Real-world outcomes in young women with breast cancer treated with neoadjuvant chemotherapy.

Breast cancer in young women has been shown to have an aggressive behavior and worse prognosis. Studies evaluating young women enrolled in clinical trials of neoadjuvant chemotherapy have shown that age is a determinant factor in the achievement of a pathological complete response (pCR). In this study, we sought to analyze the outcomes of young patients treated with neoadjuvant chemotherapy at a single institution. 1639 patients treated with neoadjuvant chemotherapy were included. 316 patients ≤40 years were compared with 1323 patients aged >40 years regarding the achievement of a pCR (defined as no invasive residual tumor in the breast or lymph nodes). Disease-free survival (DFS) and overall survival were compared between groups according to pCR status and subtype, defined by hormone receptor (HR) and HER2 status. Young women were more likely to have a pCR than their older counterparts (37.4 vs. 26.3 %, P < 0.001). This difference was significant both for HR+/HER2- and triple-negative (TN) tumors. Young age and achieving less than pCR were associated with a greater chance of recurrence for the entire population. Age was not an independent factor for recurrence in TN and HER2+ disease. However, being younger than 40 increased recurrence risk in HR+/HER2- tumors. The achievement of a pCR was not associated with improved DFS in young women with HR+/HER2- tumors. Although young women have a high rate of pCR, they also have a worse prognosis. In a real-world clinical setting, the achievement of a pCR was an independently significant protective factor for recurrence across all subtypes and ages, except for HR+, HER2- disease in young women.