Radiation Therapy for Skin Cancer

Treatment Results for Basal Cell and Squamous Cancer

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radiation field (in blue) surrounding a small squamous cell cancer

Radiotherapy for epithelial skin cancer Locke. International Journal of Radiation Oncology-Biology-Physics, 2001;51:3 : 748-755

The records of 468 patients having 531 lesions were analyzed; 389 basal cell carcinomas and 142 squamous cell carcinomas were treated, 167 of which were recurrent tumors. Median follow-up was 5.8 years. Electron beam irradiation was used in 19%, superficial x-rays in 60%, a combination of electron beam and superficial x-rays in 20%, and megavoltage photons in <2%.

Results : The overall local tumor control rate was 89%; it was 93% for previously untreated lesions and 80% for recurrent lesions. Patients with basal cell carcinoma had a 92% overall control rate; patients with squamous cell carcinoma 80%. Overall, 92% of the treated population with cosmesis data had excellent or good results. The overall complication rate was 5.8%, consisting primarily of soft-tissue necrosis.

Conclusions : Radiotherapy remains an excellent treatment modality for epithelial skin cancer. Local tumor control, cosmesis, and complications are related to the size of the primary lesion. Recurrent lesions fared worse, and therefore treatment at the earliest possible stage is strongly recommended.The use of electron beam irradiation requires additional technical details. Considerations for prescription depth, bolus, and sufficient margin (for penumbra at field edge) are critical. The minimum typical margin ranges from 2 to 3 cm. Small field sizes require even more margin because of changes in the beam profile. The appropriate bolus for 6–12 MV photons is necessary (0.5–1 cm) to ensure a 100% dose at the surface.Our institutional treatment guidelines are as follows. For basal cell carcinoma lesions of <1 cm, 40 Gy is appropriate, and for basal cell carcinoma lesions [le] 3 cm or squamous cell carcinoma <1 cm, we recommend 45–50 Gy. For larger basal cell and squamous cell carcinoma lesions, we recommend 60 Gy. Treatment is given in 2.5-Gy fractions/day, 4 days/wk. see data table below