Risk of second primary neoplasm and mortality in childhood cancer survivors based on a national registry database

Objective: Although overall childhood cancer survival has improved, survivors may still have an elevated risk for second primary neoplasm (SPN) and excess mortality. The aim of the current study was to estimate the risks for SPN and mortality in childhood cancer survivors in Israel as compared to the general population. Methods: All children aged 0–19 diagnosed with primary neoplasm between 1980–2007 who survived at least 5 years following diagnosis were included in the study. Follow-up continued until December 31st, 2013, or diagnosis of SPN, or death due to any cause (the earliest of these events). Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) were calculated. Cox proportional hazards regression was employed to assess predictors of SPN and mortality. Results: The cohort consisted of 6637 childhood cancer survivors. A total of 244 all-site SPN cases were observed. Compared to the general population, the risks for SPN and for mortality were significantly increased (SIR = 5.48; 95%CI: 4.82–6.22 and SMR = 13.99; 95%CI = 12.54–15.56, respectively). Factors predicting SPN were sex (female), older age at first diagnosis, and initial cancer diagnosis (lymphomas). Factors predicting mortality were older age at first diagnosis, initial cancer diagnosis (myeloproliferative diseases) and earlier years, according to calendar period of initial diagnosis. Conclusions: Although 5-year childhood cancer survival is high, survivors are at elevated risk for SPN and mortality, and the risks are associated with baseline characteristics of the patients. The increased risks should be considered when planning treatment, follow-up and surveillance of the survivors.