Secretory breast carcinoma: a multicenter clinicopathologic study of 80 cases with emphasis on prognostic analysis and chemotherapy benefit

To investigate clinicopathologic characteristics and prognosis in secretory breast carcinoma (SBC) and to determine chemotherapy benefits stratified by different subgroups.

SBCs and triple-negative invasive ductal carcinoma patients (TN-IDCs) were enrolled from three cancer centers between January 2011 and December 2020. SBCs were further divided into two subgroups: those with triple negativity (TN-SBCs) and those without (non-TN-SBCs). Clinicopathologic characteristics were thoroughly compared among the three subgroups associated with triple negativity. Kaplan–Meier estimates and Cox proportional hazard models were performed for survival analysis.

A total of 80 SBCs and 310 TN-IDCs were included in the study. The TN-SBC subgroup consisted of 35 individuals (43.75%) with mild clinical behaviors and a satisfying prognosis in comparison to non-TN-SBCs and TN-IDCs. In SBCs, N stage (N1 vs. N0: HR = 11.176, 95% CI 0.843–148.132, p = 0.067; N2–3 vs. N0: HR = 30.409, 95% CI 1.378–671.169, p = 0.031), LNR (HR = 23.894, 95% CI 1.614–353.835, p = 0.021), and histological grade (HR = 28.634, 95% CI 2.745–298.703, p = 0.005) were significantly correlated with disease-free survival (DFS). Patients in high LNR group receiving chemotherapy achieved a prolonged DFS (p = 0.025), while chemotherapy did not confer a survival benefit in TN-SBCs of our interest (p = 0.12).

TN-SBC is a unique entity with low malignant potential. Advanced N stage, high LNR, and advanced histological grade are adverse determinants of DFS in SBC. Adjuvant chemotherapy provides superior DFS in high LNR SBCs rather than TN-SBCs, hence it is recommended for high LNR SBCs.