Implications of Progesterone Receptor Status for the Biology and Prognosis of Breast Cancers

Abstract

Background: It remains unknown whether knowledge of the status of progesterone receptor (PR) expression is useful for distinguishing between luminal A and B breast cancer subtypes and for providing an accurate prognosis for patients with estrogen receptor-positive (ER+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer. We aimed to assess the role of PR status in determining the biology and prognosis of early ER+ and HER2- breast cancer. Methods: This was a retrospective study of 105 patients with ER+ and HER2- breast cancer who underwent surgery between 2005 and 2013. Relapse-free survival (RFS), distant-metastasis-free survival (DFS) and overall survival (OS) were evaluated. The prognostic value of PR was evaluated using a Cox regression model. Results: Apart from the menstruation status, there were no significant differences between the PR+ and PR- patients. PR- patients exhibited a tendency towards a higher nuclear grade and Ki-67 labeling index. In particular, postmenopausal patients with PR expression status < 10% exhibited a significantly higher nuclear grade and tendency towards a higher Ki-67 labeling index. After a median follow-up of about 5 years, the 5-year RFS, DFS and OS rates of the PR+ and PR- patients were not significantly different. PR was not a significant prognostic factor by multivariate analysis. Conclusion: PR status does not have prognostic value for patients with early ER+ and HER2- breast cancer who received adequate therapies. However, it may be reasonable to use PR status for distinguishing between luminal A and B breast cancer subtypes.