Plattenepithelkarzinom der Haut

Cutaneous squamous cell carcinoma (cSCC) is the second most common malignant skin tumor after basal cell carcinoma, accounting for approximately 20% of nonmelanoma skin cancers. It arises through malignant transformation of keratinocytes in the epidermis and non-cornifying mucous membranes, typically from in situ precursor lesions, such as actinic keratosis, actinic cheilitis and Bowen’s disease. The primary carcinogenic stimulus is UV radiation, which results in the typical distribution pattern with 80% of all cSCC located on skin exposed to UV radiation. In approximately 95% of cases the cSCC is a localized event. Metastasis is rare and mostly occurs through the lymphatic system; however, the risk of metastasis can be up to 20% in some high-risk groups. Prognostic risk factors are tumor thickness, depth of invasion, localization on a mucous membrane, ear, temple, anogenital region, a low degree of differentiation, and perineural invasion. The first-line treatment is excision with clear safety margins, a multistage approach may be necessary in problem areas or with unclear tumor borders. Regional lymph node dissection is recommended if lymph node involvement is present. Radiotherapy can be carried out alone or in combination with surgical treatment with curative or palliative intent or in an adjuvant setting after surgical resection. In cases of locally advanced disease or locoregional recurrence, electrochemotherapy provides an alternative alongside surgery and radiotherapy. Advanced disease can be pharmacologically treated with PD‑1 antibodies, such as cemiplimab or the epidermal growth factor receptor (EGFR) antibody cetuximab. In cases of treatment failure, combination therapy with EGFR blockade and platinum derivatives offer additional options. Current research focuses on the neoadjuvant use of cemiplimab, the combination of EGFR inhibitors with checkpoint blockade and intralesional treatment approaches.