Is melanoma, a potentially deadly form of skin cancer, on the rise, as is often reported? Maybe not, says a new study: The melanoma epidemic may simply represent a change in how doctors are diagnosing the disease.

Anti-skin cancer campaigns have highlighted the fact that the number of melanomas has doubled in the past two decades, and continue to rise. However, some have doubted whether there are actually more cases of the cancer.

The main message is to be cautious about overstating messages about a melanoma epidemic to the public and media, study co-author Dr. Nick J. Levell from Norfolk and Norwich University Hospital, Norwich, UK, told Reuters Health in an email. Such behavior will tend to induce unnecessary anxiety and behavior that may cause distress and harm.

Dr. Levell and colleagues had a hunch that some of the epidemic was due to the fact that many cases of a skin condition known as benign melanocytic nevi - a type of mole - were now being diagnosed as malignant melanoma. So they looked at diagnoses of melanomas from 1991 and 2004 in the East Anglia region of the UK.

The rate did in fact grow, from 9.39 cases per year per 100,000 people, to 13.91, the authors report in the British Journal of Dermatology.

But it was the early-stage melanomas that accounted for much of that difference, while the rate of diagnoses of later-stage melanomas did not change.

At the same time, the researchers note, the rate of death from melanoma rose from 2.16 to 2.54 deaths per 100,000 population per year, but essentially everyone with early stage melanomas survived.

Finally, most early cases were found in parts of the body not exposed to very much sun. Such exposure, which includes ultraviolet radiation, has been tied to melanoma.

All of that suggests, the authors write, that many of the cases of melanoma now being diagnosed would have been called benign melanocytic nevi in the past.

The trend is to some degree a product of society's trend toward increasing litigation and physicians' increasing fear of making a mistake, Dr. Levell added. Neither of these is likely to be reversed. Recognition of the phenomenon does however enable the public and physicians to compensate for it to some extent.

SOURCE: British Journal of Dermatology, September 2009.