Treatment of Squamous Cell Carcinoma of the Skin

Localized squamous cell carcinoma (SCC) of the skin is a highly curable disease.[1] There are a variety of treatment approaches to localized SCC, including excision, radiation therapy, cryosurgery, and electrodesiccation and curettage.

There is little to no good-quality evidence that allows direct comparison of outcomes for patients with sporadic, clinically localized SCCs treated with local therapies. A systematic literature review found only one randomized controlled trial in the management of such patients, and that trial compared adjuvant therapy with observation after initial local therapy rather than different local therapies.[2] In that small single-center trial, 66 patients with high-risk, clinically localized SCC were randomly assigned, after surgical excision of the primary tumor (with or without radiation, depending on clinical judgment), to either receive combined isotretinoin (1 mg/kg orally per day) plus interferon alfa (3 × 106 U subcutaneously 3 times/week) for 6 months or undergo observation.[3] In the 65 evaluable patients after a median follow-up of 21.5 months, there was no difference in the combined (primary) end point of SCC recurrence or second primary tumor (45% vs. 38%; hazard ratio, 1.13; 95% confidence interval [CI], 0.53–2.41), or in either of the individual components of the primary end point.[3][Level of evidence B1]

Cemiplimab and pembrolizumab, programmed death receptor-1 (PD-1) inhibitors, are the only systemic therapies for the treatment of locally advanced and metastatic cutaneous SCC. The U.S. Food and Drug Administration (FDA) approved cemiplimab and pembrolizumab based on objective response rates (RRs) from early-phase trials.[4-6][Level of evidence C3] Toxicities associated with checkpoint inhibitors were seen, including death. Clinical trials are recommended to further identify optimal treatment. Ongoing trials include PD-1 inhibitors in the neoadjuvant, adjuvant, and advanced/metastatic settings, as monotherapy and in combinations.