Because they also damage healthy cells, radiation therapy or chemotherapy can result in a new cancer, often many years after paediatric cancer. These second cancers are different from late relapses, which, although they are rare, can also occur several years after treatment.
Overall, less than 10% of adults treated for paediatric cancer have a second cancer within the 30 years following the first treatment. However, the risk increases after this period.
These cancers can occur in the breast, thyroid, brain, bones or, more rarely, elsewhere.
The risk of second cancer is increased by several risk factors:
– Female sex;
– Young age at diagnosis;
– Radiotherapy, especially near the neck (risk of thyroid cancer), or the thorax (risk of breast cancer).
– Patients who received anthracycline agents or epipodophyllotoxin agents; patients who received high doses of alkylating agents. The doses used for these chemotherapies have been decreased over time (referred to as “therapeutic de-escalation”), limiting these harmful effects.
Some survivors had leukaemia as a second cancer. It occurred mostly within the 10 years following childhood cancer, when significant doses of alkylating agents, anthracyclines or epipodophyllotoxins had been administered. Over recent decades, the doses of these treatments have been regularly reduced, limiting the harmful effects associated with these chemotherapies.
More rarely, some people have a genetic predisposition to develop cancer, which can be suspected in cases of cancer that also occur in other members of the family at a young age. Thus, analysis of the family history can help to assess the risk. This is a rare situation, but if that is the case, your GP may refer you for a specialised genetic consultation during which the opportunity to undertake specific genetic research will be discussed.
Results of the study FCCSS on the risk of second tumour: Publications