Risk of secondary primary malignancies in survivors of upper tract urothelial carcinoma: A nationwide population-based analysis.

BACKGROUND: To investigate the cancer types and risk factors of secondary primary malignancy (SPM) in patients with upper tract urothelial carcinoma (UTUC) in Taiwan.

METHODS: Using National Health Insurance Research Dataset and catastrophic illness registry, we enrolled newly diagnosed UTUC patients from 2000 to 2013. Those without catastrophic illness registration were excluded from the study. The cancer types and hazard ratios (HRs) of subsequent SPMs were calculated according to the antecedent malignancy. We analyzed the risk factors for developing SPMs using multivariate Cox proportional hazard models.

RESULTS: A total of 9050 UTUC patients were registered and 2187 (24.2%) patients developed SPMs during the study period. As compared with primary UTUC, the relative risk ratios of SPM was 2.5 folds and 18% higher in those with antecedent non-UC malignancy and with bladder cancer history, respectively. Totally, 387 (37.8%) of 1022 UTUC patients with antecedent non-UC malignancy developed subsequent SPM after UTUC diagnosis. The antecedent and subsequent cancer types are similar and kidney cancer is most common, followed by hepatoma. Multivariate analysis showed that a history of antecedent non-UC malignancy is the most unfavorable factor for SPM development (HR, 2.50; 95% CI, 2.23-2.81), followed by liver disease, male gender, antecedent bladder cancer history, age ≥ 75 years, and chronic kidney disease.

CONCLUSIONS: Our study, conducted in Taiwan and involving 9050 UTUC patients, meticulously examined the types of SPM and the associated risk factors. Our research unearthed several pivotal discoveries: a preceding history of non-UC malignancies emerged as the single most influential factor contributing to the occurrence of subsequent cancers, followed by liver disease, male gender, antecedent bladder cancer history, age ≥75 years, and chronic kidney disease. Futhermore, kidney cancer emerged as the predominant subsequent malignancy, closely trailed by hepatoma..