Surgical margin status and survival outcomes of breast cancer patients treated with breast-conserving surgery and whole-breast irradiation after neoadjuvant chemotherapy

Abstract

Purpose: The definition of "no tumor on ink" is generally applied for clear resection margin (RM) after breast-conserving surgery (BCS). However, few studies reported the effect of RM in the setting of neoadjuvant chemotherapy (NAC). We investigated the association between RM status and survival outcomes for those who underwent BCS after NAC for breast cancer.

Methods: We retrospectively reviewed the data of 2,803 patients who underwent BCS and whole-breast irradiation after NAC between January 2008 and December 2016 from three institutions in South Korea.

Results: The 786 patients in the pathologic complete response group (R_pCR) had significantly longer local recurrence-free survival (LRFS) than the 1,949 patients in clear or close RM and non-pCR group (R₀) and the 68 patients in involved RM and non-pCR group (R₁) (vs. R₀, p = 0.001; vs. R₁, p = 0.049). Patients in R₀ showed no benefit in LRFS compared to R₁ on both log-rank test (HR = 1.20; 95% C.I., 0.49-2.93; p = 0.692) and Cox regression analysis (HR = 2.05; 95% C.I., 0.64-6.58; p = 0.227). Subgroup analysis according to tumor subtypes revealed that there was no significant difference in LRFS, distant metastasis-free survival, and recurrence-free survival between the R₀ and R₁ group. Additionally, among 286 patients with pCR with residual ductal carcinoma in situ (DCIS) alone, RM status was not significantly associated with LRFS.

Conclusion: Clear RM of specimen does not have benefit on LRFS after NAC. Additionally, for the patients showing pCR with residual DCIS in the breast, margin involvement also did not affect the risk of local recurrence.

Keywords: Breast neoplasms; Margins of excision; Mastectomy, segmental; Neoplasm recurrence, local.