OBJECTIVE: To investigate time trends in the incidence of overall, type 1 and type 2 endometrial cancer in Denmark 1978-2014, correcting for hysterectomy.

METHODS: Based on the Danish Cancer Registry and the Danish National Patient Registry we calculated hysterectomy-corrected incidence rates of overall, type 1 and type 2 endometrial cancer. Separate analyses for women <55years (defined as pre- and perimenopausal age) and women aged ≥55years (defined as postmenopausal age) and analyses allowing for different time trends before and after the study period midyear 1996 were performed. Log-linear Poisson models were used to estimate annual percentage change (APC) in incidence with 95% confidence intervals (CI).

RESULTS: The overall incidence of endometrial cancer decreased slightly from 1978 to 1995, but in the last two decades of the study period the incidence has been stable (APC=0.16; 95% CI: -0.19; 0.50). In the study period (1978-2014) type 1 endometrial cancer incidence decreased slightly (APC=-0.67; 95% CI:-0.83; -0.52), whereas the incidence of type 2 endometrial cancer increased substantially (APC=4.85; 95% CI: 4.47; 5.23). The decrease in type 1 endometrial cancer was most pronounced before 1996 in women younger than 55 years (APC=-2.79; 95% CI: -3.65; -1.91), while the largest increase in type 2 endometrial cancer was observed after 1996 (APC=6.42; 95% CI: 5.72; 7.12).

CONCLUSIONS: Over a period of more than 35 years, the incidence of type 1 endometrial cancer decreased, mainly in pre- and perimenopausal women, while type 2 endometrial cancer incidence increased.