Preventing Skin Cancer

Summarized by Robert W. Griffith, MD
February 1, 2002 (Reviewed: February 22, 2004)

Introduction

In an earlier article, we summarized the main features of the three common types of skin cancer -- melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). In all three types, the ultraviolet radiation of sunlight is well established as an etiological agent. The occurrence of precancerous lesions makes the case for annual, or at least 3-yearly, complete skin examinations.

Actinic keratosis

Actinic keratoses (sometimes called solar keratoses) serve to document the exposure to solar radiation over the years. These lesions represent the cumulative total of ultraviolet light exposure, and thus the risk for non-melanomatous types of skin cancer.

The lesions are irregular, ill-defined, maculo-papular eruptions that are pale brown or flesh-colored; sometimes they are scaly, or can be dark in color. Less than one in 1,000 will transform to SCC within a year. However, they should be removed when diagnosed.

One-time cryotherapy (liquid nitrogen) is the treatment of choice, although curettage or surgical dissection may occasionally be used for larger lesions. Chemical destruction with 5-fluorouracil is an alternative if there are many lesions involving the head and neck; application is twice daily for 2 to 5 weeks, and may lead to secondary infection and inflammation. Cosmetic considerations have led to development of other types of removal -- e.g. chemexfoliation (chemical peeling) and facial dermabrasion.

Changes in actinic keratosis suggestive of transformation to SCC include pain, erythema, ulceration, induration, hyperkeratosis, and increasing size. Up to 60% of SCC occur at a site of previous actinic keratosis.

While actinic keratosis is a precursor to BCC, it's becoming recognized that severe sunburns in childhood and adolescence may also be responsible for some cases of BCC, as well as most cases of melanoma.

The most important risk factor

It's been shown that 80% of lifetime sun exposure is acquired before age 18. This makes sunburn in childhood and adolescence the prime target for preventive measures. Here is a "safe sun" guideline that physicians can use for their patients:

• Sun exposure during the peak ultra-violet-B (UV-B) hours (10 am to 4 pm) should be avoided or minimized.
• Sunscreen with a solar protection factor (SPF) of at least 15 should be applied generously
• In addition to sunscreen, people should wear wide-brimmed hats, sunglasses, and protective clothing (e.g. tightly woven fabrics and long-sleeved shirts) when sun exposure during peak UV-B hours cannot be avoided
• Deliberate sun tanning and use of tanning parlors should be avoided

Preventive counseling along these lines is likely to make patients more aware of the risks of skin cancer, and lead to more regular skin check-ups and earlier reporting of malignant lesions.

Other risk factors

There are some risk factors that cannot be influenced by lifestyle changes. Age, as we have indicated, is a risk factor for BCC and SCC, but less so for melanoma, which has a peak frequency in early adulthood. A family history plays a role in the occurrence of melanoma, but not in BCC and SCC. Male gender is a weak risk factor for all skin cancers.

The following risk factors are linked to the role of UV-B exposure: ethnicity (cancer more common in whites), geographic location (risk greater near the equator), and occupation (outdoor workers at greater risk).

Some chemicals can increase the risk for BCC and SCC: coal-tar products, tobacco, and psoralens (e.g. PUVA therapy). Radiation may increase the risk of melanoma. Finally, certain illnesses can increase the risk of BCC and SCC (chronic skin infections, xeroderma pigmentosum, human papillomavirus), and melanoma (xeroderma pigmentosum, immunosupression for any cause, and other malignancies).

Summary

Common-sense avoidance of the sun's rays is the main measure for preventing skin cancers. This necessitates educational campaigns that have to be repeated, again and again. Early recognition of actinic keratosis, with prompt treatment, will prevent a number of cases of BCC and SCC.

Improved awareness of skin cancers will lead to regular full-body check-ups, and should also result in earlier reporting of potentially malignant changes in naevi and actinic keratoses. This is one area in which good health education can really make a difference in saving lives and reducing morbidity.

A picture is worth a hundred words, especially when it comes to dermatology. So go to the online Atlas of Dermatology -- see the link below -- to check up on the various precancerous lesions that occur in the skin.

Sources

• Overview of skin cancer detection and prevention for the primary care physician. AJ. Bruce, DG. Brodland, Mayo Clin Proc, 2000, vol. 75, pp. 491--500



• Early detection and treatment of skin cancer. AF. Jerant, JT. Johnson, CD. Sheridan, TJ. Caffrey, Am Fam Physician, 2000, vol. 62, pp. 357--368

Related Links
Detecting Skin Cancer
Online Atlas of Dermatology
Welcome to Dermatlas

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