Local surgical treatment of cutaneous squamous cell carcinoma: deficits and controversies in the literature

The prognostic impact of primary excision in the treatment of cutaneous squamous cell carcinoma depends on certain tumor characteristics (risk factors), the surgical approach chosen and the subsequent histological examination. For the development of the AWMF (Association of Scientific Medical Societies in Germany) guidelines for squamous cell carcinoma, the most conclusive guidelines available were evaluated using the DELBI tool (German Instrument for the Methodological Appraisal of Guidelines). These were the Scottish and Canadian guidelines as well as the joint guidelines published by EDF, EADO and EORTC. The primary literature on the aforementioned topics that was used for these guidelines included 49 studies and 9 reviews. None of the studies had a prospective, randomized design; 19 studies contained prospective data; 30 studies provided retrospective data. Overall, the results were heterogeneous. Not only were there discrepancies in terms of the validity of the various risk factors for locoregional disease progression - such as dedifferentiation, desmoplasia and perineural invasion - but also with respect to tumor thickness and surgical consequences. Differences were also found regarding the histological processing method used. In general, there are two such methods: conventional histology (bread loaf technique) and complete histological assessment of excision margins. The latter was found to be associated both with low recurrence rates and low metastatic rates, possibly due to the fact that patients treated with the latter method had lower-risk tumors. Publications on bread loaf histology lacked precise information as to how the tissue was actually processed. Likewise, there was a lack of usable data in terms of the surgical margins used in the primary excision. Conclusion: The current literature is inconsistent and insufficient with regard to the various prognostic factors and the surgical approach to cutaneous squamous cell carcinoma.