Rare breast cancer: 246 invasive secretory carcinomas from the National Cancer Data Base

Background and Objectives Invasive secretory breast carcinoma (SBC) is a rare subtype of breast malignancy. Methods Cases of SBC and infiltrating ductal carcinoma (IDC) from the National Cancer Database (1998-2011) were queried. Results Patients with SBC (n = 246) and IDC were identified (n = 1,564,068). The group with SBC was younger (age 56.4 ± 16.0 vs. 60.4 ± 13.9 years, P < 0.001), had similar tumor size (19.9 ± 17.8 vs. 21.6 ± 25.5 mm, P = 0.297), more frequently African-Americans (24.1 vs. 14.8 vs. 13.7; P = 0.004), more well-differentiated (32 vs. 18%, P < 0.001) and less likely to be hormone receptor positive (ER: 64 vs. 76%, P = 0.001; PR: 43 vs. 65%, P < 0.001). No differences were found for incidence of node-positivity (32 vs. 34%, P = 0.520) and stage IV presentation (2.4 vs. 3.6%, P = 0.372). Breast conserving surgery (60 vs. 58%, P = 0.405) and hormonal therapy (67 vs. 71%, P = 0.489) rates were similar. Systemic chemotherapy was used less often for SBC (38 vs. 45%, P = 0.035). The overall survival of all patients with SBC was better than all patients with IDC (median not reached vs. 14.8 years, P = 0.025). Conclusion SBC is an uncommon tumor that is often well-differentiated and seen in younger women. Contrary to prior reports, they are frequently hormone receptor-positive. Compared to IDC, overall survival is improved.