A summer census that may save your life.

As we've pointed out in the past, the most serious of skin cancers -- melanomas -- is increasing at an alarming rate, greater than that of any other form of cancer. Despite widespread warnings in all the news media of sunlight's role as a causative factor, our craze for tanning continues, seemingly unabated -- and skin creams with high levels of sunscreen are being ignored by many in favor of skin creams that promote tanning.

The attitude of those who ignore the warnings and continue to subject themselves to the danger of melanoma and other skin cancers seems to be that "it won't happen to me." But can we predict who is more likely to get skin cancer, and who may not be so much at risk?

The results of a study just published in the Journal of the American Medical Association (May 14) indicates that we can do just that -- and the first step is a "do-it-yourself" project: counting the moles on one's body and identifying any that appear abnormal in size, shape, and color.

The study involved 716 consecutive patients with a diagnosis of melanoma made at the Pigmented Lesion Clinic of the Hospital of the University of Pennsylvania and the Melanoma Clinic of the University of California, San Francisco. With ages ranging from 20 to 79, they were compared with a control group of 1,014 persons of the same age, sex, race, and geographic distribution. All persons in the study underwent an interview, a complete skin examination, and photography of abnormal moles.

The number and type of nevi (the medical term for moles -- singular, nevus) on the entire body were systematically reported. Nevi were classified as nondysplastic and dysplastic. A nondysplastic nevus is completely raised, is symmetric in outline, has smooth borders, and is homogeneously colored. A dysplastic nevus is flat, asymmetric in outline, has irregular borders, and has variable pigmentation. A third type, the congenital nevus, is one that was present at birth, is completely elevated, has separate borders, but has stippled pigmentation (dots of darker color scattered throughout). Nondysplastic nevi were further classified by size: (1) more than 2 mm but less than 5 mm, and (2) 5 mm or larger.

Comparing the number, size, and type of nevi on the melanoma patients with those on the control group, the researchers found that the risk of melanoma related strongly to the number of small nondysplastic nevi, large nondysplastic nevi, and dysplastic nevi:

* Even with no dysplastic nevi, persons with 25 or more small nevi (more than 2 mm but less than 5 mm in diameter) are approximately twice as likely to develop melanoma as those with less than 25.

* Those with large numbers of both small and large nondysplastic nevi were four times at risk.

* Only one dysplastic nevus puts a person at twice the risk, while those with ten or more are twelve times at risk.

* Congenital nevi were not associated with increased risk of melanoma.

Carefully count all the moles on your body (with the help of spouse or a friend, if necessary), paying particular attention to those over 5 mm in diameter (the width of the eraser on an ordinary pencil). Use the "ABCDS of Melanoma" to evaluate them -- asymmetry, border, color, diameter -- and consult your physician if you suspect any of them to be dysplastic nevi.

The authors of the May 14 JAMA article also pointed out that moles tend to increase in number as we grow older, reaching a peak in young adulthood -- and by age 50 they tend to decrease in number. However, persons over 50 with dysplastic nevi are more likely to have persistent large numbers of nevi -- and are at particularly increased risk of melanoma. They also noted that freckling, which reflects sun exposure, puts one at increased risk for melanoma.

Summer is fine for enjoying the outdoors -- but enjoy it safely. Try to stay out of the sun during the height of ultraviolet intensity, the midday hours. Wear protective clothing and use sunscreen lotion with a protection factor of at least 15. Pay attention to those moles!