Even as the rates of other cancers are falling in the United States, the rates of melanoma — the deadliest skin cancer — are rising dramatically, most especially among young women.
That’s according to a new longitudinal study from the Mayo Clinic that spans four decades. According to researchers, the rise is most pronounced among young women.
Skin cancers are the world’s most common cancers, the World Health Organization says, with over two million cases occurring worldwide each year. These include some 132,000 cases of malignant melanoma — the most fatal of skin cancers.
Beginning in the melanocytes — or the cells that make the pigment melanin — melanoma often starts out looking like a mole. That’s when it occurs in the skin. But melanoma can also begin in other pigmented tissues like the eye or the intestines. Symptoms include changes in an existing mole or the development of an unusual growth on your skin (or eye).
This year, about 76,250 people in the U.S. will be diagnosed with melanoma and about 9,200 are expected to die from it, the American Cancer Society says. In the United Kingdom, around 60,000 people are diagnosed every year, and 15,000 are expected to die. Worldwide, about 53,000 people are killed by the deadly skin cancer, WHO says — and warns that Caucasians and other people with fairer skin are at a higher risk.
It’s been a rare cancer for a long time, but melanoma is slowly emerging as one of the most frequently diagnosed forms of cancer in the U.S., the Food and Drug Administation warns. Skin cancers have also been known to occur mostly in people 50 years and older — but the new Mayo Clinic study shows that the rates are rising dramatically among young women. The findings are published in the April issue of the journal Mayo Clinic Proceedings.
For their study, the researchers pored over health records dating back to the 1970s taken from the Rochester Epidemiology Project, a decades-long database of all patient care in Olmsted County, Minnesota. They then looked for first-time diagnoses of melanoma in patients 18-39 years old from 1970 to 2009.
What did they find?
• The number of melanoma cases in young adults increased more than sixfold in the past 40 years.
• In young women, the number of cases increased more than eightfold.
• In young men, the increase was fourfold.
“We anticipated we’d find rising rates — as other studies are suggesting — but we found an even higher incidence than the National Cancer Institute had reported,” says lead investigator Dr. Jerry Brewer, a Mayo Clinic dermatologist. “In particular, (we saw) a dramatic rise in women in their 20s and 30s,” he adds. The authors also note that Olmsted County is populated mostly by whites.
To be precise, these are the study figures:
• 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.
• Over the four decades, the incidence rate per 100,000 residents rose from 4.8 in 1970-1979 to 30.8 in 2000-2009.
• In absolute numbers, there were 16 diagnoses in 1970-1979, 44 in the 1980s, 67 in the 1990s, and 129 in 2000-2009.
• 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 eight percent reduction in the risk of death from any cause. This is significant at P=0.005.
• And each one-year increase in calendar year of diagnosis was also associated with a 9 percent decreased risk of death from metastatic melanoma. This is significant at P=0.01.