Influence Of The Progesterone Receptor On The Prognosis Of Breast Cancer In Interaction With Other Prognostic Factors.

Abstract Introduction: The expression of the estrogen receptor (ER) and/or the progesterone receptor (PR) is a predictive factor for the response to endocrine treatment and to chemotherapy in primary breast cancer. Knowledge about the prognostic relevance of the PR is rare and partly controversial. Aim of this retrospective study was to analyze the prognostic relevance of PR. Methods: Between 1995 and 2008, data from 5,144 patients with heterogeneously treated primary breast cancers have been collected in 3 German university hospitals. The laboratories used immunhistochemical assays for the investigation of the ER and PR. The PR-expression was correlated with patient and tumor characteristics. For each outcome parameter overall survival (OS), distant disease free survival (DDFS) and local recurrence free survival (LRFS) cox proportional hazad models were built. Furthermore the effect of the PR status was analyzed according to tumor subgroups. Results: PR status was associated with a more favourable OS, DDFS and LRFS in the univariate analysis. PR remained an independent prognostic factor for OS and DDFS but not for LRFS in the cox proportional hazard model. For OS and DDFS the prognostic effect of PR seemed to be consistent among the subgroups and was significant for most of them. Comparing subgroups there was a difference between the HR for ER negatives and ER positives. In ER negative tumors the prognostic effect of the PR seemed to be larger (HR=0.40; 95%CI: 0.25−0.63) than in ER positives (HR=0.68; 95%CI: 0.53−0.87). For all other subgroups there seemed to be no interaction between PR status and the other prognostic factors. Conclusion: PR positivity results into a similarly favourable prognosis in ER negative and ER positive patients. ER positivity alone seems not to be sufficient to define a group of patients with the most favourable prognosis. On the contrary, patients with ER positive, PR negative tumors have a signicantly deteriorated prognosis and seem to be a patient group, which should be investigated concerning drug resistance mechanisms. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-02-07.