SHORT VERSION
Late complications of radiation therapy appear between 3 months and up to 3 years after the treatment end and they are irreversible. The occurrence of these complications is very difficult to predict. It is estimated that only 5 to 10% of all patients undergoing radiotherapy will develop late complications.
Late toxicities of radiation therapy usually occur between 3 months and 3 years after the treatment end. These side effects are rare and unpredictable, although radiation oncologists always think about preventing them when preparing the initial treatment plan by respecting the constraints for the doses delivered to the organs at risk. Unlike acute side effects, their management is often complicated and the outcome uncertain.
The most common late toxicities are caused by tissue retraction, called fibrosis, linked to a vascularization problem. If occurring at the skin level, this results in skin hardening and sometimes pain. In lungs, fibrosis impairs ventilation of the affected segment with possible repercussions on the patient’s respiratory capacity. In bladder (radiation cystitis), fibrosis can lead to urination problems and the presence of blood in urine. In the digestive system, it can lead to digestive disorders and sometimes intestine obstruction or presence of blood in stool in the case of radial proctitis.
Necrosis (i.e. tissue destruction) is another late toxicity, particularly in brain (where it is often difficult to discriminate between radiation necrosis and brain tumor progression) and jaw (in patients with ENT cancer: osteoradionecrosis).
