The loss of progesterone receptor predicts more aggressive biological features and worse outcomes in estrogen receptor-positive and HER2-negative inflammatory breast cancer

AbstractObjective The loss of progesterone receptor (PR) often predicts worse biological behavior and prognosis in estrogen receptor-positive (ER+) breast cancer. However, the impact of PR status on inflammatory breast cancer (IBC) has not been studied for its’ relative low incidence. Therefore, the purpose of our study was to investigate the influence of PR on IBC. Methods Patients with ER + and HER2-negative IBC were selected from the Surveillance, Epidemiology and End Results database. Pearson’s χ2 test was used to compare the clinicopathological characteristics between patients with estrogen receptor-positive/progesterone receptor-positive (ER+/PR+) and patients with estrogen receptor-positive/progesterone receptor-negative (ER+/PR-). Univariate and multivariate analyses were performed to investigate the effects of PR status on the breast cancer-specific survival (BCSS) and overall survival (OS) in IBC. Results Overall, 1553 patients including 1157 (74.5%) patients with ER+/PR + and 396 (25.5%) patients with ER+/PR- were analyzed in our study. The patients with ER+/PR- were more likely to be high histological grade (p < 0.001) and liver metastasis (p = 0.045) compared with patients with ER+/PR+. Despite higher chance of receiving chemotherapy (83.6% vs 77.3%, P = 0.008), patients with ER+/PR- showed worse BCSS (5-year BCSS rate, 34.3% vs 51.3%, P < 0.001) and OS (5-year OS rate, 31.3% vs 46.1%, P < 0.001) compared with ER+/PR + phenotype. Multivariate survival analysis showed that patients with ER+/PR- still had worse BCSS (HR:1.764, 95%CI: 1.476–2.109, P < 0.001) and OS (HR:1.67, 95%CI: 1.411–1.975, P < 0.001) than ER+/PR + phenotype. Furthermore, patients with ER+/PR- showed worse outcomes than ER+/PR + phenotype in most subgroups, especially in patients with younger age (≤ 60 years), lower histological grade, lymph node involved and distant metastasis. Conclusions Patients with ER+/PR- had more aggressive biological behaviors and worse outcomes than patients with ER+/PR + in IBC. Stronger treatments maybe needed for IBC patients with ER+/PR-.