Racial and ethnic disparities in conversion to mastectomy following lumpectomy

Advances in contemporary breast cancer care (e.g., early detection, increased use of preoperative chemotherapy, and updated SSO-ASTRO margin guidelines) have the collective potential to influence successful breast conservation. We evaluated contemporary trends in conversion to mastectomy (lumpectomy followed by definitive mastectomy) among women with breast cancer undergoing initial lumpectomy.

Women with unilateral clinical stage 0-III breast cancer were identified from the National Cancer Database (2009-2019). Treatment sequence was categorized into surgery first or neoadjuvant chemotherapy (NACT) followed by surgery. We used a multivariable logistic regression model to calculate the predicted probability of conversion to mastectomy across diagnosis year and race and ethnicity, controlling for socio-demographic and clinical factors. We then calculated the relative change in conversion to mastectomy over time for each race and ethnic group.

The study included N = 1,543,702 women. Approximately 9.2% received NACT. Conversion to mastectomy differed significantly between those who underwent surgery first (10.6%) versus women who received NACT (6.1%, p < 0.0001). For those who underwent surgery first, success of breast conservation differed significantly by race/ethnicity. During the study period, White women had a relative decrease of 7.6% (95% CI - 10.58, - 4.59), while Black women had a relative increase of 8.9% (95% CI 1.53, 16.19) in predicted probability of conversion to mastectomy.

Over the past decade, Black women deemed candidates for initial lumpectomy were more likely to be converted to mastectomy when compared to White women. A greater understanding of contributing factors is needed to improve disparities in successful breast conservation.