Participation in Cancer Pharmacogenomic Studies: A Study of 8456 Patients Registered to Clinical Trials in the Cancer and Leukemia Group B (Alliance)

Background: Clinically annotated specimens from cancer clinical trial participants offer an opportunity for discovery and validation of pharmacogenomic findings. The purpose of this observational study is to better understand patient/institution factors that may contribute to participation in the pharmacogenomic component of prospective cancer clinical trials.

Methods: Patient demographic information (age, sex, self-reported race) and institutional characteristics (CALGB/CTSU site, "diversity," and accrual) were evaluated for 8456 patients enrolled in seven CALGB phase III studies with a pharmacogenomic component. All statistical tests were two-sided.

Results: The majority of patients (81%) consented to participate in the pharmacogenomic component. However, in a multivariable analysis, site (CALGB vs CTSU) and "institutional diversity" (percent minority cancer patients on national trials) were statistically significantly associated with participation. For both whites and nonwhites, patients from CALGB sites were more likely to participate compared with patients from CTSU sites (whites: odds ratio [OR] = 2.26, 95% confidence interval [CI] = 1.68 to 3.04, P < .001; nonwhites: OR = 1.79, 95% CI = 1.52 to 2.11, P < .001). However, as "institutional diversity" increased, the likelihood of participation in the pharmacogenomics component decreased for both white (OR = 0.94, 95% CI = 0.91 to 0.97, P < .001) and nonwhite patients (OR = 0.90, 95% CI = 0.81 to 1.00, P = .05).

Conclusions: Most clinical trial cancer patients across geographical, racial, and practice settings are willing to participate in pharmacogenomic studies. However, to promote equitable benefit to the larger cancer community, optimization of both patient and institutional participation are needed. Institutional factors may be even more compelling than patient demographics. Prospective studies are needed to identify and address barriers/incentives to participation in pharmacogenomic research at the patient, clinician, and institutional levels.