Adjuvant endocrine therapy in pre- versus postmenopausal patients with steroid hormone receptor-positive breast cancer: results from a large population-based cohort of a cancer registry

Purpose Adjuvant endocrine therapy (ET) is indicated in patients with steroid hormone receptor (HR)-positive breast cancer. The aim of this study was to evaluate the quality of HR determination and adjuvant endocrine treatment of breast cancer patients in a large cohort of more than 7000 women by analyzing data from a population-based regional cancer registry. Methods Data from the Clinical Cancer Registry Regensburg (Bavaria, Germany) were analyzed. Female patients with primary, nonmetastatic invasive breast cancer who were diagnosed between 2000 and 2012 ( n = 7421) were included. HR-status was available in 97.4 % ( n = 7229) of the patients. This data set ( n = 7229) was used for subsequent statistical analyses. Results Since 2009, almost a complete rate of 99.6 % of analyzed HR-status was achieved. In sum, 85.8 % of the patients ( n = 6199) were HR-positive, whereas 14.2 % ( n = 1030) were HR-negative. Overall, 85.3 % ( n = 5285) of HR-positive patients received ET either alone or in combination with chemotherapy (CHT) and/or trastuzumab. The majority of premenopausal patients received CHT plus ET (716 patients, 52.3 %). In postmenopausal patients, the most frequent systemic therapy was ET alone (2670 patients, 55.3 %). Best overall survival (OS) was found in HER2-/HR-positive patients receiving CHT plus ET plus trastuzumab (7-year OS rate of 97.2 % in premenopausal patients versus 86.9 % in postmenopausal patients). Premenopausal patients had a reduced benefit from additional CHT than postmenopausal patients. Premenopausal patients receiving only ET had a 7-year OS rate of 95.3 % compared to 92.7 % of patients receiving CHT plus ET. In contrast, postmenopausal patients treated with CHT plus ET had a 7-year OS rate of 84.0 % in comparison with those patients receiving only ET with a 7-year OS rate of 81.7 %. Conclusions Analysis of HR in patients with early breast cancer achieved a very high quality in recent years. The vast majority of HR-positive patients received ET, and this guideline-adherent use improved OS. Inverse effects of the CHT plus ET combination in premenopausal versus postmenopausal patients and a still existing minority of patients not receiving guideline-adherent treatment should be further investigated in future studies.