National Trends in the Use of Neoadjuvant Chemotherapy for Hormone Receptor-Negative Breast Cancer: A National Cancer Data Base Study.

BACKGROUND: Neoadjuvant chemotherapy (NAC) downstages tumor size and nodal disease. This study evaluates national practice patterns of NAC use in hormone receptor-negative breast cancer.

METHODS: We identified patients in the National Cancer Data Base (NCDB) with hormone receptor-negative invasive breast cancer (2004-2012). Univariate and multivariable logistic regression was used to assess associations and trends across time.

RESULTS: Of 171,985 patients, 130,723 (76.0%) received chemotherapy and 41,262 (24.0%) did not. Chemotherapy use was higher in young patients and higher T- and N-stage disease (all p < 0.001). Of those patients treated with chemotherapy, 23,165 (17.7%) received NAC and 107,558 (82.3%) received adjuvant chemotherapy (AC). NAC use increased from 2004 to 2012 (13.0-23.5%; adjusted odds ratio [aOR] 1.42; p < 0.001). Higher clinical T stage (ORs 3.63, 11.81, and 22.34 for cT2, cT3, and cT4a-c, respectively, vs. cT1) and cN+ disease (OR 2.86) [each p < 0.001] were associated with NAC, as were younger patient age and better Charlson-Deyo comorbidity score. Furthermore, BCS rate was higher in the NAC group in cT2 and cT3 tumors (aOR 1.17 and 1.45, respectively; both p < 0.001). In patients with cN+ disease, NAC converted 43.7% to pN0. Less extensive axillary surgery (one to five nodes removed) was more likely in cN+ patients treated with NAC (aOR 1.66; p < 0.001).

CONCLUSIONS: In hormone receptor-negative breast cancer, chemotherapy was mostly administered adjuvantly, but neoadjuvant use increased over time and was more likely in younger patients and higher T- and N-stage disease. Node-positive patients treated with NAC were less likely to have pathologically positive nodes and more likely to have less extensive axillary surgery.