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| Cancer radiotherapy |
Late reactions | |
Sequelae and late reactions typically occur at least six months after completion of irradiation, i.e. when acute reactions have been healed.
Whereas sequelae are unavoidable because inherent to treatment, late complications can be prevented when certain favouring factors can be avoided.
It is both an acute reaction and a late sequela.
It is clinically manifested by xerostomia with difficulties in speaking and to swallowing. Its intensity is correlated to the irradiated volume of the salivary glands. Potential, although usually very partial recovery may be observed after a few years for doses lower than 40 Gy, but this recovery is purely quantitative. Qualitatively, the saliva never recovers its original properties after irradiation (alteration of buffer properties, diminution of anti-bacterial power by diminution of lysozymes and IgA). Hyposialia therefore predisposes to mouth infections and tooth decay.
The symptomatic treatment associates mouth washing with bicarbonate solutions and antiseptics and, if necessary, antifungic agents. The use of chewing-gum may facilitate salivation and the use of artificial saliva and water sprays can improve local comfort. The cessation of alcoholic and tobacco intoxication is essential.
They concern all teeth, be they situated within the irradiated volume or not.
They often begin in the form of decay at the tooth neck, principally for incisors and inferior canine teeth; occasionally, a dentine lesion can be seen with a fracture of the tooth neck or a blackish coloration of the irradiated tooth (ebony teeth)
The pathogenesis of such dental lesions can be the direct result of a radio-induced modification of the micro-circulation of the tooth pulp, or indirectly related to modifications in saliva (as seen above), with an acidification which promotes the development of decay bacteria, the reduction of the fluorine concentration and a diminution of enamel resistance.
The treatment of these tooth alterations is above all preventive. Prior to irradiation, it is essential to;
- restore as healthy a buccal cavity as possible
- extraction of invaded or decayed teeth or teeth with major paradentitis,
- treatment of the teeth which can be conserved and will be secondarily used for prosthetic rehabilitation after treatment,
- tooth scaling,
- temporary ablation of bridges, which constitute supplementary irritation factors during irradiation.
- begin the withdrawal of tobacco and alcohol
- sensitise the patient to the importance of
- the maintenance of good mouth and tooth hygiene by regular brushing and antiseptic mouthwashes,
- daily fluorination to the end of life, by the use of a fluorine gel drip, applied 5 minutes per day. Since fluorine is not swallowed, no secondary fluorosis will occur.
A dental prosthesis will be fitted 8 to 12 month after radiotherapy.
which induces a permanent crop.
Trismus is secondary to irradiation of the temporomandibular articulations and of the masticator muscles. It can be reduced by daily remedial mandible gymnastics.
- Castration among women after 12 Gy, in relation to the great sensitivity of the ovaries, which increases as the patient approaches menopause
- Temporary sterility for men after 5 Gy, definitive after 20 Gy, if the testes are in the irradiated field
- Vaginal dryness
- Impotence caused by the destruction of the pudental nerve
- Lymphoedema of the inferior limbs particularly when irradiation follows a lymphadenectomy
- Stiffness caused by fibrosis of the joint capsule
- Muscle and skin fibrosis
- Skin atrophy and dryness
Radiocancers (such as osteosarcoma, spinal cell carcinoma) arise after an often very long latency period of ten years or more, preferentially in zones bordering the irradiation fields.
However the risk is low, evaluated at less than 1%; the incidence dramatically increases with associated chemotherapy reaching 8 to 10% in patients with Hodgkin’s disease treated by an association of radiotherapy and chemotherapy (the MOPP regimen).
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