Weekly High-Dose Rate Brachytherapy Via Surface Applicator For Non-Melanoma Skin Cancers In The Elderly

Abstract

Among patients treated with brachytherapy for non-melanoma skin cancers (NMSCs), including squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), there exists a wide variety in dose, fractionation, and schedules employed. We retrospectively analyzed a hypofractionated regimen delivering 36 Gy in 6 weekly fractions to assess its safety and efficacy for the treatment of NMSCs in the elderly. All elderly (> 70 years old) patients treated in 2016 to 2019 with follow-up were included. In total, 46 patients with 63 NMSC lesions were treated using iridium-192 high-dose rate brachytherapy (HDR) delivered with custom molds containing catheters to encompass the tumor or tumor bed with a margin. The dose scheme employed was a weekly hypofractionated regimen of 36 Gy in 6 weekly fractions. Only 7 lesions (11.1%) underwent a more extensive excision than a biopsy. Acute and late toxicity were graded as per CTCAE version 5. Cosmesis was graded as “excellent” (similar to surrounding untreated skin), “good” (minimal changes), or “poor” (extensive telangiectasia, ulceration, or scar tissue). Kaplan-Meier curves were used to assess local control. Median age at treatment initiation was 85.8 years (range: 71.2-98.7), and 20 patients (43.5%) were female. Performance statuses ranged from 0 to 4 with 30.4% ECOG 0-1, 41.3% ECOG 2, and 28.3% ECOG 3-4. Median time from first treatment to last was 35 days (range: 28-70), and median follow-up was 8.6 months (range: 1.3-35.9). 35 lesions (55.6%) were BCC, and most lesions (81.0%) were located on the head and neck, including 20 on the nose (31.7%). All patients experienced acute toxicity with grade 1 occurring in 66.7%, grade 2 in 28.6%, and grade 3 in 4.8%. Lesions were not evaluated during follow-up in 5 cases (7.9%), and grade ≥ 2 late or persistent toxicity occurred in 12.1%. Overall cosmetic outcome was determined to be “excellent” or “good” following 54 treatments (93.1% of evaluable lesions). There was a higher incidence of “poor” cosmesis for lesions located on the lower extremities (33.3% vs. 3.8%, p = 0.049) and larger lesions (median: 11.8 vs. 5.1 cc, p = 0.031). Recurrence occurred in 3 lesions (4.8%) with 1 BCC on the bridge of the nose experiencing failure 8 months after completing treatment and 2 SCC lesions exhibiting persistent disease initially thought to be a poor cosmetic outcome, 1 on the nasal ala (confirmed at 6 months) and 1 on the scalp vertex (confirmed at 18 months). Estimated local control was 100% at 6 months, 94.5% at 12 months, and 88.2% at 24 months. Five patients (10.9%) have died since completing treatment, none due to disease progression. Our results suggest a hypofractionated regimen consisting of 36 Gy in 6 weekly fractions delivered with high-dose rate brachytherapy via surface applicator represents both a safe and an effective treatment of non-melanoma skin cancers in elderly patients.