OBJECTIVETo investigate the relationship between breast cancer molecular classification and prognosis.

METHODSFrom January 2002 to December 2003, 708 female primary breast cancer patients with a mean age of 53 years old were retrospectively analyzed. The classification of breast cancer was according to the immunohistochemical results of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor (HER2) status. Molecular classification definitions included highly endocrine responsive, incompletely endocrine responsive, triple negative, and HER2 positive. The prognosis among different molecular classifications of breast cancer was investigated. The survival rates of different classifications were compared by Log-rank test.

RESULTSThe proportion of highly endocrine responsive, incompletely endocrine responsive, HER2 positive and triple-negative breast cancer was 33.2% (235/708), 23.6% (167/708), 21.3% (151/708) and 21.9% (155/708). The follow-up period were from 3 to 68 months with a median of 40.2 months. A total of 100 cases were identified to had disease recurrence or death. Factors affecting the prognosis were tumor size, axillary lymph node status, molecular classification, adjuvant radiotherapy and adjuvant endocrine therapy by univariate analysis. Multivariate analysis revealed that the molecular classification and lymph node status were the independent prognostic factors with the hazard ratio 1.205 (P = 0.047) and 4.512 (P = 0.000), respectively. Survival analysis showed that highly endocrine responsive breast cancer was with superior prognosis versus others.

CONCLUSIONSMolecular classification of breast cancer is an independent predictor of prognosis. Breast cancer patients classified as highly endocrine responsive subtype have the best outcome.