Radiotherapy and the skin Flashcards
What are the range of acute skin reactions caused by radiotherapy?
- mild erytherma to confluent moist desquamation and occasionally ulceration
Why are radiation skin reactions not “burns”?
they occur as a result of damage to the basal cell layer of the skin causing an imbalance between the normal production of cells in the basal cell layer and the destruction of cells at the skin surface
What does radiobiological damage affect?
affects regeneration of the skin by the process of repair, redistribution, repopulation and reoxygenation
The damaged cells are replaced by cells moving from resting phase into the active cycle
When does skin damage occur?
rate of repopulation of the basal cell layer cannot match the rate of cell destruction by treatment - an inflammatory response is activated which.is a normal physiological reaction to radiotherapy
- normally takes 10-14 days
Initially the skin will be warm and reddened (erytherma) and it can sometimes become itchy
Once skin gets damaged further, what compensation mechanisms occur?
increasing mitotic activity to try to replace the damaged cells - if news cells reproduce faster than the shedding of the old cells the skin will become dry and flaky (dry desquamation)
As radiotherapy continues what happens?
basal cell layer cannot produce enough new cells to replace the old ones and therefore the outer layer of the epidermis will break down, oedematous with exudate (moist desquamation)- exudate is rich in nutrients to help new growth of new skin cells
Is skin necrosis common?
rarely seen primarily due to the advanced techniques used to deliver radiotherapy
Why does the severity of skin reactions increase 7-10 days after the radiotherapy has completed?
It can take this amount for the cells that have bee affected by radiotherapy to reach the outer epidermis = often the peak when the side effects ca be worse
Following this the side effects will lessen
What is the skin like 4-6 weeks after treatment?
Skin should be healing well, may even be fully healed but there may be some hyper pigmentation (darker)
What is the radiotherapy cycle?
1) radiotherapy activates inflammatory response
2) 10-14 days from 1st treatment - damaged basal cells migrate to skin surface-erythema develops
3) further skin damage - new cells reproduce before old dead cells shed= dry desquamation
4) No new cells to replace dead cells = moist desquamation
5) treatment completed - 10-21 days for basal cells to recover and new skin to grow
What are the intrinsic predisposing factors for radiotherapy induced skin reactions?
Age: natural ageing affects epidermal skin cell cycle causing increased healing time
Nutrition: need good nutrition for adequate skin repair - if it is undernourished there is a greater risk of increased damage
Smoking and alcohol: can decrease capillary blood flow and oxygen levels therefore increasing severity of the skin reaction and reducing healing and ability to fight infection
Co-morbidities: other illnesses and some medications can increase risk and impact on healing e.g. steroids, diabetes
UV exposure: long-term UV exposure increases severity of radiation induced skin reaction and impairs healing
Obesity: extra adipose tissue can compromise healing and exacerbate skin toxicity due to extra skin folds
Infection: presence of bacterial and / or fungal infection can damage the cells in the basal cell layer = delayed healing
What are the extrinsic predisposing factors for radiotherapy induced skin reactions?
Radiotherapy: higher doses and larger areas increase risk
Energy of radiotherapy: higher energy- lesser the skin reaction
Radiosensitisers
Chemical / thermal and mechanical irritants
What is the RTOG 0 grading of skin and what treatment is provided?
No visible skin changes - promote hydrated skin and maintain integrity
What is the RTOG 1 grading of skin and what treatment is provided?
Faint or dull erytherma
Mild tightness of skin and itching may occur
Promote hydrated skin, patient comfort and maintain skin integrity. Treat itchy skin, reduce pain, soreness and discomfort
What is the RTOG 2 grading of skin and what treatment is provided?
Bright erytherma / dry desquamation - sore, itchy and tight skin
Treat the same as RTOG 1
