Patterns of 21-gene assay testing and chemotherapy use in black and white breast cancer patients

Background: In women with early stage, hormone receptor (HR)-positive (HR(+)) breast cancer, the 21-gene recurrence score (RS) assay quantifies recurrence risk and predicts chemotherapy responsiveness. Recent data suggest that not all women with early-stage, HR(+) disease receive this testing. We examined sociodemographic, clinical, and attitudinal factors associated with RS testing receipt and the RS testing effect on chemotherapy use in black and white patients.

Patients and methods: Women with newly diagnosed invasive, nonmetastatic breast cancer were recruited and interviewed to collect sociocultural and health care process data; clinical data were collected from charts. Of the sample (n = 359), 270 had HR(+) disease. Primary analysis focused on those with HR(+) node-negative disease (n = 143); secondary analyses included node-positive women. Logistic regression models evaluated factors associated with receipt of RS testing and chemotherapy.

Results: Among women eligible for the 21-gene assay, 62 patients [43%] received RS testing. In multivariable analysis, older age (odds ratio, 1.04 per 1 year increase; 95% confidence interval, 1.01-1.08) was associated with RS testing after adjustment for covariates. Chemotherapy use was 23%. In multivariable analysis, positive attitudes about chemotherapy and greater risk of recurrence were associated with chemotherapy use (P < .05).

Conclusion: Patterns of genomic testing might vary according to age. Efforts to understand factors associated with low testing rates will be important.