A model of comparative effectiveness research (CER): The impact of biologic agents in a cohort of patients from ethnic minorities with metastatic colorectal cancer (mCRC).

Abstract

591 Background: The role of biologic agents in the treatment of mCRC has been studied in clinical trials. These studies included ≥ 90% patients (pts) of white race. Hispanics and blacks were largely underrepresented. CER allows exploration of the impact of biologic agents in a cohort composed largely of pts from minorities. We present the results of a cohort of pts served by Montefiore Einstein Cancer Center (MECC) in Bronx, NY. Methods: Pts diagnosed and treated for mCRC from January 2000 to December 2011 were identified using data from the MECC Cancer Registry. Pts demographic and clinical characteristics were extracted from pts medical records. A Cox proportional–hazard model was used to assess survival differences between pts treated with chemotherapy alone vs. pts treated with chemotherapy plus biologics. Results: A total of 293 pts where identified; 45% were black, 27% were Hispanic, and 28% were white. Of the pts receiving biologics, 90% received bevacizumab and 50% received cetuximab or panitumumab. The median overall survival was 15.2 months in the chemotherapy alone group and 25.6 months chemotherapy + biologics group (p=0.003). Univariate analysis showed that 1 metastatic site vs. ≥ 2, CEA <40 ng/mL, receiving ≥ 2 lines of chemotherapy and exposure to biologics were independently associated with longer survival. Multivariate analysis of the whole cohort (n=290), which included all ethnic groups, showed that exposure to biologics offered a survival benefit (HR of 0.70, 95%CI 0.52–0.93, p=0.02), after adjusting for gender, age, CEA, number of metastatic sites and lines of chemotherapy received. Subgroup analysis based on ethnicity showed survival benefit for Whites (HR of 0.38, 95%CI 0.22–0.66, P=0.001) but not for Hispanics (HR of 0.65, 95%CI 0.35–01.23, p=0.18) nor Blacks (HR of 1.04, 95%CI 0.63–1.70, p=0.87). Conclusions: In this cohort weighted heavily towards ethnic minorities, the addition of biologics to chemotherapy was associated with longer survival, an effect mainly driven by whites. Hispanics and blacks did not seem to benefit from exposure to biologics. An effort should be made to include minority pts in ongoing clinical trials.