Men are more likely than women to be diagnosed with malignant melanoma after the age of 40, a UC Irvine College of Medicine study has found.
The study is the first to show a specific way in which gender plays a role in the rate and age at which men and women may get skin cancer. It suggests that women who are going through menopause are at least temporarily able to reduce the rate at which they contract the disease. The findings were presented today at the Society for Investigative Dermatology's annual meeting in Washington, D.C.
Malignant melanoma is the most deadly of all skin cancers. While it constitutes less than 10 percent of all skin cancers, its rate is increasing faster than any other cancer in the world, according to the National Cancer Institute. The number of new melanoma cases has doubled in the past 20 years, and the disease kills more than 7,000 people every year in the United States. Its cause is not well understood.
Frederick Beddingfield, a UCLA resident and Rand Graduate School doctoral fellow serving a cancer research fellowship at UCI, Hoda Anton-Culver, UCI professor of epidemiology, and their colleagues analyzed more than 40,000 patient records from California cancer registries and more than 100,000 cases nationwide. They found that women appeared to contract melanoma at a slightly higher rate than men until age 40. The rate for women aged 45 to 60 leveled off, while the rate for men rose dramatically after age 40.
Not only did older men have a much higher rate of melanoma, the melanomas they developed were of a much later stage on average. Furthermore, the researchers found that the overall rate of melanoma has been increasing rapidly over the last 25 years. The rate of increase in melanoma for all ages was about 4.6 percent a year for men, and 3.2 percent a year for women.
"This is the first study we know of that shows these specific and different patterns of contracting melanoma between women and men," Beddingfield said. "This difference may be due to hormonal or other changes during menopause, but the cause of the disparity is still unknown. Because melanoma is almost uniformly survivable when detected early but has a much worse prognosis if detected late, there may be a role for public education campaigns and screening. Elderly men appear to be prime candidates for such interventions. Also, by exploring this apparent protected period in women during menopause, we may be able to prevent this disease from occurring."
"Melanoma rates increase in both sexes with increasing age, and that rate accelerates as both men and women enter middle age," Anton-Culver said. "However, it seems that women going through menopause have some kind of protective effect, which keeps their rate from increasing, at least until age 60."
In addition to finding the sex differences in melanoma, the researchers also found that the risks of dying from melanoma were raised by increasing age, having thicker tumors or having the tumors on the torso instead of the arms, legs, head or neck. Having nodular tumors instead of other types of melanomas also increased the risk of dying from the disease.
The researchers now are looking at what may cause this plateau effect among women of menopausal age. The study is part of the UCI-UCSD Cancer Genetics Network Center, which was established through a grant from NCI to study the complex genetic interactions in cancer. Under the direction of Anton-Culver, the center at UCI is one of eight research institutions nationwide that make up the Cancer Genetics Network, which was established in 1998 by NCI. Beddingfield has received grant support for his research fellowship from the Dermatology Foundation.
Beddingfield and Anton-Culver's colleagues in the study included Stephanie Litwack, Argyrios Ziogas and Thomas Taylor, all of UCI.