The increase in rates of melanoma, the most dangerous type of skin cancer, in the United States in recent years may reflect heightened diagnostic scrutiny rather than a true increase in new cases, the results of a study suggest.

Dr. H. Gilbert Welch, at Dartmouth Medical School in Hanover, New Hampshire, and colleagues based their conclusion on a review Medicare claims data for patients 65 years of age or older who participated in the US National Cancer Institute’s Surveillance Epidemiology and End Results (SEER) program from 1986 to 2001.

The incidence of melanoma showed a “steady, striking increase” over time, the authors note in their report, published in BMJ Online First. The average biopsy rate increased 2.5-fold, while the incidence of melanoma increased 2.4-fold.

Analyses by disease stage showed that the increase was restricted to early-stage disease, whereas the incidence of regional and distant disease spread did not change substantively. Melanoma mortality rates remained stable.

“The combination of a big increase in early disease with little change in advanced disease and little change in mortality argues that overdiagnosis is going on,” although that’s not to say that “there hasn’t been some increase in true disease,” Welch told Reuters Health.

The authors acknowledge that an alternative explanation for their findings is that earlier treatment or better therapy in the face of increased incidence could be reflected in stable mortality, but this “seems implausible,” they add. Otherwise, disease rates would not track so closely with biopsy rate.

Dr. Rhoda Narins, professor of dermatology at New York University School of Medicine and president of the American Society for Dermatologic Surgery, does not agree “that it’s an issue of overdiagnosis. I think we’re finding more melanomas early and treating them,” Narins report.

“The criteria for diagnosing it have changed and I think people are coming in sooner,” she said. “Pathologists have become more sensitive and things that they might have read as dysplastic nevi in the past, they are reading as early melanoma now.”

Either way, she added, “I think if there’s any question in the doctor’s mind about whether a lesion is a melanoma he or she should remove it rather than watch something like that, because it can be a deadly disease and it is a life-saving procedure.”

Welch agreed that suspicious lesions should be removed. But “we should separate out the question of whether people who have concerning lesions should go to their doctor versus the question of whether we should invite everybody in for mass skin screening, regardless of whether anything is bothering them,” he said.

Overdiagnosing benign lesions is potentially harmful because of the psychological burden it places on people who are wrongly diagnosed with cancer, he said, plus the more intensive follow-up that is required.

“Even though the surgery is simple, in the case of a melanoma diagnosis usually it is bigger than it would be otherwise,” he added. “Surgeons take a wider margin, and in certain parts of the body that can get complicated, if it’s on the face or near the buttocks, for example.”

SOURCE: British Medical Journal, August 4, 2005.