Guidelines for the diagnosis and treatment of cutaneous squamous cell carcinoma and precursor lesions

Abstract

Carcinomas are malignant tumours of epithelial origin. Cutaneous carcinomas are primarily of keratinocytic origin (epidermal or follicular keratinocytes) or of adnexal glandular origin. Keratinocytic carcinomas include basal cell carcinomas (BCC) and cutaneous squamous cell carcinomas (SCC). BCC and SCC are by far the most common forms of cancer in humans. Paradoxically, as they are not generally recorded in cancer registers, their importance in terms of public health and their economic impact on healthcare systems are widely underestimated. The relative incidences of BCC and SCC differ according to whether SCC is grouped among lesions with the same oncogenesis or not, namely actinic keratosis (AK) and Bowen's disease (BD) (see below). If AK is included in this group, SCC is the most common form of human cancer. If it is excluded, while being responsible for the majority of deaths attributable to non-melanoma skin cancers (NMSC), SCC is the second most important form of cancer in terms of frequency. Although the majority of SCC cases are not life-threatening, this carcinoma is likely to metastasize, particularly if initial treatment was inadequate. The SFD has drawn up guidelines for the treatment of BCC (2004) and melanoma (2005). The present work is the logical continuation of this initiative. It aims to provide practitioners treating skin cancer patients with a series of recommendations based on scientific evidence or, when this was not available, on expert consensus. Medical textbooks refer to a wide array of clinical and histological forms of SCC. The prognosis for these different forms varies according to whether therapy has been specifically codified or not. In addition, the terminology used to describe these lesions varies, which may lead to confusion and prevent use of a clear decision-making tree. The TNM classification, developed by AJCC/IUAC/UICC, which is used for all skin cancers except melanoma, is not suitable for SCC. It does not take into account the multiple prognostic criteria identified in the literature. Many treatments are currently available, in particular, for SCC precursor lesions, but the criteria of choice and the methods of application are generally far from clear for practitioners. This results in major disparities in terms of therapeutic management. The present guidelines deal with the treatment of SCC and precursor lesions in immunocompetent adults in France, in both ambulatory and hospital settings. The aims are as follows: to clarify the terminology used to describe the different forms of SCC and of their precursors AK and BD; to propose a prognostic classification of SCC that takes into account various clinical and histological factors; to recommend diagnostic and therapeutic measures for SCC based on previously identified prognostic factors; to optimize diagnostic and therapeutic management of AK and BD in accordance with recent data in the literature; to provide an overview of the principles for primary prevention of SCC and precursor lesions (based on the same methods), and for screening of subjects identified as at risk for SCC (other than genodermatosis and immunosuppression). Due consideration has been given to the fact that patients with SCC, AK or BD are generally (very) elderly. This creates problems in terms of screening for lesions, and for amenability to care and treatment (poor compliance to certain treatments, difficulty in carrying out sequential physical treatments, refusal of onerous surgery, or surgery requiring multiple operations). The oncogeriatric dimension of therapy has thus been taken into account. These guidelines do not address the following issues: SCC of the nails or the genital and anal mucosa; SCC in immunosuppressed patients, particularly transplanted patients; SCC in the context of certain genodermatoses. The levels of evidence and grades used are those defined by the HAS [French Health Authority] (Annex 1). The literature on SCC generally carries low levels of evidence and, except where otherwise stated, the recommendations included in these guidelines are of grade C. These guidelines have been created in the form of Recommendations for Clinical Practice in accordance with the ADAPTE method.2 As its name suggests, this method advocates the adaptation to a particular situation – in this case, medical practice in France in 2008 – of one or more guidelines on the same theme, drawn up previously or in other countries. Medical societies concerned with SCC were consulted on the initiative of the French Dermatology Society (SFD), the sponsor, to define the scope of the guidelines, identify work performed on the subject and recommend professional members for the organizing committee (OC), the working group (WG) and the reading group (RG). Mention must be made of the difficulty of recruiting general practitioners to these groups, despite the fact that, in view of the subject, their assistance is vital. In the Spring of 2007, the Dermatology Recomme