What is new in the 2020 British guidelines for cutaneous squamous cell carcinoma?

Abstract

Cutaneous squamous cell carcinoma (cSCC) is the second most common form of nonmelanoma skin cancer and accounts for 20% of all cutaneous malignancies. The incidence rate is increasing rapidly and may be associated with significant morbidity, especially in the elderly population. Factors involved in the pathogenesis are exposure to ultraviolet radiation, age, male sex and immunosuppression. In order to support evidence-based clinical decision making, for the British Association of Dermatologists guidelines for the management of people with cutaneous squamous cell carcinoma 2020, systematic literature searches up to January 2020 were undertaken. Systematic reviews and GRADE appraisals for clinical outcomes were performed, focusing on any key developments, to address important, practical clinical questions. This guideline, published in this issue, contains recommendations on classification; diagnosis; referral guidance for primary cSCC; algorithms for staging and management; treatment; and follow-up. What is new in the updated guidelines is the introduction of referral guidance to specialized skin cancer teams for primary cSCC where treatment has been excisional surgery with curative intent. Three risk groups (low, high and very high) were identified according to prognostic factors for poor disease-related outcomes (local recurrence, nodal metastasis, disease-specific death). An algorithm of staging and treatment depending on the extent of the tumour or presence of locally advanced or metastatic cSCC was developed. In order to evaluate treatment strategies, forest plots were produced, in which different treatment options were compared. Whenever possible and appropriate, surgery is still the treatment of choice. As far as surgical treatment is concerned, a standard wide excision is recommended with safety margins of 5 mm to 1 cm depending on risk factors. If margins are difficult to delineate or where tissue preservation is necessary for function, Mohs micrographic surgery should be performed. Adjuvant radiotherapy is recommended for patients with incompletely excised cSCC, where further surgery is not possible (or not chosen by the patient) and for patients at high risk of local recurrence such as perineural invasion or recurrent disease, and for immunocompromised patients. Sentinel lymph node biopsy should only be considered for specific, high-risk, primary cSCC in the context of a clinical trial or in discussion with the specialist skin cancer multidisciplinary team. Immune checkpoint inhibitors are the treatment of choice for advanced cSCC where curative surgery or radiotherapy is not reasonable, except for organ transplant patients or those who have significant autoimmune conditions. In these cases with contraindications, systemic chemotherapy or epidermal growth factor receptor inhibitors may be used. Concerning follow-up, a standardized schedule according to risk group is recommended, ranging from a single post-treatment appointment for low-risk groups, up to post-treatment follow-up appointments for patients with metastatic cSCC at 3-month intervals for 24 months then at 6-month intervals for a further 36 months. These series of recommendations are valuable tools for clinical practice and provide the most current evidence for patient care. The future should rest on gaining further evidence by comparing surgical interventions with modern standardized three-dimensional histopathology, and developing treatment strategies suitable for patients with advanced cSCC who cannot be treated with immune checkpoint inhibitors.