Abstract P6-05-01: Triple Negative Breast Cancer in Korea — Distinct Biology with Different Impact of Prognostic Factors on Survival

Abstract

Abstract Background: Patients with triple negative breast cancer(TNBC) are known to have poor prognosis and derive no benefit from endocrine therapy or targeted treatments. Using a database from a multicenter registry in Korea, we present the clinical features and prognosis for TNBC with other subtypes of breast cancer and clinicopathologic variables that influence the 3-year survival of the TNBC patients. Materials and Methods: From 1993 to 2008, patients diagnosed with breast cancer who were registered to the Korean Breast Cancer Society Registry were analyzed retrospectively. A cohort of 26,767 patients were divided in four groups: luminal A (ER+ and/or PR+, HER2-), luminal B (ER+ and/or PR+, HER2+), HER2 overexpression (ER-, PR-, HER2+), and triple negative (ER-, PR-, HER2-). Clinicopathologic features such as age, tumor size, nodal status, p53, ki-67 expression and survival were evaluated. Results: The luminal A (14437 patients, 53.9%) subtype was the largest in our study sample, as compared with luminal B (3517 patients, 13.1%), ER-/HER2+ (3227 patients, 12%), and TNBC (5586 patients, 21%) subtypes. Compared with luminal A subtype, TNBC correlated with younger age and more aggressive characteristics, such as larger size, more lymph node metastasis, and higher proliferation rate. Moreover, TNBC correlated with poor overall survival and breast cancer-specific survival. The hazard rate showed a peak at 24 months for the TNBC subtype, but after 60 months, the risk was similar to that of the luminal A subtype. Higher T, N stage and histologic grade, and lymphatic and vascular invasion showed poor prognosis in TNBC patients, but on multivariate analysis only histologic grade and ki-67 status were related to poor prognosis. Young age was related to poor prognosis in the luminal A subtype, however, age was not related to prognosis in the TNBC subtype. Of the 5586 TNBC patients, 282 patients (7.11%) expired within 3 years of diagnosis. T and N stage, and grade was significantly associated with prognosis on multivariate analysis. Discussion: TNBC subtype is characterized by a younger age with poorer outcome. However, younger age is not related to prognosis, and mortality risk decreases to that of the luminal A subtype, which is known to have the best prognosis after a few years. The underlying biology of the TNBC subtype is important, and further studies to discover novel biomarkers to predict prognosis and target treatments for the TNBC subtype are necessary. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-05-01.