Ó³»­´«Ã½

AIM: Improved survival after childhood cancer has led to a growing population at risk of second malignant neoplasms (SMNs). This study assessed SMN risk and time trends among childhood cancer survivors in Finland.METHODS: Data from the Finnish Cancer Registry included 10 941 patients diagnosed with cancer before age 20 between 1970 and 2020. Patients were followed until 2021 for SMN occurrence (mean follow-up 14.5 years). Standardised incidence ratios (SIRs) and absolute excess risks (AERs) were calculated. Trends were examined by comparing two diagnostic eras: 1970-1990 and 1991-2020.RESULTS: Among 10 941 patients, 498 (4.6%) developed an SMN. The overall SIR was 4.41 (95% CI 4.03-4.81). Patients diagnosed before age 10 had a significantly higher SMN risk (SIR 6.79, 95% CI 5.92-7.76) than those diagnosed at older ages (SIR 3.47, 95% CI 3.07-3.90; p < 0.001). Survivors of central nervous system (CNS) and solid tumours diagnosed in 1991-2020 had more than twice the SMN risk compared with those diagnosed in 1970-1990.CONCLUSIONS: SMN risk remains significant for childhood cancer survivors, particularly for CNS and solid tumour cases, highlighting the need for tailored surveillance and further research on the strategies to mitigate long-term adverse outcomes.