Outcome after neoadjuvant chemotherapy in estrogen receptor-positive and progesterone receptor-negative breast cancer patients: a pooled analysis of individual patient data from ten prospectively randomized controlled neoadjuvant trials

The estrogen receptor (ER) is involved in control of progesterone receptor (PgR) expression and lack of PgR may be also a surrogate of altered growth factor signaling. The aim of this study was therefore to investigate PgR expression as predictive factor for response to neoadjuvant therapy and long-term outcome.Five thousand and six hundred and thirteen patients with primary breast cancer and positive ER expression from ten German neoadjuvant trials of anthracycline and taxane-based chemotherapy were included. Pathologic complete response (pCR), disease-free survival (DFS), distant disease-free survival (DDFS), overall survival (OS), and local recurrence-free survival (LRFS) were compared according to PgR expression.The lack of PgR expression (1172 patients) was associated with grade 3 (38.4 vs. 26.3%; p 0.001), nodal involvement (cN2) (6.8% vs. 4.7%; p = 0.004), and HER2 positivity (36.2 vs. 22.3%; p 0.001). pCR rates of PgR-negative tumors were higher in the entire cohort (13.8 vs. 7.5%; p 0.001) and in the HER2-negative subgroup (11.2 vs. 5.8%; p 0.001). In multivariable logistic regression, PgR negativity was an independent predictive factor for pCR overall (OR 1.76; p 0.001) and in the HER2-negative patients (OR 1.99; p 0.001). Patients with PgR-negative disease had significantly worse outcome (p 0.001, respectively). Multivariable Cox regression analysis revealed that PgR was an independent prognostic factor for DFS, OS, DDFS, and LRFS.ER-positive/PgR-negative breast carcinomas are associated with higher response but also worse long-term outcome after neoadjuvant therapy. PgR negativity is an independent predictive factor for pCR after neoadjuvant chemotherapy in ER-positive HER2-negative breast cancer.