Second Primary Cancer After Bladder Cancer: A Comprehensive Analysis of a National Cancer Registry

Bladder cancer (BC) is one of the most common cancers and many patients will experience long-term survival. Non-urothelial second primary cancers (SPC) relatively frequently occur in the population of BC survivors.

Czech National Cancer Registry was the principal data source for this study. The risk of development of non-urothelial SPC after BC was assessed by the standardized incidence ratio (SIR). The standardized mortality ratio (SMR) was utilized to determine the risk of death from SPC following BC.

Of the total of 61,314 patients with BC, a cohort of 12,645 survivors diagnosed with a SPC were analyzed. Compared to the general population, the SIR of neoplasia was significantly increased in BC survivors, with a SIR of 1.75 (95% confidence interval [CI] 1.72-1.78) for all cancers, especially during the first 5 years after BC diagnosis. The SMR was increased in BC survivors (1.25; 95% CI 1.21-1.29) for all cancers. Lung cancer frequently occurred as a SPC and was associated with high mortality in BC survivors. BC survivors also had a higher risk of laryngeal cancer and other cancers known to be strongly associated with smoking, but also of soft tissue tumors, colorectal cancer, chronic lymphocytic leukemia, and thyroid cancer.

The present large registry-based study shows that BC survivors have a significantly higher risk of being diagnosed with another primary cancer compared to the general population, especially during the first 5 years after BC diagnosis. In addition to smoking-related cancers, increased incidence of some cancers not known to be associated with smoking was observed.