As one who has been aware of melanoma since the early 1980s, I find it extremely discouraging that between then and now the incidence of this disease has increased in the United States more than that of any other cancer. In 2010 it was predicted that by 2015, one in 50 patients in the US would be diagnosed with melanoma. That number was reached last year.
More new cases of skin cancer are diagnosed in the US each year than new cases of breast, prostate, lung, and colon cancer combined. According to the US Environmental Protection Agency (EPA), one in five Americans will develop some form of skin cancer in their lifetime. While melanoma accounts for only about 3 percent of all skin cancer cases, it causes more than 75 percent of skin cancer deaths.
"No one need die of melanoma," a dermatologist told me in the early 1980s. Today, one American dies from skin cancer every hour. Melanoma is now one of the most common cancers among adolescents and young adults ages 15 to 29. Exposure to ultraviolet (UV) light and sunburns, particularly during childhood, are by far the most common risk factors for the disease -- and also the most preventable.
New and improved sunscreens continue to be made available, and continuous efforts are made to educate the public about the dangers of UV exposure and the simple measures that can be taken to reduce risk. I am sure they have done some good, but not enough.
The tanning bed business continues to thrive, and people -- especially the young -- continue to flock to the beach and sunbathe in pursuit of a "healthy" tan.
Of course, other factors, such as family history and immune system deficiencies, are known risk factors for melanoma. According to the American Society for Clinical Oncology (ASCO), about 10 percent of people with melanoma have a family history of the disease. That is more than enough to warrant the recommendation that close relatives of a person with melanoma routinely have their skin examined.
Changes in two genes, CDKN2A and CDK4, have been identified as likely involved in the etiology of melanoma. The American Cancer Society suggests that people who have a strong family history of melanoma "talk to a cancer genetic counselor or a doctor who knows about cancer genetics to discuss the pros and cons of genetic testing." But, according to ASCO, only a small number of families with melanoma have changes in these genes. Thus, it is likely that other genes and environmental factors also affect risk.
One of the biggest environmental factors, one which has played a major role in UV exposure, is depletion of the ozone layer, diminishing its ability to protect life on Earth from harmful levels of UV rays. To save the ozone layer, the international community signed the Montreal Protocol on Substances that Deplete the Ozone Layer, which went into effect in 1989.
The treaty, signed by the US, called for phasing out production and consumption of ozone-depleting substances. The good news is that this global effort has been successful, according to a report issued jointly in 2010 by the World Meteorological Organization (WMO) and United Nations Environment Program. Global ozone is no longer decreasing, said Len Barrie, WMO research department director. "But it is not yet increasing."
Nevertheless, the report says the Montreal Protocol has direct benefits for public health. Without the treaty, ozone-depleting substances had the potential to increase tenfold by 2050. That might have led to up to 20 million more cases of skin cancer (and 130 million more cases of cataracts). Instead, according to the EPA, by the year 2165, "actions to protect and restore the ozone layer will save an estimated 6.3 million US lives that would have otherwise been lost to skin cancer."
Meanwhile, melanoma incidence continues to rise despite numerous well-publicized efforts to raise awareness. Fortunately, new therapies, including drugs that attack gene changes in melanoma cells, are being studied. Drugs that target the BRAF gene, which undergoes changes in the cells of about half of all melanomas, are being developed, and one such agent, vemurafenib, is already in use. Drugs that block the MEK gene, in the same signaling pathway as BRAF, have been shown to induce some melanomas with BRAF mutations to shrink. One approach now being studied is to combine a BRAF drug with a MEK drug. Clinical trials are also investigating drugs that target c-kit. And drugs that target other abnormal genes or proteins are also being studied in clinical trials.
Yes, no one need die of melanoma. But it will take more than awareness to achieve that goal.