Her2 positivity and race predict higher mastectomy rates: a SEER database analysis

Theresa L. Schwartz, Jula Veerapong, Leslie Hinyard

Given the difference in incidence of biologic subtype of breast cancer between black and white women, and the potential disparity in type of surgery in black and white women presenting with early stage breast cancer, this study aimed to examine the odds of mastectomy compared to lumpectomy by molecular subtype in black and white women with size T1 and T2 invasive breast cancer. Using the SEER database, breast operation choice for women over the age of 15 with T1 or T2 tumors between 2010 and 2012 were examined. Tumors were categorized according to the Breast Subtype variable in the SEER database and data were stratified by tumor size and race. Bivariate comparisons and logistic regression models adjusted for age were used. In women with T1 or T2 tumors, mastectomy rates were higher in women with Her2 positive tumors than in those with Her2 negative tumors. When Her2 results are the same among comparison groups, those women with HR positive tumors were less likely to undergo a mastectomy than those with HR negative tumors. In T1 tumors, the magnitude of the association was larger for white women than women of other races. Results suggest there are differences in surgical decision making based on breast cancer subtype in women with T1 or T2 tumors and that race may play a role for size T1 tumors. The strong association between Her2 positive tumors and higher mastectomy rates warrants further investigation.