sebastian, Spain; 3 Institute of Pathology, University of Regensburg, Regensburg, Germany; 4 BCLC group, Liver Unit, Hospital Clínic Barcelona, Barcelona, Spain; 5 National Institute for the Study of Liver and Gastrointestinal Diseases (CIBERehd), The National Institute of Health Carlos III, Madrid, Spain; 6 Depart ment of Medical Oncology, Hospital Universitario 12 de Octubre, Madrid, Spain; 7Section of Gastroenterology and the Norwegian PSC Research Center, Department of Transplantation Medicine, Oslo University Hospital, Oslo, Norway; 8 Department of Molecular Medicine, University of Padua, Padua, Italy; 9 Experimental Hepatology and Drug Targeting (HEVEPHARM) group, University of Salamanca, IBSAL, Salamanca, Spain; 10 Department of Medicine II, Saarland University Medical Centre, Saarland University, Homburg, Germany; 11 Laboratory of Metabolic Liver Diseases, Centre for Preclinical Research, Department of General, Transplant and Liver Surgery, Medical University of Warsaw, Warsaw, Poland; 12 Department of General, Transplant and Liver Surgery, Medical University of Warsaw, Warsaw, Poland; 13 Gastroenterology, Sapienza University of Rome, Rome, Italy; 14 Medical Oncolog y, The University of Glasgow, Glasgow, United Kingdom; 15 IKERBASQUE, Basque Foundation for Science, Bilbao, Spain. aDDReSS CoRReSpoNDeNCe aND RepRINt ReQUeStS to: Juan W. Valle, M.B., Ch.B., M.Sc., F.R.C.P. Division of Cancer Sciences, University of Manchester; Department of Medical Oncology The Christie NHS Foundation Trust Wilmslow Road Manchester M20 4BX, United Kingdom Email: [email protected] Tel.: +44 161 446 3000 or Angela Lamarca, M.D., M.Sc., Ph.D. Department of Medical Oncology The Christie NHS Foundation Trust Division of Cancer Sciences, University of Manchester Wilmslow Road Manchester M20 4BX, United Kingdom Email: [email protected] Tel.: +44 161 446 3000 Hepatology, Vol. 73, No. 6, 2021 LAMARCA ET AL. 2313 The most commonly used staging classification in oncology is the one developed by the American Joint Committee on Cancer (AJCC).(21) Staging criteria for CCA were not introduced until the 2nd Edition (published in 1983 and made effective in 1984).(22) In addition, iCCA was staged together with other primary liver tumors, such as HCC, and it was not until the 7th Edition (published in 2009 and effective between 2010 and 2017; AJCC v.7; Table 1)(23) that a specific staging system for iCCA was provided. The latest update was published in 2016 and made effective in 2018 (8th Edition).(23) Several changes were applied in this latest version, involving, in particular, the tumor (T) staging (AJCC v.8; Table 1). The T1 category was subdivided according to tumor size, whereas the T3 and T4 definitions were slightly modified and assigned to stage III disease (if M0). Moreover, the previously defined T2a (solitary lesion with vascular invasion) and T2b (multiple tumors; socalled liver metastases for the purpose of this study) categories were merged. As stated above, a significant proportion of patients (up to 48%) with iCCA may develop multiple liver lesions in the absence of other extrahepatic metastases.(16) This liveronly pattern is not unique to iCCA, but can also be observed in other primary liver cancers, such as HCC. In HCC, the scenario of multiple liver lesions may represent multiple primary tumors (multifocal disease) arising in the background of cirrhosis. However, this phenomenon is still elusive in iCCA, especially when detected in the absence of a preexisting liver disease such as cirrhosis, primary sclerosing cholangitis, or exposure to specific chemicals.(2426) In the majority of patients diagnosed with iCCA, presence of multiple liver lesions usually reflects hematogenous intrahepatic dissemination (liver metastases) from a primary predominant tumoral liver lesion and is clinically expected to feature worse prognosis, more similar to metastatic disease than to earlier stages. In fact, these patients are usually managed with palliative strategies, similar to conditions where other distant metastases have been identified.(27) In contrast, current staging systems, such as the AJCC, do not take account for this issue and, in the absence of other sites of distant metastases, the AJCC still classifies liver metastases in iCCA as early stage in the absence of lymph node or extrahepatic spread(23,28) (Table 1). The European Network for the Study of Cholangiocarcinoma (ENSCCA) represents an open, multidisciplinary group of clinical, translational, and basic researchers aiming to improve the knowledge on CCA and promote translational activities; as part of the ENSCCA initiatives, a multicenter panEuropean clinical registry of patients with CCA has been in development since 2016, including both retrospective (from 2010) and prospective data.(4) This study aimed to describe the outcomes of patients with iCCA complicated by liver metastases and compare them to other earlier stages, in order to ascertain whether current staging accurately reflects natural behavior and aggressiveness, or whether any changes to the current staging system should be considered. Patients and Methods StUDy DeSIgN A modified version of the AJCC v.7 staging criteria (mAJCC v.7; Table 1), where patients diagnosed with liver metastases (T2b) were classified as a separate group (group C) regardless of node (N) status (any N) and in the absence of other sites of distant metastases (M0), was generated. Groups were defined as follows: group A (stages IIII [excluding T2bN0M0]); group B (stage IVa [excluding T2bN1M0]); group C (liver metastases: multiple liver lesions, with or without vascular invasion [T2b, any N, M0], group of interest); and group D (stage IVb [M1 extrahepatic disease]). The primary objective of this study was to apply both the AJCC v.7 and mAJCC v.7 classification to assess whether patients with liver metastases (regardless of lymph node status; group C) had a different prognosis compared to other earlystage disease (stages IIII; group A), using overall survival (OS) as the primary endpoint (defined as the time from first diagnosis to death/last visit). Given that the AJCC v.8 classification does not differentiate between number of liver lesions (T2 stage includes solitary lesions with vascular invasion and multiple liver lesions within the same group), the analysis was performed using the AJCC v.7 (which provides the distinction between T2a and T2b subgroups). The secondary objective was to create a modified AJCC v.8 (mAJCC v.8) that could be used for the development of future AJCC versions. Hepatology, June 2021LAMARCA ET AL. 2314 taBle 1.Current Staging of CCa (aJCC 7th and 8th editions and Corresponding Modified Versions) iCCA AJCC v.7 mAJCC v.7 Modified version used to assess impact of liver metastases AJCC v.8 mAJCC v.8 Proposed modified version of the current AJCC v.8 Primary tumor (T) TX Primary tumor cannot be assessed. Primary tumor cannot be assessed. Primary tumor cannot be assessed. Primary tumor cannot be assessed. T0 No evidence of primary tumor No evidence of primary tumor No evidence of primary tumor No evidence of primary tumor Tis Carcinoma in situ (intraductal tumor) Carcinoma in situ (intraductal tumor) Carcinoma in situ (intraductal tumor) Carcinoma in situ (intraductal tumor) T1 Solitary tumor without vascular invasion Solitary tumor without vascular invasion — — T1a — — Solitary tumor ≤5 cm without vascular invasion Solitary tumor ≤5 cm without vascular invasion T1b — — Solitary tumor >5 cm without vascular invasion Solitary tumor >5 cm without vascular invasion T2 — — Solitary tumor with intrahepatic vascular invasion or multiple tumors with or without vascular invasion Solitary tumor with intrahepatic vascular invasion T2a Solitary tumor with vascular invasion Solitary tumor with vascular invasion — — T2b Multiple tumors, with or without vascular invasion Multiple tumors, with or without vascular invasion — — T3 Tumor perforating the visceral peritoneum or involving local hepatic structures by direct invasion Tumor perforating the visceral peritoneum or involving local hepatic structures by direct invasion Tumor perforating the visceral peritoneum Solitary tumor perforating the visceral peritoneum T4 Tumor with periductal invasion Tumor with periductal invasion Tumor involving local extrahepatic structures by direct invasion Solitary tumor involving local extrahepatic structures by direct invasion Regional lymph nodes (N) NX Regional lymph nodes cannot be assessed. Regional lymph nodes cannot be assessed. Regional lymph nodes cannot be assessed. Regional lymph nodes cannot be assessed. N0 No regional lymph node metastasis No regional lymph node metastasis No regional lymph node metastasis No regional lymph node metastasis N1 Regional lymph node metastasis present Regional lymph node metastasis present Regional lymph node metastasis present Regional lymph node metastasis present Distant metastasis (M) M0 No distant metastasis No distant metastasis No distant metastasis No distant metastasis M1 M1a: liver metastases: multiple liver lesions, with or without vascular invasion Distant metastasis present Distant metastasis present Distant metastasis present M1b: Distant (extrahepatic) metastasis present Prognostic stage groups 0 Tis, N0, M0 Tis, N0, M0 Tis, N0, M0 Tis, N0, M0 I T1, N0, M0 T1, N0, M0 (group A) — T1, N0, M0 Ia — — T1a, N0, M0 T1a, N0, M0 Ib — — T1b, N0, M0 T1b, N0, M0 II T2a/b, N0, M0 T2a, N0, M0 (group A) T2, N0, M0 T2, N0, M0 Hepatology, Vol. 73, No. 6, 2021 LAMARCA ET AL. 2315 In order to generate the abovementioned staging groups, individual patient data on the T, N, and metastasis (M) stage was individually reviewed and staging groups defined for individual patients. As a quality control, patients with mismatching information were reviewed (if required) or excluded (if unable to satisfactorily reply to issued queries). DeFINItIoN oF a MoDIFIeD StagINg SySteM: tRaININg aND INteRNal ValIDatIoN CoHoRtS Data from patients included in the ENSCCA registry up to February 2019 were retrospectively analyzed. In order for data to be included in the registry, individual sites involved had obtained appropriate ethical approval; ethical guidelines of the 1975 Declaration of Helsinki were met. Eligible patients were those with a diagnosis of iCCA with available data of survival and staging (according to AJCC v.7). Patients diagnosed with mixed HCCiCCA or with different subtypes of CCA were excluded. Two cohorts of patients were analyzed: (1) the training cohort, including consecutive patients in the ENSCCA registry from The Christie NHS Foundation Trust, who had been diagnosed between 2013 and 2017; (2) the internal validation cohort, including consecutive patients in the ENSCCA registry from The Christie NHS Foundation Trust, who had been diagnosed between 2017 and 2018, along with all patients included in the ENSCCA registry by other contributing centers (20132018). The aim was to use the training cohort for building a modified staging system and for these results to be validated in the internal validation cohort. By doing so, lessons learned from the training cohort could be used to improve the modified staging system before its application in the internal validation cohort, should this be required. All eligible patients included in this study were staged as per AJCC v.7 and mAJCC v.7 classification. The following assumptions were made at time of data interpretation: if metastatic sites were not reported, M stage was assumed to be M0; when presence/absence of lymph node metastases were unknown (Nx), these were assumed to be N0 disease; if two separate T or N stages were reported, the highest stage was used for analysis purposes. Patients with M0 disease with reported T2 tumors were excluded from the analysis if no further specification regarding T2a/T2b was provided. Statistical analysis The last update of clinical data was in February 2019. Patients who were alive at the time of the last followup were censored. Survival analysis was first performed in the training cohort, and then findings were validated in the internal validation cohort. Chisquare, Fisher’s exacttest, and t test were used whenever appropriate. The KaplanMeier method was used to estimate median OS. Additional survival analyses with univariate Cox regression and a logrank test were also performed. Stepwise Cox regression, including all baseline characteristics collected as part of the ENSCCA registry (including staging), was used for identification of variables of interest to be included in the multivariable Cox regression model (P value cutoff, 0.05). In order to adjust the multivariable Cox regression model to potential confounding factors impacting on patients’ outcome for which relying on statistical significance in the stepwise Cox regression model alone would not be fully appropriate, iCCA AJCC v.7 mAJCC v.7 Modified version used to assess impact of liver metastases AJCC v.8 mAJCC v.8 Proposed modified version of the current AJCC v.8 III T3, N0, M0 T3, N0, M0 (group A) — — IIIa — — T3, N0, M0 T3, N0, M0 IIIb — — T4, Any N, M0 or any T, N1, M0 T4, N0, M0 or any T, N1, M0 IV — Any T, any N, M1 — IVa T4, N0, M0 or any T, N1, M0 T4, N0, M0 or any T (except T2b), N1, M0 (group B) — Any T, any N, M1a — — T2b, any N, M0 (group C) — — IVb Any T, any N, M1 Any T, any N, M1 (group D) — Any T, any N, M1b taBle 1.Continued Hepatology, June 2021LAMARCA ET AL. 2316 a few variables with a welldefined prognostic impact were preselected to be included in the multivariable Cox regression model regardless of the stepwise Cox regression findings. These factors included: stage and performance status, in view of previous evidence suggesting their impact on OS in this disease group.(16) Twosided P values of <0.05 were considered statistically significant. Stata software (version 12.0; StataCorp LP, College Station, TX) was used for the statistical analysis. Sensitivity analysis In order to confirm that our originally proposed definition of group C was adequate, a sensitivity analysis was performed. Given that the impact of lymph node positivity (N1) in the presence of liver metastases (T2b) is uncertain, a sensitivity analysis in the whole ENSCCA series by limiting group C to patients with N0 disease only (patients with N1 disease would be classified as group B) was completed. In the sensitivity analysis, group B was defined as “stage IVa, including T2b, N1, M0”) and group C as “T2b, N0, M0” (instead of “T2b, any N, M0” as defined for the rest of the analysis in this article). A decision was made to keep patients with N1 in group B instead of removing them from the analysis to explore whether prognosis was driven by liver metastases (T2b) on their own and independent from the presence of N1 disease. eXteRNal ValIDatIoN: SURVeIllaNCe, epIDeMIology, aND eND ReSUltS RegIStRy Data extracted from the Surveillance, Epidemiology, and End Results (SEER) registry were used for external validation.(29) Cases reported from 1975 through 2016 with available data on survival and stage (as per AJCC v.7) were deemed eligible. The staging assumptions used for the ENSCCA cohort were applied for the SEER registry. External validation with SEER data was aimed at confirming whether patients with liver metastases (regardless of lymph node status; group C) had indeed a different outcome compared to other “earlystage” disease (stages IIII; group A). Survival analysis with SEER data was performed using Cox regression analysis (multivariable analysis performed with ENSCCA data was planned to be reproduced, if variables of interest were available in the SEER dataset; otherwise, only a univariate analysis would be conducted). DeFINItIoN oF tHe pRopoSeD UpDateD aJCC ClaSSIFICatIoN Based on the information derived from mAJCC v.7 and the outcome of the current staging group, changes to the current AJCC v.8 in the form of an mAJCC v.8 were proposed, and outcomes of each specifically defined group were assessed in the joined ENSCCA and SEER cohort. Survival analysis was performed according to the previously indicated methodology. Results patIeNt CHaRaCteRIStICS: eNSCCa RegIStRy Of the 1,820 patients included in the ENSCCA registry, 810 had been diagnosed with iCCA and were assessed for eligibility. A total of 574 patients were eligible (141 within the training cohort [24.56%] and 433 in the internal validation cohort [75.44%]). Figure 1A summarizes patient flow for the ENSCCA cohort. Patient baseline characteristics, including treatment, for both the training and internal validation cohorts, are summarized in Table 2. Median followup time was 11.01 months (range, 0.00183.12; interquartile range [IQR], 4.0323.89) for the whole cohort; 8.99 (range, 0.0057.96; IQR, 3.4818.01) for the training cohort; and 11.39 (range, 0.00183.12; IQR, 4.3125.93) for the internal validation cohort (P=0.0017). For the whole cohort, median age at diagnosis was 66.16 years (range, 2692); the majority of patients were Eastern Cooperative Oncology Group performance status (ECOGPS) 0 (41.99%) or 1 (35.89%). Obesity and diabetes were present in 20.21% and 20.21% of patients, respectively. With respect to treatments, 47.21% of patients underwent previous surgical resection (5.67% and 60.74% in the training and internal validation cohorts, respectively; P < 0.001), whereas palliative chemotherapy was offered to 39.37% of patients (60.28% and 32.56% in the training and internal validation cohorts, respectively; P<0.001). StagINg oF iCCa: eNSCCa RegIStRy Staging groups in the ENSCCA registry, according to the AJCC v.7, mAJCC v.7, and mAJCC v.7 adjusted for sensitivity analysis are shown in Table 3. Hepatology, Vol. 73, No. 6, 2021 LAMARCA ET AL. 2317 When the whole population was staged based on the AJCC v.7 classification, 46.52%, 22.3%, and 31.18% of patients were stages IIII, IVa, and IVb disease, respectively. When applying the mAJCC v.7 classification, a total of 114 of the 395 (28.9%) patients previously staged as IIVa were reclassified into group C (75 N0; 39 N1), with 33.45%, 15.51%, 19.86%, and 31.18% of patients staged within groups A, B, C, and D, respectively. SURVIVal aNalySIS: eNSCCa RegIStRy Estimated median OS was 9.98 (95% CI, 6.9611.99; 135 events; 95.74% of patients), 18.52 (95% CI, 15.4422.07; 280 events; 64.67% of patients), and 15.01 months (95% CI, 12.6416.95; 415 events; 75.30% of patients) for the training, internal validation, and whole ENSCCA cohorts, respectively. In the training cohort, univariate survival analysis confirmed that both staging systems (AJCCv.7 and mAJCC v.7) had an impact on OS (Supporting Information S1A), with patients with distant metastases (stage IVb) demonstrating shorter OS. Similar findings were obtained in the univariate analysis using the internal validation cohort (Supporting Information S1B). Stepwise multivariable Cox regression analysis performed in the training cohort (Supporting Information S2) identified stage (HR, 1.37; 95% CI, 1.101.69; P = 0.004), obesity (HR, 0.56; 95% CI, 0.340.911.69; P = 0.018), and ECOGPS (HR, 1.89; 95% CI, 1.512.39; P < 0.001) as prognostic variables of interest to be included in the multivariable analysis. Presence of background liver cirrhosis did not impact on OS (P=0.917). The multivariable Cox regression model, adjusted for these variables in the training cohort, confirmed that patients classified FIg. 1. Patient flow. N refers to number of patients. (A) Patient flow for patients included in the ENSCCA registry. (B) Patient flow for patients included in the SEER registry. A Patients included in the ENS-CCA registry N=1,820 Patients diagnosed with iCCA N=810 Eligible patients (ENS-CCA cohort) N=554 Training set (N=141) Internal validation set (N=433 Excluded (N=1,010) • Hilar cholangiocarcinoma (N=609) • Distal cholangiocarcinoma (N=309) • Mixed HCC-CCA (N=32) • Not specified (N=60) Excluded (N=256) • No survival/staging data available (N=256) B Patients included in the SEER registry Patients diagnosed with iCCA N=15,601 Eligible patients (SEER cohort) N=4,171 External validation set (N=4,171) Excluded (N=11,430) • No staging data available (N=11,421) • No survival data available (N=9) Hepatology, June 2021LAMARCA ET AL. 2318 in group C (liver metastases) as per the mAJCC v.7 had a worse outcome than patients with early stage (group C [vs. group A] HR, 2.53; 95% CI, 1.185.42; P = 0.017). These findings were validated in the internal validation cohort (group C [vs. group A] HR, 2.93; 95% CI, 2.044.19; P<0.001; Supporting Information S3). SeNSItIVIty aNalySIS: eNSCCa RegIStRy For the sensitivity analysis, only the 75 patients with pT2bN0 were included in group C (Table 3), whereas patients with T2bN1 disease were classified as group B (128 patients). When taking this approach, multivariable Cox regression analysis applied to the whole series confirmed that liver metastases had a prognostic effect, which was independent from lymph node status (group C [vs. group A] HR, 2.51; 95% CI, 1.763.56; P<0.001; Supporting Information S4). When the outcome of patients with T2bM0 disease were analyzed according to N status (total of 114 patients; 75 T2bN0 and 39 T2bN1), N1 disease was shown to be associated with worse OS (median OS for patients with T2bN0 was 11.82 months [95% CI, 7.8920.19], median OS for patients with T2bN1 was 8.99 months [95% CI, 5.0214.61]; T2bN1 [vs. T2bN0] HR, 1.68; 95% CI, 1.102.57; P=0.015). These two observations supported our analysis to continue with the originally proposed definition of group C (T2b, any N, M0). taBle 2.patient Baseline Characteristics and Summary of treatments Received (eNSCCa Registry) Patient Characteristics Whole ENSCCA Series (N=574) Training Cohort (N=141) Internal Validation Cohort (N=433) P Value (Training vs. Internal Validation)N % N % N % Sex Female 279 48.61 88 62.41 191 44.11 <0.001 Male 295 51.39 53 37.59 242 55.89 Age (years) Median (range) 66.16 (2692) 65.83 (2890) 66.15 (2692) 0.4462 Ethnicity Caucasian 539 93.90 122 86.52 417 96.30 <0.001 Other 20 3.49 7 4.97 13 3.01 Not reported 15 2.61 12 8.51 3 0.69 Obesity Yes 116 20.21 28 19.86 88 20.32 0.693 Diabetes mellitus Yes 116 20.21 27 19.15 89 20.55 0.709 Liver cirrhosis Yes 53 9.23 3 2.13 50 11.55 <0.001 Primary sclerosing cholangitis Yes 10 1.74 0 0.00 10 2.31 0.130 ECOGPS 0 241 41.99 22 15.60 219 50.58 <0.001 1 206 35.89 58 41.13 148 34.18 2 78 13.59 35 24.82 43 9.93 3 43 7.49 24 17.02 19 4.39 4 5 0.87 2 1.42 3 0.69 Not reported 1 0.17 0 0 1 0.23 Patient treatment N % N % N % Previous surgery Yes 271 47.21 8 5.67 263 60.74 <0.001 Adjuvant treatment* Yes 49 8.54 1 0.71 48 11.09 0.314 Tumor recurrence Yes 113 19.69 7 4.96 106 24.48 <0.001 Clinical trials Yes 37 6.45 21 14.89 16 3.70 <0.001 Palliative chemotherapy Yes 226 39.37 85 60.28 141 32.56 <0.001 N refers to number, % to percentage. *Adjuvant treatment was not standard of care at the time these patients were treated. Chisquare, Fisher’s exact test, and t test P values are provided (as appropriate). Hepatology, Vol. 73, No. 6, 2021 LAMARCA ET AL. 2319 eXteRNal ValIDatIoN: SeeR RegIStRy Among 15,601 records provided by the SEER database, 4,171 were deemed eligible (Fig. 1B); their baseline and staging characteristics are summarized in Supporting Information S5. All eligible patients were diagnosed between 2010 and 2015. Median followup was 8 months (range, 083; IQR, 218). Median OS was 10 months (95% CI, 910; 3,434 events; 82.33% of patients), with 17.31% of patients classified in group C (liver metastases). Univariate survival analysis confirmed that patients classified in group C (liver metastases) as per the mAJCC v.7 had a poorer outcome than patients with early stage (group C [vs. group A] HR, 1.88; 95% CI, 1.682.09; P<0.001; Supporting Information S1D). Since obesity and ECOGPS data was not available, multivariable analysis could not be performed. oUtCoMeS FoR eaCH Stage gRoUp Figure 2 summarizes patients’ outcome for each disease stage, following both the standard AJCC v.7 (Fig. 2A) and the mAJCC v.7 (Fig. 2B) for ENSCCA (whole population). Outcomes of mAJCC v.7 in the SEER cohort are also shown (Fig. 2C). The updated mAJCC v.7 classification in the ENSCCA cohort (Fig. 2B) and SEER registry (Fig. 2C) showed that compared to stage I disease, risk of death steadily increased through stage progression (stage I > stage II [excluding T2bN0M0] > stage III>stage IVa [excluding T2bN1M0]>liver metastases [T2bN0/1M0]>stage IVb). Data from the ENSCCA registry (Fig. 2B) showed that when group C was used as the reference group, patients diagnosed with earlystage disease group A (stages IIII) had a lower risk of death than group C (stage I [vs. liver metastases]; HR, 0.28; 95% CI, 0.190.40; P < 0.001; stage II [vs. liver metastases]; HR, 0.48; 95% CI, 0.280.81; P=0.007). Compared to group C, groups B and D showed a trend toward longer and shorter survival, respectively, but differences did not reach statistical significance (P=0.118 and P=0.247, respectively). Survival analysis confirmed similar trends in the SEER registry (Fig. 2C). Patients diagnosed with stage I and stage II had a lower risk of death compared to group C. Differences between group A/ stage III and group C (reference category) did not reach statistical significance (P = 0.302). Similar to what had been identified in the ENSCCA cohort, group B (P=0.016) and group D (P<0.001) showed longer and shorter survival compared to group C, respectively. taBle 3.Staging of patients: aJCC v.7 and proposed maJCC Classification (eNSCCa Registry) Staging of Patients Whole ENSCCA Series (N=574) Training Cohort (N=141) Internal Validation Cohort (N=433) N % N % N % AJCCv.7 Stages IIII (including T2bN0M0; liver satellite lesions) 267 46.52 43 30.50 224 51.73 Stage IVa (including T2bN1M0) 128 22.30 28 19.86 100 23.09 Stage IVb (distant mts) 179 31.18 70 49.65 109 25.17 mAJCC Group A: stages IIII (excluding T2bN0M0) 192 33.45 13 9.22 179 41.34 Group B: stage IVa (excluding T2bN1M0) 89 15.51 20 14.18 69 15.94 Group C: stage T2bN0/1M0: liver mts 114 19.86 38 26.95 76 17.55 N0 75 30 45 N1 39 8 31 Group D: stage IVb 179 31.18 70 49.65 109 25.17 mAJCC (sensitivity analysis) Group A: stages IIII (excluding T2bN0M0) 192 33.45 13 9.22 179 41.34 Group B: stage IVa (including T2bN1M0) 128 22.30 28 19.86 100 23.09 Group C: stage T2bN0M0: liver mts 75 22.30 30 21.28 45 10.39 Group D: stage IVb 179 31.18 70 49.65 109 25.17 N refers to number, % to percentage. Abbreviation: mts, metastases.