The Multidisciplinary Management of Cutaneous Squamous Cell Carcinoma: A Comprehensive Review and Clinical Recommendations by a Panel of Experts

Abstract

Cutaneous squamous cell carcinomas (CSCC) account for about 20% of all keratinocyte carcinomas, which are the most common form of cancer. Heterogeneity of treatments and low mortality are a challenge in obtaining accurate incidence data and consistent registration in cancer registries. Indeed, CSCC mostly presents as an indolent, low-risk lesion, with five-year cure rates greater than 90% after surgical excision, and only few tumors are associated with a high-risk of local or distant relapse; therefore, it is particularly relevant to identify high-risk lesions among all other low-risk CSCCs for the proper diagnostic and therapeutic management. Chemotherapy achieves mostly short-lived responses that do not lead to a curative effect and are associated with severe toxicities. Due to an etiopathogenesis largely relying on chronic UV radiation exposure, CSCC is among the tumors with the highest rate of somatic mutations, which are associated with increased response rates to immunotherapy. Thanks to such strong pre-clinical rationale, clinical trials led to the approval of anti-PD-1 cemiplimab by the FDA (Food and Drug Administration) and EMA (European Medicines Agency), and anti-PD-1 pembrolizumab by the FDA only. Here, we provide a literature review and clinical recommendations by a panel of experts regarding the diagnosis, treatment, and follow-up of CSCC.

Keywords: anti-PD-1; cemiplimab; cutaneous squamous cell carcinoma; guidelines; immune checkpoint inhibitors; immunotherapy; keratinocyte carcinomas; recommendations; skin cancer.

Figure 1

Algorithm of management of patients with actinic keratosis. Maintenance therapy may include agents such as nicotinamide, polypodium, and photoliasis. Abbreviations: 5FU: 5-fluororacil; AK: actinic keratosis; Crio: cryotherapy; CSCC: cutaneous squamous cell carcinoma; DL: day light photodynamic therapy; IMQ: imiquimod.

Figure 2

Algorithm for the follow-up of patients with cutaneous squamous cell carcinoma. Dermatologic inspection should always include lymph node palpation. Clinical evaluation and imaging should be tailored to patient life expectancy and comorbidities. Additional exams may be necessary according to symptoms or clinical suspect. Abbreviations: AK: actinic keratosis; CSCC: cutaneous squamous cell carcinoma; laCSCC: locally advanced cutaneous squamous cell carcinoma; mCSCC: metastatic cutaneous squamous cell carcinoma.