[Normal tissue tolerance to external beam radiation therapy: skin]

Area of Science:

• Oncology
• Radiation Oncology
• Dermatology

Background:

• Radiation therapy frequently causes acute and chronic skin toxicities.
• These toxicities can necessitate treatment interruption and result in long-term cosmetic concerns.
• Alopecia (hair loss) is a common, usually reversible, side effect.

Purpose of the Study:

• To review factors influencing skin, hair, and nail toxicities during radiation therapy.
• To discuss the impact of radiation parameters and patient-specific conditions on toxicity.
• To evaluate the risks and benefits of re-irradiation.

Main Methods:

• Review of existing literature on radiation-induced skin toxicity.
• Analysis of patient-related factors (e.g., nutrition, age, smoking, comorbidities).
• Examination of radiation therapy parameters (dose per fraction, total dose, duration, fractionation schedules, irradiated surface area).

Main Results:

• Patient factors like undernutrition, advanced age, obesity, smoking, and pre-existing skin or autoimmune diseases increase toxicity risk.
• Higher doses per fraction and total radiation doses correlate with increased acute and chronic toxicities.
• Dose thresholds for severe skin toxicity are generally above 50 Gy, while permanent alopecia is linked to follicle dose.

Conclusions:

• Skin toxicity is multifactorial, influenced by patient characteristics and radiation delivery techniques.
• Careful evaluation of the benefit-risk ratio is crucial, especially for re-irradiation in head and neck cancers.
• Advanced radiation techniques offer improved methods for sparing the skin and minimizing adverse effects.