For many, summertime means soaking up the rays during long days at the beach or pool. However, dermatologists continually advise us to shun tanning and slather on sunscreen to lower the risk of developing skin cancer, especially melanoma, the most deadly form. Melanoma is the sixth most common cancer in the United States, and its incidence continues to rise. Because a tumor's thickness is strongly related to long-term survival, researchers at Boston University wondered whether the proportion of different types and thicknesses of melanomas has changed over time.

What the researchers wanted to know: What are the trends in melanoma diagnosis?

What they did: Using a national database, researchers analyzed data from 35,028 patients with invasive melanoma from 1988 to 1999. They tracked the incidence of the cancer over time in addition to the types and thicknesses of the tumors diagnosed. They also analyzed characteristics of the cancers with respect to the age and sex of the patients.

What they found: Looking at three-year periods, the researchers found that the number of new melanomas increased 60 percent from the 1988–1991 period to the 1996–1999 period. The proportion of the thickest—and deadliest—tumors stayed the same during that period. They also reported that one subtype of melanoma, known as nodular melanoma, made up a significant proportion of the thickest group of tumors. Lastly, researchers found that melanoma affected older men more commonly than any other demographic group.

What it means to you: Prevention and early detection are still key, especially for older men. Sunscreen with a sun protection factor (SPF) of at least 15 should be routinely applied to all exposed skin, with continued reapplication after sweating or swimming. One should also avoid midday sun and wear a broad-brimmed hat when outdoors. As people usually detect their own melanomas, skin self-exams, using a mirror for hard-to-see areas like the back and the soles of the feet, should be done monthly. Look for moles that are asymmetric or growing or that have irregular borders, multiple colors, or a large diameter. A dermatologist or primary care provider should examine any suspicious-looking skin changes.

Caveats: Researchers examined data from white patients only. So, while melanoma is much more common in patients with fairer skin types, one should be cautious in applying this study to the nonwhite population. Also, the investigators did not have access to data regarding patient survival.

Find out more: The National Institutes of Health has a page on melanoma, with information on diagnosis, treatment, and prevention of the disease.

The American Academy of Dermatology sponsors free skin cancer screenings throughout the country. The schedule is updated online weekly.

Read the article: Demierre, Marie-France, et al. "Early Detection of Thick Melanomas in the United States: Beware of the Nodular Subtype." Archives of Dermatology. June 2005, Vol. 141, pp. 745–750.

Abstract online: http://archderm.ama-assn.org