ObjectiveTo explore the expression of programmed cell death 4 (PDCD4) in different subtype of breast cancer and its relationship to prognosis. MethodsThree hundred and thirty-eight patients with breast cancer from January 2007 to December 2009 in this hospital were collected. All these patients were categorized into three subtypes which was luminal, HER-2 positive, and triple negative according to the results of immunohistochemical stain. SP immunohistochemistry was used to detect the expression of PDCD4 in the different subtype of breast cancer. Kaplan-Meier and Cox proportional hazards model was used to analyze the prognosis. Results①The positive rate of PDCD4 expression was 73.37%(146/199), 30.16%(19/63), and 35.53%(27/76) in the luminal, HER-2 positive, and triple negative breast cancer, respectively. The expression of PDCD4 was downregulated especially in the HER-2 positive and triple negative breast cancer(χ2=38.315, P=0.000; χ2=33.746, P=0.000) as compared with the luminal breast cancer. 2 The disease free survival and overall survival rates in the PDCD4 positive patients were significantly higher than those in the PDCD4 negative patients(P < 0.05) despite the subtypes.③Cox model revealed that T staging, N staging, and PDCD4 were the independent prognostic factors for disease free survival and that histological grade, T staging, N staging, and PDCD4 were the independent prognostic factors for overall survival. ConclusionsPDCD4 expression is downregulated in all subtypes of breast cancer especially in HER-2 positive and triple negative breast cancer, and the loss of PDCD4 expression is correlated to poor prognosis. PDCD4 is an independent prognostic factor of breast cancer.