Analysis of the GERCOR index in KRAS Exon2 WT patients with mCRC treated with salvage-line cetuximab-based chemotherapy: HGCSG0901.
781 Background: The GERCOR index (GI) based on performance status and serum LDH was reported to be useful to predict survival for patients with previously untreated mCRC. However, in the salvage setting, the validity of the GI has not been reported in patients treated with cetuximab (Cmab)-based chemotherapy. Methods: 269 patients with mCRC treated with Cmab contained chemotherapy were retrospectively registered from 27 centers in Japan. This analysis was included in the KRAS Exon2 wild type patients who were refractory to or intolerant of 5-FU / irinotecan/ oxaliplatin and were never administered anti-EGFR-antibody. Univariate and multivariate analysis for overall survival (OS) were performed using patient characteristics. Survival analyses were performed with the Kaplan-Meier method, log-rank test and the Cox proportional hazards model. The analysis was also designed to determine whether the GERCOR index could be extended to progression-free survival (PFS). Results: All data were available for prognostic categorization in 132 patients. Median OS and PFS were 9.8 and 4.3 months. The distribution and median OS / PFS for GI were as follows: low risk (L)(n = 28; 17.9/3.8 months), intermediate risk (I)(n = 52; 12.2/5.0 months), and high risk (H)(n = 52; 7.5/4.1 months). For OS, there was significant difference between L and H (p < 0.001) and between I and H (p < 0.001), but not between L and I (p = 0.076). For PFS, there was significant difference between I and H (p = 0.017), but not between L and I (p = 0.407), and between L and H (p = 0.222). In the Cox multivariate analysis, GI showed an independent prognostic impact (L vs. I ; HR 2.195, p=0.003 / L vs. H ; HR 4.028, p<0.001), but not predictive impact (L vs. I ; HR 0.987, p=0.958 / L vs. H ; HR 1.314, p=0.268). Conclusions: In this analysis, GI might be a prognostic factor in salvage treatment with Cmab-based chemotherapy.