Abstract: Objective To investigate the relationship between molecular subtype and prognosis of invasive ductal carcinoma（IDC） of breast.
Methods Clinical data of 822 patients with clinicopathologically resectable breast IDC in the First Affiliated Hospital of Xi'an Jiaotong University were collected from January 2000 to December 2012. Based on immunohistochemistry， we categorized the breast cancer as the following molecular subtypes：Luminal A， Luminal B， HER-2 overexpression and triple-negative breast cancer（TNBC）. The correlation of prognosis in different breast cancer molecular subtypes with age， tumor size， lymph node metastasis and clinical stage were analyzed. Results Among 822 cases， 54 cases were found with recurrence or metastasis and 46 cases died with the mortality of 5.6％. The result showed statistical differences among different molecular subtypes of breast cancer regarding the age， tumor size and clinical stage（P＜0.05）, but no statistical difference was observed on the lymph node metastasis（P＞0.05）. Survival analysis showed that factors affecting the prognosis were age， clinical stage， tumor size， lymph node metastasis status and molecular subtypes. Multivariate analysis found that the molecular subtypes and lymph node metastasis status were the independent factors of breast cancer prognosis. The prognosis of HER-2 subtype breast cancer was the worst.
Conclusion Breast cancer molecular subtypes classification has great significance in predicting the prognosis of breast cancer and needs further study to appy to clinical individual treatment of breast cancer patients.