April 2, 2012— -- More young adults -- particularly young women -- are developing melanoma, the most dangerous form of skin cancer. But the odds of surviving melanoma have improved over time, a new study found.
The study, which spanned four decades, found that the incidence of cutaneous melanoma rose by a factor of more than 6 from 1970-1979 through 2000-2009, according to Dr. Jerry Brewer and colleagues at the Mayo Clinic in Rochester, Minn.
On the other hand, the risk of dying from melanoma fell by 9 percent per year over the same period, Brewer and colleagues reported in the April issue of Mayo Clinic Proceedings.
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The findings come from data collected by the Rochester Epidemiology Project, which has been aggregating medical information on residents of Olmstead County, Minn., since 1966.
The researchers cautioned that residents of the county -- largely white and highly educated -- might not reflect the rest of the U.S. population, so the results may not apply more widely.
However, research based on the CDC's Surveillance Epidemiology and End Results (SEER) database has shown that national melanoma rates have been rising, while survival has been improving, the researchers noted.
"We anticipated we'd find rising rates, as other studies are suggesting," Brewer said in a statement. "But we found an even higher incidence than the National Cancer Institute had reported using the (SEER) database, and in particular, a dramatic rise in women in their 20s and 30s."
The analysis included 256 men and women, ages 18 to 39, with a first lifetime diagnosis of melanoma from Jan. 1, 1970, through Dec. 31, 2009, the researchers reported.
Over the four decades, he and colleagues found, the incidence rate per 100,000 residents rose from 4.8 in 1970 through 1979 to 30.8 in 2000 through 2009.
In absolute numbers, there were 16 diagnoses in 1970-1979, 44 in the 1980s, 67 in the 1990s, and 129 in 2000 through 2009, Brewer and colleagues reported.
Among men, the rate went from 4.3 per 100,000 residents to 18.6 over the four decades, slightly more than a four-fold increase.
Among women, the rate skyrocketed by a factor of more than eight, from 5.4 to 43.5 cases per 100,000 residents.
But each one-year increase in calendar year of diagnosis was associated with an 8 percent reduction in the risk of death from any cause.
And each one-year increase in calendar year of diagnosis was also associated with a 9 percent decreased risk of death from metastatic melanoma.
The researchers also found that over the years the proportion of early-stage cancers among the diagnoses rose, perhaps as a result of better awareness of the risk of skin cancer.
The researchers noted that tanning beds have been associated with increased risk of skin cancer, and Brewer said they might play a role in the increased incidence he and colleagues found.
"The rise in tanning bed behavior over the years is probably a major contributor," he said.
The researchers cautioned that the epidemiology project might have missed some cases of melanoma, if patients sought treatment elsewhere. As well, they noted, residents of the county usually have good medical care, so the result might not apply to populations with more limited access.