Introduction: Childhood cancer survivors are known to be at increased risk for second malignancies.
Patients and methods: The risk of second malignancies was assessed in 1368 5-year survivors of childhood cancer treated in the Emma Children's Hospital AMC in Amsterdam. The median follow-up time was 16.8 years.
Results: Sixty two malignancies were observed against 5.4 expected, yielding a standardised incidence ratio (SIR) of 11.2 (95% confidence interval: 8.53-14.4; absolute excess risk: 3.2 per 1000 person-years). New observations were the strongly increased risks of meningiomas (SIR=40) and basal cell carcinomas (SIR=9). Patients whose treatment involved radiotherapy had a 2-fold increased second cancer risk compared to patients with chemotherapy alone.
Discussion: The relative risk of second malignancies does not decrease till at least 30 years of follow-up. With aging of the survivor cohort this results in a strong increase of the AER, due to the rising background risk of cancer with age.