Trends over time in the incidence and use of hormonal therapy in endometrial cancer: a population-based study in the Netherlands

Introduction According to current guidelines, hormonal therapy may be applied in endometrioid type endometrial cancer as an alternative to surgery for fertility preservation and in medically unfit patients. Since it is unknown how often hormonal therapy is applied, the objective of this study was to investigate trends over time in hormonal therapy use in the background of the overall incidence of endometrial cancer. Methods All patients with endometrial cancer (n=48 222) registered in the Netherlands Cancer Registry in the period 1989-2018 were included. European age-standardized incidence rates with corresponding estimated annual percentage change were calculated to describe trends in the incidence of endometrial cancer. The use of hormonal therapy was analyzed in the three periods 1989-1998, 1999-2008, and 2009-2018 for the following sub-groups: primary and adjuvant therapy, International Federation of Gynecology and Oncology (FIGO) stage I-II and III-IV, and by age group. Results The European age-standardized incidence rate of endometrioid endometrial cancer peaked in 2004 with a significant increase from 1989 to 2004 (annual percentage change 0.55; 95% CI 0.10 to 0.99, p=0.020) and a subsequent decrease from 2005 to 2018 (annual percentage change -1.79; 95% CI -2.28 to -1.31, p<0.001). The incidence rate of non-endometrioid type endometrial cancer increased significantly in the study period. Hormonal therapy was used in 1482 (3.5%) patients with endometrioid endometrial cancer. Among patients with FIGO stage I aged <= 40 years, hormonal therapy increased from 0% in 1989-1998 to 27% in 2009-2018. Primary hormonal treatment increased from 175 patients (5.5%) to 329 patients (7.8%) in those aged >= 75 years. Adjuvant hormonal treatment was mostly used in advanced stage endometrial cancer. Conclusions The use of primary hormonal therapy in endometrioid type endometrial cancer increased over time in patients aged <= 40 years and among elderly patients. The observed trends in the current use of hormonal therapy support the need to study the effect of hormonal treatment in elderly patients and as adjuvant treatment in advanced stage endometrial cancer.