Managing Close and Involved Margins Following Excision of Non-Melanoma Skin Cancer: A Retrospective Cohort Study

Management of close or involved margins following non-melanoma skin cancer (NMSC) excision remains variable in Australia. While national guidelines emphasise complete excision, they provide limited direction when margins are close or involved. We aimed to validate a structured, evidence-informed algorithm to guide decision making and reduce recurrence risk.

This retrospective cohort study was conducted across two tertiary centres in Brisbane, Australia. Adult patients who underwent excision of biopsy-proven basal cell carcinoma (BCC) or cutaneous squamous cell carcinoma (cSCC) between 1 April 2018, and 1 July 2021, were included. Of 828 excised lesions, 89 had close or involved margins. Management pathways and 2-year recurrence-free survival (RFS) outcomes were analysed. Superficial lesions (intra-epidermal carcinoma and superficial BCC) were excluded from recurrence analysis. Fisher's exact test was used to assess differences in recurrence rates.

Eighty-seven of 89 lesions (97.8%) were managed in accordance with the proposed algorithm. These cases achieved a 2-year RFS rate of 98.8%. The two cases managed outside algorithm recommendations both recurred. This difference was statistically significant (p = 0.002). Outcomes compare favourably with published Australian data.

This algorithm-based, risk-stratified approach supports consistent and safe management of NMSC lesions with close or involved margins. Its real-world application achieved high RFS. Broader implementation and prospective validation may contribute to optimising outcomes and guiding future practise.