Evaluating gender as a predictive marker for response to bevacizuamb (Bev) in metastatic colorectal carcinoma (mCRC): Pooled analysis of 3369 patients (pts) in the ARCAD database.

Abstract

3539 Background: Previous studies suggest a possible gender-specific response to Bev in mCRC, showing a benefit in males, while the effect in females is less significant. Therefore, we evaluated response to Bev according to gender. Methods: Data from 3369 mCRC patients enrolled on 4 first-line randomized trials testing Bev (2000-2007) were pooled. Association between gender and progression-free survival (PFS)/overall survival (OS) was evaluated by stratified Cox regression model, adjusted for potential confounders. Predictive value was evaluated by interaction (inter.) effect between gender and treatment. In a pre-planned secondary analysis, analyses were stratified using an age cut-point of 60 years (commonly used in breast cancer trials) to evaluate the possible role of menopausal-related effects. Results: OS was not statistically different between males and females (median OS [mOS], 18.8 vs. 17.6 months [mo], adjusted hazard ratio [HRadj], 0.93, 95% confidence interval [CI], 0.84-1.03, p, 0.15) in the overall population. Bev was associated with an improved mOS in males and females, with a 2.3 and 0.6 mo benefit, respectively, as well as an improved PFS. There was no statistically significant interaction effect between gender and treatment (see table). Further stratified by age (< vs. ≥ 60 years), Bev resulted in improved PFS and OS in both genders, at all ages, except for the effect in young females which did not reach statistical significance (see table). Conclusions: Our results confirmed the mOS benefit from addition of Bev to first-line chemotherapy in mCRC in both genders, although the benefit in females was < 1 month. For females under the age of 60, there are uncertainties for mOS benefit from addition of Bev and further evaluation is needed. [Table: see text]