Of the more than 3 million cases of skin cancer diagnosed every year, more than 80% are basal cell carcinoma, according to the American Cancer Society. These cancers develop within the basal cell layer of the skin, the lowest part of the epidermis.
The second most common type of skin cancer is squamous cell (SCC), which accounts for approximately 15% of skin cancers. It is the second most common type of human cancer with an annual incidence of 700,000 cases.
SCC, also known as squamous cell carcinoma, is a type of skin cancer that begins in the squamous cells, which are thin, flat cells that make up the epidermis, or the outermost layer of the skin. People with SCC often develop scaly, red patches, open sores, or warts on their skin.
Approximately 1 out of 8 cases of actinic keratosis develop into SCC, although most patients present with localized disease that is cured with treatment. Approximately 5% of cutaneous SCC cases recur, metastasize, and can cause death.
Bowen’s disease is a form of SCC in situ that has several topical treatment and surgical options.
Since most cutaneous squamous cell tumors are not likely to metastasize, there may be some compliancy about treating them. There may be a lack of understanding regarding the significance of these lesions by the patient or doctor. There are some clinical clues that may help distinguish low- and high-risk SCC, but biopsy is the only way to know for sure. According to the 2018 National Comprehensive Cancer Network guidelines, low-risk SCCs include:
●Well-defined, primary lesions <20 mm located on trunk or extremities (excluding pretibial, hands, feet, nail units, and ankles).
●Well-defined, primary lesions <10 mm located on cheeks, forehead, scalp, neck, and pretibial.
●Primary tumor
High-risk SCCs include:
●Lesions ≥20 mm located on trunk or extremities (excluding pretibial, hands, feet, nail units, and ankles).
●Lesions ≥10 mm located on cheeks, forehead, scalp, neck, and pretibial.
●Lesions of any size located in the "mask area" (ie, central face, eyelids, eyebrows, periorbital, temple, nose, lips, chin, mandible, pre and postauricular), genitalia, hands, and feet.
●Recurrent tumor
Biopsy of high risk tumors show invasion of local lymphatics. The goals of treatment are to prevent recurrence and preserve cosmetic appearance of the affected area. There are several methods used:
●Surgical excision, including Mohs micrographic surgery
●Curettage and electrodesiccation
●Cryotherapy
●Photodynamic therapy
●Radiation therapy (for nonsurgical candidates)
With high-risk tumors and metastatic tumors, other options apply, and treatment is best undertaken by a group of practitioners, including the dermatologist, pathologist, plastic surgeon, radiotherapist, oncologist, and pharmacist.
Complex cutaneous squamous cell tumors are difficult to treat, can be disfiguring, can metastasize, and cause death. The best approach is often an aggressive surgical and radiologic procedure, unless they are contraindicated.
Cemiplimab is a programmed death receptor-1 (PD-1) blocking antibody indicated for the treatment of patients with metastatic cutaneous SCC (CSCC) or locally advanced CSCC who are not candidates for curative surgery or curative radiation treatments. As an anti-PD-1 monoclonal antibody, it is an immune checkpoint blocker.
This drug has shown impressive results in 2 open label clinical trials. A total of 108 patients (75 with metastatic disease and 33 with locally-advanced disease) were included in the efficacy evaluation. The study’s primary endpoint was objective response rate, or the percentage of patients who experienced partial shrinkage or complete disappearance of their tumor(s) after treatment. Results showed that 47.2% of all patients treated with cemiplimab had their tumors shrink or disappear, most of whom had ongoing responses at the time of data analysis.
Some interesting aspects regarding the pharmacokinetics are that there is no renal or hepatic dose adjustment needed, even in renal or hepatic insufficiency. Secondly, when adverse effects (AEs) develop, the drug is either stopped or continued at the recommended dosage of 350 mg intravenously every 3 weeks. It is not reduced in order to reduce AEs but can be stopped.
The main AEs are typical of PD-1 blockers and include a variety of immune system-mediated AEs, including hepatitis, colitis, pneumonitis, oculitis, apophysitis, thyroiditis. Depending on the seriousness of the AEs, the treatment can be temporarily held or discontinued. Steroids are always administered for immune AEs. Infusion-related AEs can also occur, which may necessitate slowing the infusion.
Pharmacists can play an important role in identifying skin cancer when they see something suspicious or unfamiliar on the skin of a patient. They can suggest seeing a dermatologist with the caveat that they don’t know that is going to be anything serious, but it should be checked.
Having a multispecialty approach to the treatment of cancer of any sort should involve pharmacists who are best able to identify the best way to administer a drug in the right dose and the right setting. They may be the best resource on dosage adjustment and management of adverse effects as well.
