403P First-line anti-EGFR therapy, patient characteristics and survival: Results from South Australian (SA) metastatic colorectal registry (mCRCR)

Abstract

Treatment of mCRC is guided by clinical and molecular features which include side of primary, RAS, BRAF and MMR status. For left sided RAS WT mCRC survival is optimized by using first-line anti-EGFR anti-bodies combined with chemotherapy. We aim to assess the use of first-line anti-EGFR/chemotherapy (FaEC) combinations in patients with mCRC and assess for differences between cetuximab (C) and panitumumab (P) using the SA mCRCR. This real word registry has collected data from all patients diagnosed with mCRC in SA prospectively since 2/2006. We compared C and P in RAS WT patients, and those treated with bevacizumab (B) from 2006 and those treated since January 2015 when FaEC was funded in Australia. Survival was analysed using the Kaplan Meier method. Of the 5537 patients currently entered onto the registry, 1313 had RAS status recorded and 245 received FaEC (167/68% since 2015). 1068 patients received B (52% KRAS WT). Table summarises patient characteristics and median OS for FaEC (C or P) and B. Overall there was no statistical difference in survival for C v P (p=0.125). Patients entered from 2015 had mostly similar patient characteristics including significant use in right sided primary (24% v 20% respectively).Table: 403PChemo/C (139)Chemo/P (106)Chemo/B (1068)Median age (range)65.3 yrs (24-87)60.1 yrs (26-89)64.6 (20.5-93)Male66.2%64%61%Oxaliplatin15%43.4%70%Irinotecan59%46.2%15.5%Stage 4 at diagnosis47.5%64.2%67.5%Left primary65.5%77.4%58%Liver mets only38.1%42.5%37.2%Lung mets only5.8%9.4%8.7%BRAF MT7.9%2.8%7.3%Liver resection6.5%14.2%9.8%Median OS (95% CI)21.6 mths (16.7-26.4)25.3 mths (20.8-29.7)22.7 mths (21-23.9) Open table in a new tab When comparing C & P in first-line therapy, C was more often combined with irinotecan chemo. There were lower rates of liver resection and higher right primary and BRAF MT in patients treated with C which may explain the numerically lower median overall survival.