Progesterone receptor loss identifies hormone receptor-positive and HER2-negative breast cancer subgroups at higher risk of relapse: a retrospective cohort study

BACKGROUND To assess the prognostic value of progesterone receptor (PR) expression in patients with hormone receptor-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer subgroups. METHODS A retrospective review of breast cancer patients who underwent mastectomy or breast-conserving surgery between January 1998 and December 2007 was performed. The prognostic impact of PR status on disease-free survival (DFS) was analyzed. RESULTS Of the 1,301 patients included in this study, the median follow-up time was 64 months, and the median age was 46 years. There were 18.4% of patients (n=219) with PR negative (PR-) cancer. Women with PR-breast cancer were more likely to be postmenopausal (P<0.001) and have pN3 stage (P=0.031) and Stage III (P=0.049) cancer. Cox regression univariate and multivariate analysis showed that PR status was a significant prognostic factor for DFS. Patients with PR- status had poorer DFS (hazard ratio =1.626, 95% confidence interval =1.060-2.497, P=0.026). The 5-year DFS for patients with PR- and PR+ breast cancer was 79.4% and 86.2%, respectively, and the 8-year DFS for patients with PR- and PR+ breast cancer was 69.6% and 78.1%, respectively (P=0.012). A significant difference in DFS was observed between PR- and PR+ disease in patients with node-negative cancer, but was not for patients with lymph node metastasis (P=0.242). In premenopausal patients, DFS varied significantly by PR status (P=0.049). A marginally significant difference in DFS between the PR- and PR+ disease was seen in postmenopausal patients (log rank P=0.065). CONCLUSION Lack of PR expression is associated with worse survival in patients with hormone receptor-positive and HER2-negative breast cancer subgroups.