87 Background: A subgroup of RAS wild-type metastatic colorectal cancer patients within the FIRE-3 study consisted of 400 patients. Gaining insight into frequency and effects of weight change among patients treated with FOLFIRI plus either cetuximab or bevacizumab was aim of this analysis. Methods: A subgroup of 400 RAS wild-type metastatic colorectal cancer (mCRC) patients of the FIRE-3 trial were evaluated. Linear mixed effect models were fitted to explore the mean evolution of weight over time. The presence of a breakpoint at month 1 was investigated by the addition of an adequate parameter into the model. A linear evolution was supposed from month 1. In this exploratory analysis, patients were grouped into cohorts according to weight change using the cut off ≥ 5%. Kaplan-Meier estimations and median survival times were analyzed using log-rank testing. Hazard ratios and corresponding 95% confidence interval from univariate Cox proportional hazards were followed by a multivariate analysis. Results: Patients lost in average 0.75 kg during the first month of treatment, whereas body weight increased hereafter 0.43 kg per month. Of note, patients older than 65 years lost most body weight at month one (1.35kg) and gained least hereafter (0.20kg per month). Within this population a weight loss of ≥ 5% was observed to be an independent prognostic factor for both PFS after 3 months (HR 1.72, 95% CI 1.26-2.34, P = 0.001) and OS after 3 months (HR 1.754, 95% CI 1.29-2.39, P < 0.001). This remained significant when adjusted for age, sex, ECOG score, primary tumor side and treatment arm. Conclusions: In the overall RAS wild-type population, weight loss is an independent prognostic factor for survival in patients with RAS wild-type metastatic colorectal cancer patients and may predict the frequency of adverse events. Therefore, we assume that early preventative measures targeted at weight maintenance might contribute to improved outcomes among this population.
P-27 Retrospective observational analysis of p53 mutational status as a prognostic factor in TAS-102 treated metastatic colorectal cancer patients
