Ovarian sex cord-stromal cell tumors (SCSTs) are a rare group of ovarian neoplasms that include both benign and malignant diseases. Previous studies found an increased risk of breast, endometrial and ovarian cancers among women with SCSTs. However, the risk of new primary non-sex hormone-sensitive cancers remains underreported. In this study we investigated the incidence of SCSTs and the associated risks of non-sex hormone-sensitive cancers using a nested nationwide cohort in Denmark.

Cases were identified in the Danish National Pathology Registry and matched on birth year to a control cohort of ten women without SCSTs per case using the Danish National Patient Registry. Cancer incidence was determined using the Danish Cancer Registry. Cox proportional hazards regression assessed associations, adjusting for Charlson Comorbidity Index and socioeconomic variables.

A total of 1,387 women with SCSTs were included, with thecomas (66%) and adult granulosa cell tumors (26%) being the most common subtypes. There was an overall increased rate of new primary malignancy (excluding breast, endometrial and ovarian cancers) among women with SCST (HR = 1.36, 95% CI: 1.16-1.6). Increased rates of malignant melanoma (HR = 1.52, 95% CI: 1.14-2.03) and lung cancer (HR = 1.2, 95% CI: 1.01-1.42) were observed in women with thecomas, whereas other SCST subtypes showed no significant associations with risk of new primary cancers.

Overall women with SCSTs have a slightly increased rates of non-hormone-sensitive malignancies, whereas women with thecomas showed marginally elevated rates of lung cancer and melanoma.