Clinical study of first-line endocrine therapy for type ER+/PR+ and ER+/PR− advanced breast cancer

BACKGROUND This study was designed to evaluate the relationship between estrogen receptor (ER) and progesterone receptor (PR) expression status and clinical outcomes in advanced breast cancer patients undergoing first-line endocrine therapy. METHODS Data from 225 advanced breast cancer patients admitted to Henan Cancer Hospital from February 2010 to October 2019 were collected and compared using Chi-squared tests, with Cox regression models being used to identify relevant prognostic factors in these patients. RESULTS PR+ and PR- patients had significantly different median progression-free survival (PFS) times of 25 months (95% CI: 13.50-36.50) and 7 months (95% CI: 4.03-9.97), respectively (P<0.001). Clinical benefit rates (CBR) were also significantly different between these 2 groups (80.9% and 55.6%, respectively; P<0.001). A subgroup analysis of PR+ and PR- patients that underwent aromatase inhibitor (AI) treatment revealed a median PFS of 25.0 months (95% CI: 14.28-35.72) and 7 months (95% CI: 4.18-9.82), respectively (P<0.001), and CBR values of 81.3% and 54.5%, respectively (P<0.001). In addition, for both the whole cohort and the AI subgroup, the total survival of patients with ER+/PR+ breast cancer was longer than that of patients with ER+/PR- breast cancer, and the difference was statistically significant (P<0.001). CONCLUSIONS ER+/PR+ advanced breast cancer patients had a better prognosis than ER+/PR- advanced breast cancer patients undergoing first-line endocrine therapy. In addition, we found that PR status was an independent predictor of first-line endocrine therapy responses in hormone receptor-positive HER2 negative patients.