Superficial HDR brachytherapy for skin lesions involving the finger - The Christie experience

Abstract

Purpose or Objective The standard of care for treatment of skin cancer and refractory precancerous conditions located on the finger is largely surgical management. Surgery usually involves digits/finger amputation or wide local excision with reconstruction. Many patients are elderly and/or frail. Non-invasive methods of treatment are often the preferred option due to favourable cosmetic and/or functional outcomes and improved patient compliance. External beam radiotherapy in finger location is challenging due to depth-dose characteristics in curved surfaces and close target location to joints and bones. HDR brachytherapy (BT) is a well-established non-invasive alternative treatment option delivering high radiation dose to the target with rapid dose fall-off in normal surrounding tissues. We report The Christie experience with HDT BT in the finger location over the past 6 years. Materials and Methods From Jan 2014 to Sept 2020, 13 patients (7 males and 5 females) underwent radical superficial HDR BT to the finger. There were 9 skin SCCs: 5 postoperative and 4 definitive. One patient had BCC and 3 patients had progressive refractory Bowen’s disease. The median age at the time of BT was 71 years (range 52 – 95). The patients were treated with a total dose of 30–34 Gy at 100% isodose in 8 fractions twice a day at least 6 hours apart. Target area was marked out by visual inspection, palpation and high frequency skin ultrasound. All patients were treated with The Christie mould technique: a flap mounted over an individually designed mould composed of a pre-calculated number of layers of thermoplastic material. Patients were followed for at least 2-3 years for treatment toxicity, cosmetic results, and local failures. Acute toxicity was graded using the CTC AE, v. 4.0 and cosmetic outcomes were classified using the RTOG cosmetic rating scale. Results Average follow-up from completion of the treatment was 23.5 months (2-36 months). All patients had an acute reaction to the BT: desquamation, crusting and erythema grade 1 or 2. One patient developed acute grade 3 wet desquamation. All acute toxicity was resolved within 2 months after treatment. Late toxicity was reported in 6 patients: slight/moderate atrophy, pigmentation change and grade 1 or 2 teleangiectasia. No cosmetic or functional results worse than good were observed. 11 patients had no evidence of recurrence in follow-up. 2 patients proceeded to salvage surgery due to either no response to BT or local recurrence at 4 months after BT. 2/11 patients passed away due to non-cancer related causes. Conclusion HDR mould BT is a valid non-invasive alternative to surgical management of skin cancer and refractory precancerous conditions located on the finger. It has its role particularly in elderly where PS and comorbidities may preclude surgery and short treatment duration can help with patient compliance. With appropriate patient selection skin HDR BT with customized surface moulds offers a good outcome and favourable cosmetic results with function preservation.