Association of progesterone receptor status with 21-gene recurrence score and survival among patients with estrogen receptor-positive breast cancer

Progesterone receptor (PR)-negative tumors have been shown to have worse prognosis and were underrepresented in recent trials on patients with estrogen receptor (ER)-positive breast cancer. The role of PR-nega‑ tive status in the context of 21-gene recurrence score (RS) and nodal staging remains unclear.