Sex difference in patients with biliary tract cancer receiving chemotherapy: Post hoc analysis of ABC-01, -02, -03, -04, BILCAP

517 Background: The relationship between toxicity from chemotherapy and clinical outcome in biliary tract cancer (BTC) is uncertain. Aim: This post hoc analysis evaluated differences by sex in the frequency of adverse events (AEs) and overall survival (OS) and its impact on progression-free survival (PFS)/recurrence-free survival (RFS) for BTC patients. Methods: Individual patient data were retrieved from ABC -01, -02, -03, -04, and BILCAP study. AEs were graded according to National Cancer Institute's Common Toxicity Criteria v 4.02 and odds ratios along with 95%CI and p-values derived from logistic regression were used to assess the effect of sex on the risk of AEs. Time to event outcomes were evaluated using Cox regression and plotted using Kaplan-Meier plots. All statistical tests were two-sided. Results: Overall 994 patients-data were examined: 86 in ABC-01, 324 in-02, 124 in -03, 13 in -04 and 447 in BILCAP. A total of 484 (49%) were males (M) and 510 (51%) were females (F). 770 patients were evaluable for AEs because a total of 224 patients in BILCAP study belonged to the observation group. Urinary tract infection (M, 1.6%; F, 5.5%), nausea (M, 50.7%; F, 69.9%), vomiting (M, 29.1%; F, 46.1%), alopecia (M, 11.3%; F, 27.3%), are dominant in F, hyperbilirubinaemia (M, 36.7%; F, 29.1%) and thrombocytopenia (M, 43.1%; F, 34.3%) and hiccups (M, 2.4%; F, 0.5%) are dominant in M at any grade. Vomiting (M, 3.5%; F, 7.0%) and fatigue (M, 4.0%; F, 8.5%) are higher in F than in M for grade 3-5. The median OS (M, 16.2 months (Mo); F, 17.5 Mo), PFS (M, 6.4 Mo; F, 6.5 Mo) and RFS (M, 20.8 Mo; F 19.4 Mo) were similar. Amongst the subgroup of patients with gallbladder, F achieved longer OS (M, 11.5 Mo; F 13.3 Mo, 0.73 (95%CI:0.54,0.99), p = 0.041) and RFS than M (M, 20.8 Mo; median PFS for F not reached, HR:0.52 (95%CI:0.27,1.02), p = 0.057). Conclusions: Females with BTC have tended to have more AEs, especially grade 3+. Although no difference was observed in OS, PFS, and RFS between males and females for the overall cohort of patients, females with gallbladder cancer had an improved OS and RFS compared with males. These findings suggest, in BTC, sex may play a role when designing clinical trials as well as in making treatment decisions.