Rising Bilateral Mastectomy Rates Among Neoadjuvant Chemotherapy Recipients in California From 1998 to 2012

Objective: To study the impact of rising bilateral mastectomy rates among neoadjuvant chemotherapy (NAC) recipients in California. Background: NAC for operable breast cancer (BC) can downstage disease and facilitate breast conservation. We assessed trends in NAC use and surgical procedures in California from January 1, 1998 to December 31, 2012 using statewide population-based cancer registry data. Methods: A total of 236,797 females diagnosed with stage I-III BC were studied. Information regarding NAC, adjuvant chemotherapy (aCT), breast conserving surgery (BCS), bilateral mastectomy (BLM), and unilateral mastectomy (ULM) was abstracted from the medical records. Multivariable polytomous logistic regression was used to estimate odds ratios (OR) of receiving NAC and of type of surgery after NAC. Results: Approximately, 40.1% (94,980) of patients received chemotherapy: 87% (82,588) aCT and 13.0% (12,392) NAC. NAC use more than doubled over time and increased with stage (Stage I, 0.7%; Stage III, 29.9%). Multivariable predictors of NAC treatment were stage (III), younger age (< 40 yrs), Black or Hispanic race/ethnicity versus non-Hispanic White (OR 1.10, 95% confidence interval (CI) 1.05-1.16), and care at a National Cancer Institute (NCI)-designated center (OR 1.70, CI 1.58-1.82). Most NAC recipients (68.4%) had mastectomies, and 14.3% of them underwent BLM. In contrast, 47.9% aCT patients had mastectomies with 7.3% BLM. The only independent predictor of BCS after NAC was care at a NCI-designated center (OR 1.28, CI 1.10-1.49), and of BLM, age < 40 years versus 50 to 64 years (OR 2.59, CI 2.21-3.03), or residence in the highest socioeconomic neighborhood quintile versus lowest (OR 2.10, CI 1.67-2.64). Conclusions: NAC use remains low. Predictors of surgery type after NAC were sociodemographic rather than clinical, raising concern for disparities in care access.