Second primary malignancies associated with radiation therapy in cervical cancer patients diagnosed between 1975 and 2011: a population-based competing-risk study

BACKGROUND: Cervical cancer is a major health threat for women. Radiotherapy plays an important role in the treatment of cervical cancer. However, its overall benefit has been questioned due to the risk of second primary malignancies. METHODS: The Surveillance, Epidemiology, and End Results (SEER) database was used to search for cervical cancer patients diagnosed between January 1975 and November 2011. Factors that could possibly affect the occurrence of second primary malignancies included the year of diagnosis, gender, ethnicity, histologic type, SEER cancer stage, histology, grade, and whether surgery, chemotherapy, or radiotherapy were used. Age-adjusted and propensity scoring matching (PSM)—adjusted competing-risk analysis was applied for analysis. RESULTS: Of the 23,112 patients identified through SEER, 14,800 (64.0%) received radiotherapy. Second malignancies were diagnosed in 2,545 (11.0%) cases. PSM-adjusted competing analysis revealed that patients receiving radiotherapy had a significantly higher risk of developing a second cancer in the colon, rectum and anus [hazard ratio (HR): 1.43; 95% confidence interval (CI): 1.09–1.87; P=0.01], lung and bronchus (HR: 1.41; 95% CI: 1.13–1.76; P=0.002), corpus uteri (HR: 3.71; 95% CI: 1.71–8.06; P<0.001), ovary (HR: 2.79; 95% CI: 1.38–5.64; P=0.004), and urinary bladder (HR: 2.18; 95% CI: 1.35–3.54; P=0.002). However, radiotherapy significantly lowered the risk of second cancers in the female breast (HR: 0.67; 95% CI: 0.52–0.86; P=0.002). Age-adjusted competing-risk analysis showed generally consistent results. CONCLUSIONS: Radiotherapy increased the risk of second cancers among cervical cancer patients. Those who underwent radiotherapy had a significantly higher risk of developing a second cancer in the colon, rectum and anus, lung and bronchus, corpus uteri, ovary, and urinary bladder.