Definitive HDR Brachytherapy for Non-Melanomatous Skin Cancers: an Effective and Efficient Cure

Abstract

Non-melanomatous skin cancer (NMSC) is the most common malignancy with high cure rates using surgery or radiation. In certain patients/anatomical sites, surgery can lead to suboptimal cosmesis or concerns of wound healing. External beam radiation (EBRT) can be time intensive and has dosimetric limitations when treating irregular surfaces. Surface HDR brachytherapy (BT) offers dosimetric advantages over EBRT and a more timely and cost effective treatment, although there are limited data on its utility. We report on our institutions’ experience treating patients’ NMSC lesions with HDR BT, reporting disease outcomes, toxicities, and cosmesis. Eighty-one NMSCs in 60 patients (median age 83) have been treated since 2015 with HDR BT, mostly using a Freiburg flap surface applicator. Most common prescription dose was 32-40 Gy in 8-10 fractions twice weekly to the lesion with margin at 3-5mm depth. Patient and treatment data were recorded in a prospectively maintained database. Physician graded (PG) toxicities (CTCAE v4.03) were recorded during treatment and at early (within 3 mo of treatment) and late (>3 mo) follow-up (FU) visits, as was PG and patient reported (PR) skin cosmesis. Univariable generalized linear mixed effects models were used to estimate the odds of have suboptimal cosmesis (fair-poor vs good-excellent) with certain patient/disease risk factors. Lesions were mostly squamous cell carcinoma (CA) (35%) and basal cell CA (52%), with 13% other histologies. Lesion sites included scalp (20%), head/neck (40%), extremities (35%) and trunk (5%). 51% of patients had vascular disease, 26% were smokers, and 20% had autoimmune conditions. Lesion size ranged from 4 mm to >5 cm (median 1.1-2cm). BT was definitive in 92% and adjuvant in 8% of lesion treatments. At a median FU of 12 months, local disease control was 97.3% (74/76 patients with at least 3 mo FU). One failure was in a previously irradiated, recurrent squamous cell CA of the eyelid. Early Grade (G) 2 and G3 PG skin toxicities were 5.6% and 2.8% and late G2 and G3 toxicities were 1.3% and 0%, respectively, with no G4 toxicities. PR cosmesis was reported as good to excellent in 92% and 96% at early and late FU, respectively. PG cosmesis was good to excellent in 86% and 98% at early and late FU, respectively. This included patients with advanced vascular disease (51%), lesions on lower extremities (26%), difficult location lesions on the nose/ear (26%), and immunocompromised patients (20%). The odds of less than good cosmetic outcome at early FU were slightly higher for smokers (OR 4.72 (0.82-27.2 CI), p=.08), approaching significance. No other tested lesion or patient characteristic was associated with poorer cosmesis. Organ preservation, where applicable (i.e. nose, ear) was 100%. HDR BT is a good treatment option for NMSC with excellent local control, low toxicity, and overall great PR and PG cosmesis. Longer followup is awaited. Further studies comparing HDR BT to surgery and EBRT are underway at our institution.