Introduction/Background Non-epithelial ovarian cancers are rare but affect women of all ages. The etiology is unknown. Non-epithelial ovarian cancers are divided into two major subgroups: sex cord-stromal tumors (SCSTs) and germ cell tumors (GCTs). Whereas parity is protective for epithelial ovarian cancer, its association with non-epithelial ovarian cancer and its subtypes remains less clear, as are associations with other pregnancy-related factors.
Methodology All parous women with births recorded in the medical birth registries from the Nordic countries with a subsequent diagnosis of SCSTs (n=420) and GCTs (n=345) during 1967–2013 were compared with up to 10 controls (SCSTs n=4041; GCTs n=2942) matched on the cases’ birth year and country. We used conditional logistic regression to estimate odds ratios (ORs)with 95% confidence intervals (CI)of associations of pregnancy-related factors.
Results Number of births was not associated with risk of SCSTs or GCTs. Older age at last birth was inversely associated with the risk of SCSTs (age 30–39 versus <25 years: OR 0.64, 95% CI 0.45–0.90). The risk decreased gradually with increasing age at birth. Shorter time since first or last birth was also inversely associated with SCSTs. None of the investigated factors were associated with GCTs.
Conclusion In this large population-based case-control study among parous women, number of births was not protective for risk of SCSTs and GCTs.The inverse associations with greater age at last birth and shorter time since last birth observed for SCSTs, however, suggest that these subtypes may be influenced by the woman’s reproductive history.
Disclosure Ingrid Glimelius have received Honoraria from Janssen for projects unrelated to the current study.
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