Thyroid Cancer Benefits the Prognosis of Ovarian Cancer: A SEER-Based Study

IntroductionTo explore the effect of a second thyroid cancer (TC) on ovarian cancer (OC) patient survival, we compared OC patients with or without a second primary TC using data from the Surveillance, Epidemiology, and End Results (SEER) database.MethodsData for OC only, female TC only and OC patients with a second TC (OC2TC) from two periods, 2000-2014 and 1980-1994, were extracted from the SEER database. Differences in clinicopathological and treatment characteristics were analysed using the chi-square test. Cox regression analyses were used to identify risk factors associated with OC survival. Disease-specific survival (DSS) and overall survival (OS) curves were compared using the log-rank test.ResultsThere were 109 OC2TC patients from 2000 to 2014, and significant differences (P<0.001) in the mean age at OC diagnosis, TNM stage and surgical history were found between OC and OC2TC patients. Several factors, including age, grade, TNM stage, histological type and surgical history, influenced OC survival (P<0.001). OC2TC patients showed better survival than OC patients from 2000 to 2014, regardless of age, TNM stage or surgical history. However, this superiority was not significant in cases from 1980 to 1994 (P=0.222 for OS).ConclusionSurvival was better with OC2TC than with OC from 2000 to 2014 rather than 1980-1994, suggesting that TC improved the survival of OC patients from 2000 to 2014.