Cancers de la peau

Treatment for SCC

The goals of treating squamous cell skin cancer (SCSC) are to remove the tumour, preserve function, and prevent skin damage. Most people diagnosed with SCSC can be cured by surgically excising or removing the tumour(s). Below are descriptions of approved and available treatments for SCSC. It is important to note that not all of the treatment options described will apply to every situation. Your healthcare providers will determine which treatments apply to your SCSC.

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Curettage and Electrodesiccation: For curettage, the clinician scrapes the cancer from the skin with a sharp, looped tool called a curette, then immediately cauterizes the site. Electrodessication, the second step, prevents bleeding at the site without using sutures and burns off residual cancer cells. The wounded site will then be covered with gauze and heals with time. This procedure is a technique effective for low-risk SCSC. Areas with hair growth are unsuitable for this technique due to the potential for inadequate tumor removal and the subsequent risk of spreading.

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Shave Excision or Standard Surgical Excision: With these techniques, the clinician removes the suspicious skin lesion. The difference between the names includes the amount of tissue removed, whether stitches are necessary for the wound, and whether a noticeable scar will develop. A shave excision is superficial or closer to the skin’s surface and usually applies to tiny, low-risk lesions. A standard surgical excision removes more tissue, may need stitching, and produces a noticeable scar. Standard excision is recommended as the primary treatment for low-risk SCSCs. After removing the tissue, the sample is sent to a laboratory for examination, where it will be assessed to make sure all the cancer has been removed along the margins of the tumour. On your pathology report, the terms negative, clean, not involved, or clear margins indicate that the tumour is surrounded by normal tissue and has been adequately removed. If the areas around the tumour do not show healthy cells, you may need to have further excision during another appointment to obtain clear margins. Other techniques may be recommended if positive margins are observed. In some cases, reconstruction, tissue repair, or skin grafting are undertaken after clear margins are achieved. 

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Mohs Micrographic Surgery: Mohs surgery is the preferred treatment option for people with SCSC because it allows clinicians to achieve a complete removal of all cancer cells observed. Mohs improves the outcomes of removing all of the tumor cells present because the process requires a continuous reexamination of the tissue. Although it is a superior technique, it requires a certified specialist, and it is not appropriate in all cases. Mohs surgery involves removing thin layers of skin one layer at a time and examining each layer under a microscope to determine if any cancer remains. Mohs incorporates a process by which the surgically removed tissue is carefully mapped, color-coded, and microscopically examined. Mapping allows the surgeon to pinpoint the location of the cells on the image back to the skin site. The mapped tissue edges and undersurface are then examined under a microscope to determine whether these areas contain normal or cancer cells. If cancer cells appear, the map specifies the region requiring additional tissue removal. Mohs surgery is complete once the tissue edges and undersurface are absent of cancer cells. Potential side effects from surgery include bleeding, adverse reactions to medications, or difficulty closing the wound, sensory nerve damage, lymphedema, and disfigurement.

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Radiation Therapy: Radiation involves concentrating a beam of energy on the tumour. The intense radiation will cause massive damage inside the cancer cells, which will lead to their death. This type of therapy is administered by a radiation specialist at a hospital or treatment centre and may last six or more weeks. Radiation therapy schedules vary among patients, and treatment could occur daily or two to four treatments per week, depending on each case. Caution is warranted when using this treatment because it increases the risk of developing secondary skin cancer within the radiation field. Side effects include poor cosmetic consequences, such as skin pigmentation changes, widening of blood vessels, non-healing ulcers, tissue death, and scarring. If positive margins with tumour cells are detected following surgery, radiation therapy may be recommended as “adjuvant” therapy (meaning an additional or supplement) because it improves the outcome of treatment. A radiation oncologist will determine appropriate options for radiation therapy in each case.

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Precancer Treatments Applied to the Skin

In patients with SCSC precancers, called actinic keratoses, there are many options for topical therapy. These include the options below:

• 5-fluorouracil is a traditional chemotherapy but is supplied in more than one formulation, depending on the type of cancer for which it is needed. For skin cancer, it can be applied as a topical cream directly to the skin twice daily to destroy actinic keratoses. 

• 5-fluorouracil/calcipotriol (calcipotriene) is a topical ointment mixture of 5-fluorouracil cream and calcipotriene. Calcipotriol is a derivative of vitamin D and is reported to enhance the immune system.

• Imiquimod is a drug that activates and amplifies the immune system. It is prescribed as a topical cream for actinic keratoses. 

• Tirbanibulin is a topical solution to treat actinic keratosis on the face and scalp. The goal is to prevent these lesions from developing into invasive SCSC.

• Diclofenac is a non-steroidal anti-inflammatory agent that has been long-established and used to reduce pain and inflammation.

• Chemical peel with trichloroacetic acid may be appropriate for people with extensive actinic keratoses on their face and scalp. This treatment should be performed by a professional and will cause the top layer of skin to come off.

• Photodynamic therapy combines medicine with light to kill the tumour cells. Superficial tumours (those that are small and/or not deep) are ideal for this therapy. Light cannot completely penetrate deep or large tumours.

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Medications for Regional and Metastatic Squamous Cell Skin Cancer

The two most commonly given treatments that are approved and available for regional and metastatic SCSC are cemiplimab (Libtayo) and pembrolizumab (Keytruda). Both are systemic therapies (those that spread throughout the body to treat cancer) and may be combined with other types of therapy. 

• Cemiplimab (Libtayo) is an intravenous medication indicated for the treatment of patients with SCSC that has spread regionally or metastatic SCSC who are not candidates for curative surgery or curative radiation. Cemiplimab is a drug designed to generate an immune system reaction to the tumour cells. This drug is also approved for basal cell carcinoma and some non-small cell lung cancers. The most common side effects include rash, itching, diarrhea, fatigue, muscle/joint pain, and/or gland dysfunction. Warnings that accompany this medication include the possibility of severe, potentially life threatening inflammatory reactions, a reaction during the infusion, and embryo toxicity.

• Pembrolizumab (Keytruda) is an intravenous medication approved for the treatment of patients with recurrent or metastatic SCSC or locally advanced SCSC that is not curable by surgery or radiation. The side effects of this drug are usually similar to mild allergic reactions and inflammation because of the immune system stimulation and may include skin rash, intestinal issues, organ problems, and reactions on infusion. Usually, these are mild but could result in the discontinuation of the drug.

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Clinical Trials

Depending on your SCSC type, a clinical trial may open for enrollment and appropriate to consider. Clinical trials are experimental research studies that test a new approach or therapy under the guidance of clinicians and a medical review board. These trials are entirely optional for patients. If current and approved treatments are not effectively treating your cancer, clinical trial options may be worthwhile to investigate.

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Sources: AIM at Skin Cancer, "How SCSC is Treated." [link: https://aimatskincancer.org/squamous-cell-skin-cancer/treatment-options/]

AIM at Skin Cancer, "Side Effects of Treatment - SCSC." [link: https://aimatskincancer.org/squamous-cell-skin-cancer/side-effects-of-treatment-scsc/]