Objectives: To determine if the likelihood of bilateral primary ovarian tumors differs by histologic subtype.
Methods: Using data collected by the Surveillance Epidemiology and End Results (SEER) program, the analysis included 22,328 women 25-84 years of age who were diagnosed with a borderline or malignant epithelial ovarian tumor during 1992-2000, categorized as to laterality and histologic subtype.
Results: Malignant serous tumors were bilateral in 57.5% of cases. Corresponding figures for mucinous, clear cell, endometrioid and other epithelial tumors were 21.3%, 13.3%, 26.8%, and 35.6%, respectively. Borderline serous tumors were bilateral in 29.8% of the cases compared to only 7.0% of mucinous tumors. The tendency for serous tumors to present as bilateral was consistent across all categories of race, age, and stage.
Conclusions: Serous tumors of the ovary are more commonly bilateral than ovarian tumors of other histologic subtypes. The reasons for this tendency remain to be determined.