Synchronous and Metachronous Malignancies After Malignant Struma Ovarii in the SEER Database.

BACKGROUND/AIM Second primary tumors (SPTs) often occur, either synchronous or metachronous. Struma ovarii is a rare ovarian tumor represented by thyroid tissue in the ovary. Among other factors, production of thyroid hormones by the tumor or a shared genetic predisposition can further influence the development of SPTs. The occurrence of SPT, either synchronous or metachronous, following a long follow-up, has never been considered extensively. PATIENTS AND METHODS We analyzed the Surveillance, Epidemiology, and End Results (SEER) database from 1973 to 2011 to follow-up all the cases of malignant struma ovarii in an effort of calculate the occurrence of SPTs in this cohort of patients. RESULTS We identified 21 patients with malignant struma ovarii in the period between January 1973 and December 2011. In a follow-up period of 219.57 person-years, 3 patients had SPT. One patient had synchronous thyroid sclerosing carcinoma, 1 patient had metachronous papillary adenocarcinoma with a latent time of 7 years and 1 patient had synchronous salivary ductal carcinoma. CONCLUSION Up to date, only thyroid synchronous tumors have been reported in the literature. A synchronous and a metachronous thyroid tumor, plus a synchronous salivary gland tumor, were found. A significant association between malignant struma ovarii and thyroid/salivary gland cancer is herein demonstrated.