Molecular class as a predictor of locoregional and distant recurrence in the neoadjuvant setting for breast cancer.

BACKGROUND: The molecular subtype by hormone receptor status predicts recurrence in the adjuvant setting. Here, we report recurrence patterns by molecular subtype following neoadjuvant chemotherapy (NACT) to identify subgroups prone to recurrence.

MATERIALS AND METHODS: We retrospectively analyzed 331 patients receiving NACT plus lumpectomy and whole breast radiation therapy (RT) (n = 155), or mastectomy with (n = 122) or without (n = 50) adjuvant RT. Tumors were classified by immunohistochemical (IHC) surrogate markers into luminal A (strong ER+/PR+; HER2-), luminal B (weak-to-moderate ER+/PR+; HER2-), HER2 (HER2+), and triple-negative/basal subtypes.

RESULTS: The median follow-up was 43 months (range 10-104). The 5-year disease-free survival (DFS) was 71.4, 70.1, 70.4, and 62.1% for luminal A, luminal B, HER2, and basal subtypes, respectively. The 5-year distant recurrence rates were 25.8, 28.7, 28.7, and 35.2%. The 5-year locoregional recurrence rates were 3.8, 1.6, 1.3, and 4.2%. Molecular class (p = 0.003) and pathologic complete response (pCR; p = 0.004) predicted distant recurrence, DFS, and overall survival (OS). Only the omission of adjuvant RT following mastectomy (p = 0.006) predicted locoregional recurrence.

CONCLUSIONS: IHC subclassification and pCR predict distant failure, DFS, and OS in the neoadjuvant setting. While not predictive of locoregional recurrence, the total number of events were small. More work is needed to define if molecular class can predict patients at risk for locoregional recurrence.