The outcome of special histologic types of triple-negative breast cancer (TNBC).

1122 Background: Triple-negative breast cancer (TNBC) is a heterogeneous disease. Knowledge of the outcome of special histological subtypesof TNBC can facilitate tailored adjuvant treatment. The aim of the study was to determine recurrence rate and overall survival of special histological subtypes of TNBC in order to select those with excellent and the worst prognosis. Methods: Of 4,563 consecutive breast cancer patients diagnosed in Cancer Center and Institute of Oncology in Warsaw, Poland, between the years 2005 and 2008, 502 patients (9%) were TNBC (ER-/PR-/HER2-negative). Median follow-up was 7 years (range 5–9 years). 426 cases with known histological types were selected and analyzed in terms of the disease free and overall survival using the Kaplan-Meier method. Competing risk analysis was performed in order to assess the risk of recurrence and the comparison between types. Results: From 426 TNBC subtypes, 352 (82%) cases were classified as ductal not otherwise specified (NOS), 21 (5%) were classified as lobular, 17 (4%) were classified as metaplastic, 10 (2.3%) were classified as medullary, 7 (1.6%) as apocrine, 6 (1.4%) as papillary, 4 (0.9%) as neuroendocrine, 2 (0.5%) as cribriform and 2 (0.5%) were classified as mucinous. 5-year DFS and OS of ductal NOS type was 73% and 62%, respectively. 5-year DFS was the best for patients with apocrine (100%), medullary (100%) and neuroendocrine (100%) types while it was the worst in papillary (50%) and lobular (68%) TNBC. 5-year OS was the best in apocrine (90%) and medullar (100%) types and was the worst in papillary (17%) and lobular (61%) types. In metaplastic TNBC 5-year DFS and OS was 79% and 65%, respectively. Taking into account competing risk of death and different clinical stages of the disease, the risk of recurrence was the highest in patients with lobular TNBC (HR=2.83, p=0.04). Conclusions: The diagnosis of special types of TNBC is associated with different outcome if compared with ductal NOS type. Medullary and apocrine types had excellent prognosis while lobular TNBC seems to be the most aggressive and requires intensive treatment. Histological special type of TNBC should be taking into consideration when choosing adjuvant treatment, apart from specified other prognostic factors.