Computed tomography-based flap brachytherapy for non-melanoma skin cancers of the face

Abstract

Purpose: Non-melanoma skin cancers of the face are at high-risk for local recurrence and metastatic spread. While surgical interventions such as Mohs microsurgery are considered the standard of care, this modality has the potential for high rates of toxicity in sensitive areas of the face. Catheter flap high-dose-rate (HDR) brachytherapy has shown promising results, with high rates of local control and acceptable cosmetic outcomes.

Material and methods: Patients with non-melanoma skin cancers (NMSC) located on the face were treated with 40 Gy in 8 fractions, given twice weekly via catheter flap HDR brachytherapy. Clinical target volume (CTV) included the visible tumor plus a margin of 5 mm in all directions, with no additional planning target volume (PTV) margin.

Results: Fifty patients with 53 lesions on the face were included, with a median follow-up of 15 months. All were considered high-risk based on NCCN guidelines. Median tumor size and thickness were 18 mm and 5 mm, respectively. Median PTV volume and D₉₀ were 1.7 cc and 92%, respectively. Estimated rate of local control at twelve months was 92%. Three patients (5%) experienced acute grade 2 toxicity. Two patients (4%) continued to suffer from chronic grade 1 skin toxicity at 12 months post-radiotherapy (RT), with an additional two patients (4%) experiencing chronic grade 2 skin toxicity. Forty-nine lesions (92%) were found to have a good or excellent cosmetic outcome with complete tumor remission.

Conclusions: CT-based flap applicator brachytherapy is a valid treatment option for patients with NMSC of the face. This modality offers high rates of local control with acceptable cosmetic outcomes and low rates of toxicity.

Keywords: HDR; brachytherapy; catheter flap; face; flap; non-melanoma; radiation; skin cancer.

Fig. 1

Mask areas of face. Area M: forehead, scalp, cheek,and neck. Area H: periorbital, eyelids, periauricular, temple,ears, central face, lips, and nose. Photo courtesy of Stein et al. [4]

Fig. 2

An example of an 82-year-old female patient, who presented with a lesion of the medial inferior eyelid (A). Flap applicator was placed, and thermoplastic mask was created to secure its position (B). Simulation CT was obtained (C). 40 Gy in 8 twice weekly fractions was delivered using HDR-brachytherapy. During the final week of treatment, she developed grade 1 conjunctivitis, which was treated with a two-day course of antibiotic/steroid eye suspension. On initial follow-up one-month post-treatment, her conjunctivitis had resolved, and the lesion had diminished in size. By follow-up at seven months, her lesion had completely resolved, with minimal hypopigmentation or scarring (D)