Semantics of 'epidemic' irrelevant

June 1, 2006

Initial melanomas discovered by dermatologists were more likely tobe thin (0.75 mm or less) compared with malignancies found by otherphysicians.

Darrell S. Rigel, M.D., reports evidence demonstrating that the number of new melanoma cases seen each year has been increasing at a rapid rate in the United States and other countries throughout the world, and that the increase in incidence is real and not an artifact associated with loosened histological criteria, increases in screening or awareness or improvements in counting methods.

"With regard to incidence, there is a clear increase in the number of cases of melanoma being diagnosed compared with prior periods, and that fulfills the medical definition of an epidemic. However, we are scientists and clinicians, not English majors, and what we really care about are the implications for our patients rather than semantics. For dermatologists, the take-home message on this issue remains that we need more public education to promote behavioral changes that can reduce risk as well as to enhance early diagnosis by patients and physicians. Hopefully, if we do our job, current alarming projections on lifetime risk will be totally wrong," says Dr. Rigel, clinical professor of dermatology, New York University School of Medicine, New York.

"In some ways it seems we are turning the corner on melanoma. However, the number of melanomas diagnosed continues to rise and without question, melanoma remains a serious threat," says Dr. Cornelison, professor and chairman of dermatology, Oklahoma University Health Sciences Center, Oklahoma City.

Considering the facts

Statistics from the National Cancer Institute (NCI) Surveillance Epidemiology and End Results (SEER) program in the United States clearly show there has been a marked increase in the number of cases of melanoma and lifetime risk over the past two decades, Dr. Rigel says.

In 1982, it was estimated that Americans had a 1 in 250 lifetime risk of getting an invasive melanoma. That risk rose to 1 in 150 by 1985, much faster than projected, and currently it is estimated that 1 in 60 Americans will develop an invasive melanoma in their lifetimes.

An increase in melanoma incidence is not a phenomenon limited to white Americans. Studies from Canada, various countries in western Europe as well as from Australia and New Zealand also show rapidly rising incidence rates, and there are reports demonstrating increases in melanoma among Hispanics and blacks in the United States and Asians in Japan.

"These data show clearly that melanoma has continued to grow significantly as a public health problem," Dr. Rigel says.

Further evidence of an increasing incidence rate is derived from the observation that while the incidence rate has been rising exponentially over the past 10 years, the mortality rate has remained flat and the survival rate has been increasing.

"Mathematically, the only explanation for that combination of events is that the incidence is rising at an even faster rate than the survival rate," Dr. Rigel says.

Dismissing potential bias

Data from a variety of sources support the concepts that the rising incidence is real and cannot be explained by increased screening, awareness or diagnosis of thinner lesions, Dr. Rigel notes.