Treatment of childhood cancers: late effects

In France, about 1 in 1000 young adults aged 20 to 30 years is a survivor of childhood cancer and is thus faced with late effects of their cancer and its treatment (radiation therapy and/or chemotherapy). What are the late effects of childhood cancer therapy? A systematic review by the Scottish Intercollegiate Guidelines Network (SIGN) provides useful information based on European and North American data. Cancer treatments can have many long-term consequences that depend on the drugs and doses used, radiation therapy protocols and irradiated organs, and age at the time of treatment. Cytotoxic drugs and radiation can both cause infertility. Abdominopelvic radiation therapy in girls has been linked to an increased risk of premature delivery and other complications of pregnancy. No increase in birth defects has been reported among children born to childhood cancer survivors. Anthracyclines and radiation therapy can cause cardiomyopathy. Neck irradiation can lead to thyroid disorders, and cranial irradiation to growth retardation. Chemotherapy can cause osteonecrosis and loss of bone density, but without an increased risk of fracture. The risk of cognitive impairment and structural abnormalities of the brain is higher when the child is younger or receives a high cumulative dose of cranial irradiation or total irradiation dosage. Some cytotoxic drugs can damage the kidneys. Cranial radiation therapy can cause long-term neuroendocrine disorders and growth disorders, especially when the dose exceeds 18 Gy. Cytotoxic drugs (alkylating agents, etoposide, etc.) and radiation therapy can cause second cancers of a different histological type. One analysis of second cancers showed a median time to onset of 7 years for solid tumours and 2.5 years for lymphoma and leukaemia. Better knowledge of the late effects of childhood cancer therapy can help orient the choice of treatment towards less harmful options or, if necessary, implement measures aimed at preventing late adverse effects. Childhood cancer survivors must be monitored into adulthood in order to detect such effects.