Single fraction radiotherapy for small superficial carcinoma of the skin

Aims: To define the optimal dose and maximum tumour size of basal and squamous cell carcinoma of skin that can be treated by single fraction radiotherapy. Materials and methods: A review was undertaken of 1005 lesions of basal/squamous cell carcinoma of the skin involving 806 patients treated at a single centre with 10 years of follow-up. Doses of 18, 20 and 22.5 Gy were used. The recurrence and necrosis free survival rates for different anatomical sites and radiation doses were calculated. Results: The overall disease-free and necrosis-free rates at 5 years were 90% and 84%, respectively. The crude 10-year recurrence rate was 4% (95% CI 3.4-5.4%), with late skin-necrosis at 6% (95% CI 4.8-7.2%). There was no difference in tumour recurrence rates between 20 and 22.5 Gy (P = 0.3), but there was a significantly higher skin necrosis rate at the treated site in the patients who had received 22.5 Gy (P = 0.003). Most skin necrosis heated spontaneously, with only 16% requiring surgical intervention. Tumours involving the inner canthus had a significantly higher recurrence rate than those involving other areas of the head and neck. Conclusions: Single fraction radiotherapy is an acceptable treatment, for small superficial BCC and SCC of the head and neck region in patients who have difficulty attending multiple hospital visits as long as the field size required for treatment is no larger than 3 cm in diameter. The optimal applied dose for such a lesion on a flat surface is 20 Gy.