About 6 percent of patients will develop a second melanoma within one year of the initial diagnosis, while 8 percent will be diagnosed with a second malignancy within two years, according to the researchers from Dartmouth Medical School in Hanover, N.H.
"This is not surprising, but it gives us another stimulus to be very vigilant about picking up second and third melanomas," said Dr. Vijay Trisal, assistant professor of surgical oncology at City of Hope Cancer Center, in Duarte, Calif. "Once it goes to the lymph nodes, we basically have no treatment." Trisal was not involved with the study.
Melanoma is a particularly virulent form of skin cancer. It begins in cells known as melanocytes, the pigment-producing cells that give skin its color, but can spread quickly and unpredictably to other organs of the body.
According to the new study, previous studies have put melanoma recurrence at less than 4 percent within one year.
Six percent of the participants developed an additional melanoma within one year of the first diagnosis, while 8 percent developed an additional melanoma within two years.
Roughly two-thirds of those who developed additional malignancies and 37 percent of those who did not had at least one atypical mole, which is a risk factor for additional melanomas. Someone with three or more atypical moles had four times the risk of developing an additional tumor. Atypical moles have at least three of the following features -- a diameter larger than 5 millimeters; redness; an irregular or ill-defined border; a variety of colors or a portion that is flat, the researchers said.
In one-third of the patients who developed another melanoma within two years, the subsequent melanoma was deeper than the first.
The study found little relationship between risk and benign moles, eye and hair color, or length of sun exposure. There was, however, a surprising inverse relationship between blistering sunburn and melanoma -- those with a history of sunburn were less likely to develop a second melanoma than those without, the researchers wrote. But this finding "must be viewed cautiously," the researchers said. It's possible that people who are predisposed to multiple melanomas may be less vulnerable to sunburn than those who get only one melanoma, or there may be a separate reason for the finding, the researchers said.
Another study in the same issue of the journal reported that nearly half of high schools surveyed in the Denver area contained advertisements for tanning parlors in their newspapers.
The ultraviolet (UV) radiation used in tanning parlors is a known carcinogen. The authors of the study, led by Dr. Scott Freeman, of the University of Colorado at Denver and Health Sciences Center, called for cancer-prevention policies that prohibited UV tanning advertising to minors.
The increasing incidence of melanoma in the United States also prompted the journal to publish an editorial calling for a national, five-year plan for "enhancing prevention and early detection for melanoma." The plan, the editorial stated, should start with a randomized trial of melanoma screening in white men aged 50 and over, who have the highest rates of the disease. The editorial also discussed the possibility of providing better insurance coverage -- including Medicare and Medicaid -- for such screening.
For individuals who have been diagnosed with melanoma, Trisal suggested surveillance every six months from a dermatologist. People who have been diagnosed with a second melanoma should consider getting checked every four months.
Nouri said, "Depending on the thickness of the melanoma, they should be seen every two to six months for the first two to three years to make sure there is no recurrence."
By Amanda Gardner, HealthDay News, April 17, 2006