Comparative Effectiveness of Chemotherapy in Elderly Patients with Metastatic Colorectal Cancer

463 Background: The management of metastatic colorectal cancer (mCRC) has evolved considerably with advances in chemotherapeutic agents that have led to improved outcomes. Less is known about the benefits of newer agents in the real-world setting. The objective of this study was to evaluate treatment patterns and survival in older, demographically diverse mCRC patients. METHODS Using the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database, we conducted a retrospective cohort analysis of 5931 stage IIIB, IIIC and IV CRC patients diagnosed between 1/1/ 2000 - 12/31/2007, who were >66 years, enrolled in Medicare Parts A and B, and received first-line treatment with 5FU/LV (n=2907), CAP (capecitabine; n=963), FOLFOX (n=1856) or CAPOX (CAP + oxaliplatin; n=205). Date of last follow-up was 12/31/2009. Statistical comparisons were made between 5FU/LV vs. CAP and FOLFOX vs. CAPOX. Cox regression with backward elimination estimated the relative risk of death, adjusting for demographic and clinical factors. RESULTS Compared to 5FU/LV, patients treated with CAP were older (>80 years) at diagnosis (36% vs. 22%; p<.0001) and more likely female (59% vs. 53%; p=.0025), while patients receiving CAPOX were older (>80 years: 12% vs 8%; p<0.05) compared to FOLFOX. The mean time to chemotherapy initiation after diagnosis was similar between CAP and 5FU/LV (76 vs. 71 days) and between FOLFOX and CAPOX (75 vs. 70 days). The mean duration of treatment was longer for 5FU/LV (144 days) vs. CAP (122 days; p<.0001) and comparable between CAPOX (144 days) and FOLFOX (150 days; p=0.2139). The incidence of adverse events (AE) within 180 days after initiation of treatment were higher in patients treated with 5FU/LV (37%) vs. CAP (9%); p<.0001 and in FOLFOX (58%) vs. CAPOX (44%); p<0.0001. In multivariate analysis there were no significant differences in risk of death between CAP and 5FU/LV, and between CAPOX and FOLFOX ( table ). CONCLUSIONS Overall survival was comparable between CAP and 5FU/LV and between CAPOX and FOLFOX with fewer AEs associated with CAP and CAPOX. This provides real-world confirmation of clinical trial data. [Table: see text].