Skin Cosmesis assessment tools and methods in patients with non-melanoma skin cancers treated with radiotherapy: Systematic review on behalf of the ESTRO skin and soft tissue focus group and the GEC-ESTRO head and neck and skin working group.

Non-melanoma skin cancers (NMSC) are highly prevalent and rarely impact mortality; post-treatment cosmesis is paramount as the sequelae of treatment are outwardly visible. There is no agreement on reporting of post-treatment cosmesis, thereby precluding standardised comparisons between treatment modalities. We conducted this systematic review (PROSPERO: CRD420251020168) on behalf of the ESTRO Skin and Soft Tissue Focus Group and the Head and Neck and Skin GEC-ESTRO Working Group to synthesise data on how cosmesis is reported. MEDLINE, Embase, and Web of Science were searched for original studies including cosmesis assessment following radiotherapy for NMSC. Data was collated on the methodology, cosmesis assessment items, and assessment timeframe. Eighty-five studies were included, comprising 17,231 patients treated 1955-2023. Most studies were retrospective (72;85.0%). Three, 26, 18, 2, and 15 studies employed 2, 3, 4, 5, and 6 cosmesis grades; 22 (25.9%) studies did not specify cosmesis grade. Cosmesis assessment methodology was detailed in 63 studies; 25/63 provided insufficient detail to replicate the assessment. Cosmesis assessment items: pigmentation change (87.3%), telangiectasia (84.1%), deformity (66.6%), skin atrophy and fibrosis (60.3%), and epilation (33.3%). Acute (<90d) cosmesis was reported by 25 records, late (>90d) in 35 records, with 32/35 late assessments reporting cosmesis beyond 12 months; 44 (51.8%) did not specify assessment timeframe. The identified skin cosmesis assessments are limited by heterogeneity, subjectivity, and simplified compound grades. Prospective reporting will capture the temporal changes within a newly developed granular and validated skin cosmesis reporting framework.