Preventing actinic keratosis and non-melanoma skin cancer

Dr Ian Webster highlights the impact of actinic keratosis and non-melanoma skin cancer and the use of medical sunscreens containing photolyase for prevention and treatment.

Skin cancers are the most common cancers worldwide and in SA. In SA, there are approximately 20 000 reported cases of skin cancer per year. Skin cancers are divided into two groups, namely: malignant melanoma and non-melanoma skin cancer.

Fortunately, malignant melanoma isn’t as common as non-melanoma skin cancer (NMSC), but it may be fatal. Non-melanoma skin cancers comprise basal cell carcinomas (BCC), squamous cell carcinomas (SCC) and other rare skin cancers (RSC). 

Although you’re less likely to die from a NMSC, they may be locally aggressive, can be cosmetically disfiguring and often require more advanced plastic surgery for removal. For example, MOHs micrographic surgery. Older, white males are more likely to develop NMSC in SA.

Unfortunately, we don’t have very accurate data as to the prevalence of NMSC in SA. However, one study showed that the white population was most susceptible to skin cancer followed by the coloured, Asian and black populations. The age standardised NMSC incidence rate for SA was reported to be 4.76 per hundred thousand for non-whites and 19.2 per hundred thousand for whites. In other words, the paler your skin, if you’re male and if you have had excess sun exposure over the years, the more likely you’re to develop NMSC.

Squamous cell carcinoma is the most common subtype in the black population in SA and this may be linked to a higher prevalence of HIV infection and oculocutaneous albinism.

Actinic keratoses (AK) 

Actinic or solar keratoses are small, scaly red bumps usually on the exposed areas of persons with a fair skin. If left untreated, approximately one in every 10 actinic keratoses may progress onto a squamous cell carcinoma.

Prevention and treatment

Literally from birth, the following are good habits, and studies have shown that if you do all of the below, the number of new AK and NMSC will decrease.

Sun avoidance

Seek shade and avoid the sun between 11am and 4pm or earlier and later if the sun is already hot. 

Sun protection

Wear a broad-brimmed hat, good quality sunglasses and the appropriate UV-protected clothing.

Sunscreens

Use a high factor, broad-spectrum sunscreen on all the exposed areas. After swimming or if sweating, sunscreen should be applied immediately, otherwise routinely apply every two hours.

Newer generation sunscreens not only contain high factor, broad-spectrum filters against UV radiation, but many also contain antioxidants such as Fernblock, vitamin C and E. These are therefore protective against high-energy visible light and infrared radiation. In addition, some contain enzymes that can repair DNA damage in the epidermis of the skin. These enzymes include photolyase and Genorepair Complex.

Photolyase

Plankton are microorganisms that are permanently exposed to the sun; its DNA contains photolyase which provides fool-proof protection against the sun’s harmful effects and helps to repair solar damage that the body can’t.

Genorepair Complex

A repair complex for comprehensive DNA protection consisting of three enzymes, photolyase, glycosylase, and endonuclease, that works by activating the three mechanisms of DNA repair, prevents cell damage and strengthens natural skin repair mechanisms.

Recommended products: 

• ISDIN Eryfotona AK-NMSC SPF 99 
• Heliocare 360° MD AK Fluid SPF 100+
• Lamelle Helase 50

Nicotinamide

Studies have shown that nicotinamide (vit B3) taken orally is safe and effective in reducing the rates of NMSC and AK in high-risk patients. It boosts cellular energy in photo-damaged skin, encourages DNA repair and has anti-inflammatory effects. However, it’s important to take it at the correct dosage: 500mg both in the morning and the evening to get the desired benefits. At this dosage the side effects are virtually nil. 

Recommended product: 

• Dermastore Nicotinamide capsules 500mg 

Medical treatment

AK

Cryotherapy (application of liquid nitrogen via a cryospray gun or cotton wool applicator) is the treatment of choice if only a few AK are present on the body. 

If the AK are numerous and widespread then field treatment with 5-fluorouracil ointment, imiquimod cream or photodynamic (PDT) treatment is indicated.

BCC

If the BCC is superficial and in a favourable anatomical site, imiquimod cream or PDT may be recommended. Deeper BCC requires surgical excision. 

SCC

The standard treatment is surgical excision with or without radiotherapy. 

References

Int.J.Environ.Res.Public Health 2020

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