Surgical Margins Identified as a Major Area of Uncertainty in the Management of High-Risk Cutaneous Squamous Cell Carcinoma (cSCC)

The Scottish Intercollegiate Guidelines Network (SIGN) has developed guidelines for primary invasive cutaneous squamous cell carcinoma (cSCC). SIGN 140

Key questions included: (i) Which features, or combination of features, best identify high-risk cSCC? (ii) What are the most effective interventions for management of patients with cSCC? (iii) What is the optimum surgical margin and what histological clearance margins are acceptable?

The evidence base was synthesised in accordance with SIGN methodology (SIGN 50), which complies with the internationally recognised AGREE criteria for guideline development based on a systematic review of the published literature. Databases searched included Medline, Embase, Cinahl and the Cochrane Library. Systematic searches were supplemented by material (mostly historic) identified by members of the development group. Initial searches identified 5712 hits, from which 492 abstracts were screened and 164 studies read in full and critically appraised before 91 were accepted as evidence on which to base recommendations. A systematic review and pooled analysis of observational studies was used as a basis for treatment recommendations.

This process identified those clinical and histopathological features where there is robust evidence for association with poor outcomes (local recurrence, metastasis, disease-related death) allowing recognition of cSCC where referral to a regional skin cancer MDT meeting is appropriate. A minimum dataset highlighting these features would facilitate automatic referral and has been developed.  Four key features; diameter, depth, differentiation and perineural invasion were identified on multivariate analysis as associated with at least 2 of the 3 poor outcomes. Additional independent high-risk features identified were desmoplastic subtype, location on ear and immunosuppression. 

Recommendations and good practice points for surgical margins, Mohs Micrographic Surgery (MMS), radiotherapy and curettage have been developed, but the evidence base for surgical margins and for use of adjuvant radiotherapy was limited, with very little data relating surgical or histological margins to outcomes.  In retrospective analysis most incomplete excisions show persistence at the deep margin suggesting future studies should focus on deep as well as radial margins.  Furthermore, the role of MMS in the management of SCC needs study and clarification.

The SIGN development group, would encourage all skin cancer surgeons to stratify risk of cSCC (as detailed in the SIGN guideline) prior to defining appropriate treatment.

Reference

www.sign.ac.uk

Other Group members 

Charlotte Proby, Andrew Affleck, Alan Evans, Girish Gupta, Khalid Hassan, Lorna Mackintosh, Marie Mathers, Catriona McLean, Colin Moyes, Lisa Naysmith, Jonathan Norris,