Objective: To estimate the occurrence of synchronous epithelial ovarian and endometrial cancers among ovarian cancer patients and to assess survival of women with synchronous cancers.
Methods: Synchronous ovarian and endometrial cases were identified using data from the Surveillance, Epidemiology, and End Results Program from 1973 to 2005. Multivariable Cox-proportional hazards regression was used to estimate risk of death from ovarian cancer, comparing synchronous ovarian and endometrial cancers with single ovarian cancers and adjusting for demographic, prognostic, and treatment characteristics.
Results: Synchronous cancers represented less than 3% of the 56,986 epithelial ovarian cancer cases, regardless of the time interval between detection of both cancers. Favorable characteristics for synchronous patients included younger age at diagnosis, earlier stage of disease, and better grade of disease. Multivariable adjusted hazard ratios showed a 25% reduction in risk of death from ovarian cancer for synchronous tumors compared with single tumors (hazard ratio 0.75, 95% confidence interval [CI] 0.66-0.85). In stratified analysis by stage, the corresponding hazard ratios for localized and distant stages were 0.63 (95% CI 0.42-0.95) and 0.70 (95% CI 0.60-0.81), respectively.
Conclusion: Women with synchronous ovarian and endometrial cancers exhibit favorable survival outcomes as compared with patients with single ovarian cancers, even after adjusting for demographic, prognostic (including stage), and treatment characteristics. The survival advantage associated with having synchronous cancers persisted after analyses were restricted to distant stage.
Level of evidence: III.