Study Suggests Melanoma May Be Overdiagnosed
But critics say early detection is best way to fight the disease
WEDNESDAY, Aug. 3, 2005 (HealthDay News) -- New research suggests that the reported rise in melanoma rates in the United States is due to overdiagnosis, and not actual new cases of the disease.
This conclusion, in turn, indicates the need to do larger trials to determine the usefulness of what appears to be increased efforts to catch the disease in its earliest stages, the study authors said.
"We really need to ask some hard questions about the utility of looking for melanoma," said study author Dr. H. Gilbert Welch, a researcher at the Department of Veterans Affairs in White River Junction, Vt. "No one's ever proven that it helps people. I'd hope we would start thinking of doing a randomized trial."
Clinicians, however, object to some of the study's implications.
"Overdiagnosis is a dangerous term because it implies that these are needlessly being diagnosed," said Dr. Elizabeth K. Hale, an assistant professor of dermatology at New York University School of Medicine in New York City. "Melanoma is a type of cancer, when it's caught early, it's considered completely curable. But if it's not biopsied and is left alone to invade, that's when it becomes life-threatening."
"It's an observational study, which is the worst way to come to a conclusion," said Dr. Vijay Trisal, an assistant professor of surgical oncology at City of Hope Cancer Center in Duarte, Calif. "Obviously, part of the increase in the rate of melanoma is that we're doing diagnosis earlier, and that is the only treatment we have right now that is really effective. As soon as the disease goes to lymph nodes it is a 50/50 chance of survival whatever you do."
"It is irrational and illogical to believe that leaving melanoma there is going to be OK," he added.
Dr. George W. Elgart, a professor of dermatology at the University of Miami School of Medicine, acknowledged that melanoma diagnosis has gone up tremendously in recent decades, and some of this may be due to hypervigilance. But, he added, "It's not such an easy thing to diagnose melanoma. Some are clearly malignant, and some are clearly benign, and some are in between. [The study authors] are statistics people. A patient isn't a study. You have to try and maximize the benefit to that patient. I would say the circumstances and risk almost force people to overdiagnose."
The new study appears online Aug. 4 in the British Medical Journal.
It has been widely reported that the incidence of melanoma in the United States is rising faster than any other major cancer. According to the study authors, the incidence in 2002 was about six times that in 1950, although some dermatologists suspect that this rise may reflect more skin biopsies, not more disease.
The American Academy of Dermatology also reports that one in 62 Americans now has a lifetime risk of developing melanoma, a 2,000 percent increase from 1930.
Melanoma, a type of skin cancer, is a particularly virulent disease. While very early cases can be treated with simple surgery, once the tumor has spread, the chances of recovery are much slimmer.
There has been some question as to whether the rise in melanoma rates is really due to more skin biopsies being conducted, rather than "true occurrence," the study authors noted.
"As you start to look hard for early forms of cancer, all of a sudden you recognize that a whole bunch more people have it than ever thought possible," Welch explained. "In a number of cancers, there may be so-called pseudodisease, abnormalities that meet the pathologic definition but that will never bother the patient."
"It's just like the space shuttle," Welch added. "Just because now they took so many pictures of it, they realize there are more small things wrong with the tile. The same is true of cancer. If we look at a population harder, we find a whole bunch more abnormalities."
But all those "things wrong" may not translate into real trouble down the line, Welch said.
To clarify the bigger picture, Welch and his colleagues examined data from Medicare to see if changes in biopsy rates corresponded to the incidence of melanoma during the period 1986 to 2001 in nine geographical areas of the United States.
In that timeframe, the average number of biopsies performed in this older population (age 65 and over) increased by a factor of 2.5. The average incidence of melanoma also increased 2.4-fold.
Most of the extra cases were early stage, yet the overall death rate from melanoma stayed stable.
Assuming that the occurrence of actual disease remained the same, then 1,000 additional biopsies were performed, resulting in 6.9 extra melanoma cases diagnosed.
"We've found 2.5 times as many people have it than we found 15 years ago, and yet mortality is no different," Welch said. "This raises questions of whether that effort really helps or if we're just telling more people they have early forms of melanoma."
"It all becomes, 'What is melanoma?' We think it's unlikely that these melanomas will kill people," he added.
The question then arises as to whether this new information matters, he said.
"To be fair, the impact of overdiagnosis in melanoma is less severe than in prostate or breast cancer, both of which involve fairly major surgery and/or chemotherapy," Welch acknowledged.
There are other issues to consider with the extra melanoma diagnoses, he said.
"There really are three burdens that are worth talking about," Welch said. "One is the psychological burden of being given a cancer diagnosis. You can't underestimate that. Second is the burden of increased surveillance. That involves real time and resources. Finally, there is more extensive surgery going on. It's not major intra-abdominal surgery but, as these excisions get wider, they can be more problematic."
But again, people working every day with patients quibble with some of these assumptions.
"It's definitely important that people have heightened awareness and don't take the wrong message home from this type of study," Hale said. "There's no great cure once melanoma has metastasized. The key is to diagnose it while it's still early and completely curable."
The American Academy of Dermatology has more on melanoma.