P-165 First-line treatment with CET/PAN vs. BEV in elderly patients with RAS WT mCRC: A multicenter real-world observational study by the Japanese Society for Cancer of the Colon and Rectum

Elderly patients are often underrepresented in clinical trials for metastatic colorectal cancer (mCRC), and there is limited evidence on the efficacy of anti-epidermal growth factor antibody (cetuximab or panitumumab [CET/PAN]) bevacizumab (BEV) this population. We aimed to compare these regimens elderly with unresectable RAS wild-type (WT) left-sided cancer. retrospectively analyzed data who received CET/PAN BEV plus 5-fluorouracil-based doublet chemotherapy as first-line treatment WT mCRC at 24 Japanese institutions between January 2013 December 2016. Progression-free survival (PFS) overall (OS) were compared a non-elderly cohort ( < 70 years) an (≥70 by multivariate Cox regression analysis. Of 935 potentially eligible patients, 722 included study. The 562 (77.8%), 160 (22.2%). In PFS (median 13.3 months [12.2-15.0] vs. 12.4 [95% CI 10.7-14.2]; adjusted HR 0.89 [0.75-1.06]) OS 36.8 [33.6-40.1] vs 30.9 [27.2-38.0]; 1.01 [0.82-1.24]) similar BEV. contrast, was inferior receiving (13.0 [10.1-15.5] 10.2 [6.7-11.0]; 0.66 [0.48-0.92]). Moreover, additional analysis age suggested worsening aged 70-74 years (HR 0.78 [0.64-0.96]) 75 older 0.49 [0.28-0.87]). also shorter than those 33.0 [26.5-38.2] 21.8 [15.6–31.4]; 0.55 [0.37-0.80]). Discontinuation due adverse events more common BEV, especially (non-elderly cohort, 9.4% 5.4%; 23.9% 11.9%).The proportion undergoing conversion surgery higher group regardless age, but lower 22.5% 15.7%; 10.9% 5.5%). may have be toxic These findings should considered when treating cancer, appropriate management side effects needed CET/PAN.