Surface mold brachytherapy for head and neck non-melanoma skin cancer - local control rates and survival: A retrospective analysis.

Purpose: Non-melanoma skin cancer (NMSC) is the most prevalent cancer worldwide, particularly affecting head and neck region. Surgical excision, especially Moh's microsurgery, is the gold standard for treatment. However, certain patients' factors, such as age, comorbidities, and tumor location, require alternative therapies. Radiotherapy, particularly surface mold brachytherapy, offers a viable option for these inoperable or high-risk surgical candidates.

Material and methods: This retrospective cohort study included 22 patients with histologically confirmed NMSC, treated with high-dose-rate (HDR) surface mold brachytherapy at the Cancer Institute of Iran between 2019 and 2021. The study focused on primary outcomes, including local control and overall survival, with follow-up assessments for acute and late toxicities, treatment response, and cosmetic outcomes.

Results: Twenty-two patients (mean age, 70.94 years) with NMSC were treated. The median lesion size was 2.46 cm. The basal cell carcinoma (BCC) to squamous cell carcinoma (SCC) ratio was 14 : 8. The median maximum depth of clinical target volume was 10 (IQR: 9-15). The median dose was 39 Gy in 13 fractions, with a D₉₀ of 3.04 Gy. Lesions were mainly located on the nose, scalp, and cheek. The 2-year local control rates were 92.9% for BCC and 87.5% for SCC. The 2-year overall survival rate was 71%, with 80% for BCC and 55% for SCC. Eight patients died during the follow-up period, of these, five were due to cancer. Recurrence occurred in one BCC patient (7.1%) and one SCC (12.5%) case. Acute toxicities were mild, and no severe late complications were observed, indicating good tolerance and favorable cosmetic outcomes.

Conclusions: Surface mold brachytherapy using cobalt-60 source is an effective and safe treatment for head and neck NMSC, even in thicker than 5 mm lesions, offering high local control rates and favorable cosmetic outcomes. This technique presents a valuable alternative for patients unsuitable for surgery, warranting further research with larger cohorts for confirmation and treatment protocol optimization.