Second Cancers After Uterine Cervical Cancer Treated With Radiation Therapy.

5028 Background: Characterization of second cancer risk after radiation therapy is important in terms of patient management and enabling clinicians to choose the optimal treatment. Methods: We analyzed 2167 patients who had been treated with radiation therapy for uterine cervical cancer between 1961 and 1986. Relative risks (RRs) of second cancer were calculated by using the disease expectancy table provided by the Center for Adult Disease in Osaka. Results: The total number of person-years follow-up was 25771 and 60 patients were lost to follow-up. Two hundred and three patients developed second cancer after radiation therapy, which represents a significant increase in risk compared with a comparable normal population (RR=1.19, 95%CI=1.03–1.37). The estimated cumulative probability for development of a second cancer was 10.9% at 15 yeas and 19.8% at 25 years. The risk was significantly elevated for uterine corpus (RR=6.6, 95%CI=3.10–13.53), lung (RR=1.65, 95%CI=1.07–2.47), and leukemia (RR=3.11, 95%CI=1.35–6.88). Of the 1364 patients who survived longer than or equal to 5 years, 40 developed second cancer in the irradiated field. The estimated cumulative probability for development of a second cancer was 2.38% at 15 yeas and 4.77% at 25 years. In patients who developed second cancer in the irradiated field, the 5-year overall survival rate was 11.2% and the median survival time was 6 months, indicating the poor prognosis. Conclusions: Significantly increased risk of second cancers after radiation therapy for cervical cancer was observed and the cumulative probability of developing second cancers has increased with longer follow-up. No significant financial relationships to disclose.