Well-documented racial disparities in survival of patients with HER2+ breast cancer diminished after FDA approval of trastuzumab, according to research presented at the 2015 ASCO breast cancer symposium.
A retrospective study identified 32,597 cases of HER2+ breast cancer from the California Cancer Registry, and divided them into early (diagnosed 2000-2006) and late (diagnosed 2006-2012) cohorts. In the early cohort, diagnosed before trastuzumab was available, black patients had an increased risk of mortality (hazard ratio, 1.32; 95% confidence interval, 1.16-1.49), compared with whites. In the late cohort there were no survival differences based on race.
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“Although we were unable to document use of anti-HER2 treatment, the era of adjuvant trastuzumab appears to have attenuated the black/white disparity in HER2-positive breast cancer,” wrote Dr. Vincent Caggiano, hematologist at Sutter Medical Center Sacramento, California, and colleagues in a meeting abstract.
The study analyzed risk of mortality, adjusted for stage, grade, age, and socioeconomic status, for African Americans, Hispanics, Asian/Pacific Islanders, and American Indians, compared with white patients. Considering estrogen-receptor and progesterone-receptor status, the combination of all HER2+ subtypes (ER+/PR+/HER2+, ER-/PR+/HER2+, ER+/PR-/HER2+, ER-/PR-/HER2+), showed increased risk for black patients before 2006. The ER-/PR-/HER2+ subtype showed no racial disparities for either cohort. The highest risk (HR, 1.43; 95% CI, 1.17-1.75) was observed for black patients of the ER+/PR+/HER2+ subtype diagnosed before 2006.