Radiobiological learnings from unique cases of VMAT in ESFC
Patients with extended skin field cancerisation (ESFC) can have poor oncological outcomes and poor quality of life. The durability of traditional non-surgical skin field treatments is disappointing. Our national radiation oncology teams developed a technique using volumetric modulated arc therapy (VMAT) to treat ESFC which has been published. This technique was influenced by what we learned from unique patient cases, some of which are described herein. Several issues have been uncovered through our experience in treating ESFC to date: the difficulty in measuring acute skin toxicity with the current grading systems; the cause and treatment of pain during the treatment course; optimal total dose and fractionation schedules with VMAT, including the need for a treatment break; radio sensitivity of ESFC; the apparent lack of accelerated repopulation in ESFC; the impact of pre-existing immune-suppression and radiation sensitizing medications; and the need for the “spare strip”–the provision of spare strips of skin on limbs, especially the legs, to preserve lymphatic drainage. Monitoring of the success of the technique is ongoing. The technique also continues to be influenced by unique learning cases as they arise.