Risk of second primary Cancer among bladder Cancer patients: a population-based cohort study in Korea

BACKGROUND: For the expanding population of bladder cancer survivors in Korea, the development of subsequent cancers is a significant concern. Here, we provide the second primary cancer incidence rates and types in Korean patients with bladder cancer. METHODS: Using population-based data from the Korea Central Cancer Registry from 1993 to 2013, we studied the standardized incidence ratios among 48,875 individuals with an initial diagnosis of bladder cancer. Standardized incidence ratios for second primary cancers were evaluated according to age at diagnosis, latency, diagnostic year, and treatment. RESULTS: Over the same period, the overall risk of a second primary cancer was reduced by 6% in patients with bladder cancer compared with the development of a new malignancy in the general population (standardized incidence ratio = 0.94; 95% CI, 0.91–0.97, p < 0.05). For specific cancers, the standardized incidence ratios for stomach, colon, liver, and non-Hodgkin lymphoma were significantly lower in patients with bladder cancer. However, the risk of prostate and kidney cancer in patients with bladder cancer were significantly increased. The risk of lung squamous cell carcinoma and lung adenocarcinoma as second primary cancers was significantly elevated in patients with bladder cancer. CONCLUSION: Korean patients with bladder cancer have a 6% lower risk of developing a second primary cancer. However, they have a higher risk of developing subsequent prostate and kidney cancers, lung squamous cell carcinoma, and lung adenocarcinoma, suggesting the need for continual intensive cancer surveillance among bladder cancer survivors. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12885-018-4530-3) contains supplementary material, which is available to authorized users.