Radiotherapy—A Renaissance for Skin Cancer

Radiation therapy has undergone unprecedented advances over the past four decades, both in the understanding of radiobiologic effects and in the technical features of external beam delivery. The extent and scope of these changes have largely remained unappreciated outside the specialty of radiation oncology. The net effect of these advances has been improved dosimetry whereby radiotherapy can more evenly target a planned tissue volume while sparing normal tissues. The term dosimetry describes the evenness (homogeneity) and sharpness (conformality) of photon irradiation. Improved efficacy and safety are now reliably deliverable, prompting a need for a general re-appraisal of the place of modern radiotherapy across the spectrum of skin cancer management. Improved techniques are now widely available for the treatment of high-risk or extensive skin cancers, multiple in-field tumours and severe skin field cancerization. Specialised techniques in development include the use of extended radiation field techniques for micrometastatic disease in lymphatic corridors and harnessing the immune stimulatory potential of radiotherapy, especially in conjunction with immunotherapy and targeted therapies. This review aims to provide a summary of these changes for the non-radiation oncologist. The major advances in radiotherapy most relevant to skin cancer will be discussed along with the evidence for several emerging new applications in cancer management.