Clinicopathologic and prognostic features of triple-negative breast cancer analyzed in registration data of the Japanese Breast Cancer Society, 11705 cases

Abstract

e22122 Background: Triple-negative (TN) breast cancers which are negative for ER, PgR, and HER2 by immunohistochemistry are associated with a poor prognosis. To clarify the characteristics of TN tumors, the data of the registration committee of the Japanese Breast Cancer Society were analyzed with respect to clinicopathologic factors, response to neoadjuvant chemotherapy (NAC) and prognosis. Methods: Of 14,748 cases that were registered in 2004, 11,705 cases (79.4%) were examined for ER, PgR, and HER2 status, which was based on local institute. In the 2,331 cases of all registered cases, the prognosis and details of the treatment were analyzed with 47.8 months as median follow-up period. In 184 cases (7.9%), NAC was mainly performed using anthracycline and taxane based chemotherapy. Results: Luminal A type with positive for ER and/or PgR and negative for HER2 was most prevalent (53.8%), followed by TN type (15.5%). TN cancers were diagnosed at a slightly advanced stage and more of the cases had lymph node metastases compared to other types. Mucinous or tubular carcinoma was frequently seen in the Luminal A type. Squamous cell, spindle cell carcinoma, or metaplastic carcinoma with bone/cartilage metaplasia was found in only TN type. The HER2 type and TN type had statistically worse outcome compared to Luminal type in DFS and OS (P<.0001 and P<.0001, respectively). Pathological response rate of NAC, including grade 2 and 3, was higher in TN tumor as 51.5 % (22/53) than in Luminal A tumor as 16.7% (12/72). Responders in TN tumors have a better prognosis than non-responder (P=.0016), but this tendency was not recognized in non-TN tumors (P=.15). Conclusions: The ratio of the TN tumors in Japan was 15–6%. Central reviews of immunohistochemistry, such as ER, PgR, HER2, CK5/6, EGFR etc, will be confirmed in this cohort, for TN tumors are similar to basal-like tumors discriminated by gene- profiling. [Table: see text]