Parity, menopausal hormone therapy, and risk of ovarian granulosa cell tumor - A population-based case-control study.

Objective: Adult-type ovarian granulosa cell tumors (AGCTs) are hormonally active neoplasms with limited epidemiological data available. We evaluated the effect of parity and postmenopausal hormone therapy (HT) use on the risk of AGCT in a population-based case-control setting.

Methods: We identified all women diagnosed with AGCT during 1994-2015 (n = 505) from the Finnish Cancer Registry. For each case, five controls matched for age were selected from the National Population Registry, which also provided data on parity and ages at deliveries. Information on postmenopausal HT by different regimens (estradiol-only, sequential estrogen-progestin and continuous estrogen-progestin) was obtained from nationwide Prescription Register. The association between parity, ages at deliveries, HT use, and AGCT incidence was evaluated by odds ratios (ORs) using a conditional logistic regression model and stratified by age at index date (<55 years or ≥ 55 years).

Results: Parity and age at first or last delivery had no significant effect on AGCT risk. Systemic postmenopausal HT had been used by 20.4% of women who were later diagnosed with AGCT. The risk for subsequent AGCT was significantly decreased among users of estradiol-only therapy for at least five years (OR 0.28; 95% confidence interval 0.08-0.94) and continuous estradiol-progestin therapy for 6 months to 5 years (0.23; 0.08-0.71).

Conclusions: Unlike in epithelial ovarian cancer, AGCT development is not clearly associated with parity, and users of postmenopausal HT do not seem to carry an excess risk for AGCT formation.