Most commonly, treatment reactions begin approximately two weeks after the onset of treatment, peak 7 to 10 days after the final treatment fraction and begin to diminish between 4 to 6 weeks after the treatment has finished. During this acute phase, nursing care may be required.
The skin reactions can be classified into three different types:
- Erythema; this is an inflammatory response to cell death in the epidermis as a result of the radiation and is characterised by the skin becoming red, hot and itchy – similar to sunburn.
- Dry Desquamation; this type of skin reaction occurs due to premature keratinisation of the epidermis where repopulation of the cells damaged by radiation is less than the number of cells which are destroyed. This is characterised by the skin becoming dry, tender and itchy with flaking of the superficial layers .
- Moist Desquamation; this is the most severe type of skin reaction and occurs due to insufficient new cell proliferation of the epithelial layer, leading to the exposure of the deeper dermal layer. This is characterised by painful, blistered skin and the production of sebaceous fluid .
Often during treatment, lesions will develop a scab which repeatedly forms, falls off and re grows. This usually occurs several times until healing is complete and can continue for several weeks following the end of treatment.
In addition to the skin reactions described above, patients who are receiving treatment to mucosal linings, such as nasal or mouth area, may experience an adverse reaction in the lining which is characterised by acute inflammation or ulceration of the mucosal membrane .
Following treatment there are several possible late effects which may occur to the skin of the treated area:
- Pigmentation; a slight permanent change in skin colouring.
- Skin atrophy; thinning of the top two layers of skin, the dermis and epidermis, often causing a depression in the skin.
- Heightened photosensitivity; increased sensitivity to the sun.
- Telangiectasia; dilation of thin walled blood vessels, close to the surface of the skin.
- Necrosis; this rarely occurs although in certain cases tissue necrosis can be seen as a result of damage to the blood vessels.
- Permanent alopecia; hair loss in treatment area.
- Dacryostenosis; lacrimal duct damage after treatment to inner canthus.