Comparative Effectiveness Research: The Impact of Biologic Agents in Ethnic Minorities With Metastatic Colorectal Cancer

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Abstract

Micro-Abstract

The survival advantage of biologic agents for patients treated for metastatic colorectal cancer was generated from trials from a predominantly white population. We carried out a comparative effectiveness research study in our center that caters to an ethnic minority population. Using a robust multi variable analysis we demonstrate that black and Hispanic patients do not enjoy a similar benefit.

Background

Biologic agents have improved the outcomes of patients with metastatic colorectal cancer (mCRC). However, the clinical trials included a predominately white population (85%), with Hispanic and black patients underrepresented. Thus, the real world benefit for the latter remains unknown. Comparative effectiveness research is a tool allowing for this exploration.

Patients and Methods

The demographic and clinical characteristics of patients treated for mCRC from 2000 to 2011 were extracted from the medical records of Montefiore Medical Center. A semiparametric accelerated failure time model was used to assess the survival differences between patients receiving chemotherapy (CT) alone versus CT plus biologic agents (CBT).

Results

Of the 290 patients (black, 45.9%; Hispanic, 26.2%; and white, 27.9%), 53.8% received biologic agents. The median overall survival was 15.2 months in the CT-alone group and 25.6 months in CBT group (P = .004). On univariate analysis, a lower number of metastatic sites, carcinoembryonic antigen < 41 ng/mL, and more lines of CT were associated with improved overall survival. In a propensity score-based analysis of the entire cohort, CBT offered a survival benefit compared with CT alone (increased median survival, 1.44-fold; 95% confidence interval [CI], 1.11-1.86; P = .038). The results of the subgroup analysis suggested a survival benefit for white patients (2.01; 95% CI, 1.26-3.23; P = .031) but not for Hispanic (1.42; 95% CI, 0.91-2.20; P = .370) or black (1.12; 95% CI, 0.76-1.66; P = .596) patients.

Conclusion

In the present cohort, CBT was associated with longer survival, with the effect mainly driven by the outcomes for white patients, with black patients not appearing to benefit. These data are provocative and warrant further confirmation. Efforts to increase ethnic minority patients' enrollment in clinical trials is required to prospectively define the benefit from novel therapies.

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