Research into the causes, prevention, and treatment of basal and squamous cell skin cancer is going on in many medical centers throughout the world.
Scientists have made a great deal of progress in recent years in learning how ultraviolet (UV) light damages the DNA (genes) inside normal skin cells, and how this might cause them to become cancer cells. Researchers are working to apply this new information to strategies for preventing and treating skin cancers.
Most skin cancers can be prevented. The best way to lower the number of skin cancers and the pain and loss of life from this disease is to educate people about skin cancer risk factors, prevention, and detection. It’s important for health care professionals and skin cancer survivors to remind others about the dangers of too much UV exposure (both from the sun and from man-made sources such as tanning beds) and about how easily they can protect their skin from UV rays.
Skin cancer can often be found early, when it is most likely to be cured. Monthly skin self-exams and awareness of the warning signs of skin cancer may be helpful in finding most skin cancer when they are at an early, curable stage.
The American Academy of Dermatology (AAD) sponsors annual free skin cancer screenings throughout the country. Many local American Cancer Society offices work closely with AAD to provide volunteers for registration, coordination, and education efforts related to these free screenings. Look for information in your area about these screenings or contact the American Academy of Dermatology for more information.
Along with recommending staying in the shade, the American Cancer Society uses a slogan popularized in Australia as part of its skin cancer prevention message in the United States. “Slip! Slop! Slap!®… and Wrap” is a catchy way to remember when going outdoors to slip on a shirt, slop on sunscreen, slap on a hat, and wrap on sunglasses to protect your eyes and the sensitive skin around them.
Squamous cell cancers that start in the genital region account for a large proportion of the deaths from this type of skin cancer. Many of these cancers are related to infection with certain types of human papillomavirus (HPV), which can be spread through sexual contact. Limiting sexual partners and using safer sex practices such as wearing condoms may therefore help lower the risk of some of these cancers.
Vaccines are available to help protect against infection from some types of HPV that can cause certain cancers. The main intent of the vaccines has been to reduce the risk of cervical cancer, but they may also lower the risk of 5 other cancers related to HPV, including some squamous cell skin cancers.
Chemoprevention is the use of drugs to reduce cancer risk. This is likely to be more useful for people at high risk of skin cancers, such as those with certain congenital conditions (basal cell nevus syndrome, xeroderma pigmentosum, etc.), a history of skin cancer, or those with weakened immune systems (such as people who've had organ transplants), rather than for people at average risk of skin cancer.
Some of the most widely studied drugs so far are the retinoids, which are drugs related to vitamin A. They have shown some promise in reducing the risk of squamous cell cancers, but they can have side effects, including possibly causing birth defects. For this reason they are not widely used at this time, except in some people at very high risk. Further studies of retinoids are under way.
Nicotinamide, a form of vitamin B3, has been shown to lower the risk of basal and squamous cell cancers in people at high risk, and with very few side effects, although it hasn’t been studied extensively in people with weakened immune systems.
Targeted drugs called hedgehog pathway inhibitors may help some people with basal cell nevus syndrome. For example, the drug vismodegib (Erivedge) has been shown to lower the number of new basal cell cancers and shrink existing tumors in people with this syndrome. The drug can have side effects, including taste loss and muscle cramps, which can make it hard for some people to take every day. Further research on this and similar drugs is under way.
Other drugs are also being looked at to reduce the risk of basal and squamous cell skin cancers in people at high risk.
Some newer approaches to diagnosing skin cancer don’t require the removal of a skin sample. Examples of such “optical biopsies” include reflectance confocal microscopy (RCM) and optical coherence tomography (OCT). These techniques are now available in some centers and will likely become more common in the coming years.
While it’s not common for basal or squamous cell cancers to spread to other parts of the body, these cancers can be hard to treat once they do. Doctors are now looking for better ways to determine which skin cancers are likely to grow and spread more quickly, and therefore might require more intense treatment. For example, some research has shown that squamous cell skin cancers with lower levels of the INPP5A protein seem to be more likely to spread. More research is needed before this type of tumor testing becomes commonly used.
Current local treatments such as surgery and radiation therapy work well for most basal and squamous cell skin cancers. Still, even some small cancers can be hard to treat if they’re in certain areas. Newer forms of non-surgical treatment such as new topical drugs, photodynamic therapy, and laser surgery may help reduce scarring and other possible side effects of treatment. The best way to use these treatments is now being studied.
Most basal and squamous cell skin cancers are found and treated at an early stage, when they are likely to be cured, but some can grow into other areas or spread to other parts of the body. These cancers can often be hard to treat with current therapies such as radiation and chemotherapy.
Squamous cell cancers: Several studies are testing newer targeted drugs for advanced squamous cell cancers. For example, cells from these cancers often have too much of the EGFR protein on their surfaces, which can help them grow. Drugs that target this protein, such cetuximab (Erbitux), are now being tested in clinical trials, both alone and combined with other treatments.
Immunotherapy is another newer approach to treating some advanced squamous cell cancers. Drugs called immune checkpoint inhibitors are now coming into use as an option to treat some of these cancers.
Basal cell cancers: It’s very rare for basal cell cancers to reach an advanced stage, but when they do, these cancers can be hard to treat. Vismodegib and sonidegib, drugs that target the hedgehog signaling pathway in cells, may help some people (see Targeted Therapy for Basal and Squamous Cell Skin Cancers). Other drugs that target this pathway are now being studied as well.
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Cumsky HJL, Costello CM, Zhang N, et al. The prognostic value of inositol polyphosphate 5-phosphatase in cutaneous squamous cell carcinoma. J Am Acad Dermatol. 2019;80:626-632.
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National Comprehensive Cancer Network (NCCN). Practice Guidelines in Oncology: Basal Cell Skin Cancer. Version 1.2019. Accessed at www.nccn.org/professionals/physician_gls/PDF/nmsc.pdf on June 4, 2019.
National Comprehensive Cancer Network (NCCN). Practice Guidelines in Oncology: Squamous Cell Skin Cancer. Version 2.2019. Accessed at www.nccn.org/professionals/physician_gls/pdf/squamous.pdf on June 4, 2019.
Saslow D, Andrews KS, Manassaram-Baptiste D, et al. Human papillomavirus vaccination 2020 guideline update: American Cancer Society guideline adaptation. CA Cancer J Clin. 2020; DOI: 10.3322/caac.21616.
Stasko T, Hanlon AM. Prevention and management of skin cancer in solid organ transplant recipients. UpToDate. 2019. Accessed at https://www.uptodate.com/contents/prevention-and-management-of-skin-cancer-in-solid-organ-transplant-recipients on June 4, 2019.
Last Revised: July 8, 2020