Evaluation of progesterone receptors with different cutoff values according to menopausal status in hormone-positive early breast cancer

The impact of progesterone receptor (PR) expression level on breast cancer prognosis in relation to menopausal status is unclear. This study evaluated the impact of the association between PR expression level and menopausal status on prognosis in patients with estrogen receptor (ER)-positive (> 10%)/human epidermal growth factor receptor 2 (HER2)-negative breast cancer. We retrospectively identified 2,796 patients with ER-positive/HER2-negative early breast cancer and classified them into three groups based on PR expression levels: PR-high (> 10%), PR-low (1-10%), and PR-zero (< 1%). We compared the cumulative incidence of any recurrence (AR) and distant recurrence (DR) among the three groups by menopausal status. Over a median follow-up of 84.5 months, there were 324 AR and 264 DR events. In premenopausal patients, the PR-zero group (1,155 patients) had a significantly worse prognosis than did the PR-low (44 patients) and PR-high (60 patients) groups. Meanwhile, postmenopausal patients in the PR-zero (219 patients) and PR-low (167 patients) groups had similar prognosis, both significantly worse than the PR-high group (1,151 patients). Varying cutoff values of PR expression according to menopausal status could help determine more personalized treatment strategies.