By Amanda Gardner
Doctors have long known that people who survive one melanoma have a markedly higher risk of developing another of these aggressive skin cancers. Now, for the first time, a study has found that survivors of non-skin cancers also may have an increased risk of melanoma.
The risk was most pronounced among survivors of breast cancer, prostate cancer, lymphoma, and leukemia. Women who developed breast cancer before age 45 and recovered, for instance, were 38 percent more likely than women in the general population to develop melanoma later in life.
Excessive exposure to UV radiation from sunlight (or tanning lamps) is the biggest risk factor for melanoma. The apparent link between melanoma and other cancers, however, may be explained in part by an underlying genetic susceptibility to multiple types of cancer, the researchers say.
People who have had a non-melanoma cancer should be especially vigilant about avoiding sun damage and checking their skin for moles, says senior author Jeremy S. Bordeaux, M.D., director of the melanoma program at University Hospitals Case Medical Center and Case Western Reserve University, in Cleveland.
"If they notice a new dark spot or a changing dark spot, they need to have that looked at by a dermatologist," Bordeaux says. And if they haven't already, he says, cancer survivors may want to see a dermatologist to get a baseline checkup. (Melanoma survivors should already have a set schedule with their skin doctor.)
Using a nationwide registry maintained by the National Cancer Institute, Bordeaux and his colleagues analyzed data from 70,819 people whose first cancer was melanoma and 6,353 who received a melanoma diagnosis after a previous cancer. Their findings appear this week in the Archives of Dermatology.
As expected, melanoma survivors were up to 12 times more likely than people in the U.S. population as a whole to receive a melanoma diagnosis (a second one, in their case).
The melanoma risk associated with several other cancers was much lower, yet still notable. Compared to the general population, prostate-cancer survivors had a 58 percent higher risk and lymphoma survivors had a 79 percent higher risk if they received their first cancer diagnosis before age 45.
Across the board, younger cancer survivors were more likely than people initially diagnosed after age 45 to develop melanoma down the road, perhaps because cancers that develop early in life are more likely to have a genetic basis, the study notes.
In the older age group, the risk of melanoma was elevated by 40 percent among survivors of thyroid cancer, 34 percent among lymphoma survivors, and 79 percent among leukemia survivors. Women who'd had breast cancer had a 12 percent higher risk.
Melanoma risk was just 8 percent higher in men who'd had prostate cancer after age 45, but that's not negligible because so many men will develop the cancer during their lifetime, Bordeaux says. "Even though the risk was kind of small, the incidence [of prostate cancer] is so high it would affect a lot of people."
The warning signs of melanoma include moles or dark spots larger than a pencil eraser and spots that are asymmetrical or unevenly colored. Regardless of their cancer history, people are at increased risk of melanoma if they have fair skin or a lot of moles, or if they've spent a lot of time in the sun.
"If melanoma is caught early, it's 100 percent curable," Bordeaux says. "But once it's more advanced and spreads to other parts of body, it's one of -- if not the -- most aggressive cancers and can be very, very fatal."