Nonmelanoma Skin Cancer Ups Risk for Other Cancers

By Steven Reinberg
27 aug 2008 -- People with a history of nonmelanoma skin cancer face twice the risk of developing other malignancies, a new study finds.
Every year in the United States, about 1 million people are diagnosed with nonmelanoma skin cancers, according to the American Cancer Society. Developing these tumors is known to increase the risk for melanoma, the most serious form of skin cancer. But the link between skin cancer and cancers at other body sites is just beginning to be explored.
Now, researchers reporting online Aug. 26 in the Journal of the National Cancer Institute say that a history of nonmelanoma lesions doubles the odds for a subsequent cancer. "That's not just cancer related to melanoma or other skin cancers," noted lead researcher Anthony Alberg, from the Medical University of South Carolina.
In this study, the increased risk was seen for lung cancer, colon and breast cancer, Alberg said. "For prostate cancer, the trend was in the direction of increased risk, but the association was weaker and not statistically significant," he said.
Alberg believes the increased risk may be due to a weakened ability to repair DNA damage to cells. "People who have suboptimal ability to repair DNA damage that the sun can cause are far more likely to get nonmelanoma skin cancer. We are hypothesizing that that might also be the link to why there is a greater increased cancer risk in general," he said.
For the study, Alberg's team looked at the risk of developing cancer among 769 people with a history of nonmelanoma skin cancer. The researchers compared these people to 18,405 people with no history of skin cancer.
Over 16 years of follow-up, the researchers found that the incidence of cancers was 293.5 per 10,000 person-years among people with a history of skin cancer, compared to 77.8 per 10,000 among people without a history of the disease.
In addition, the younger a person got a nonmelanoma skin cancer, the higher his or her risk of developing other cancers, Alberg said.
Dr. Robin Ashinoff, a dermatologist at New York University Medical Center, New York City, agreed that the inability to repair DNA damage associated with nonmelanoma skin cancer may make developing other cancers more likely.
"It is not unreasonable to suppose that patients with nonmelanoma skin cancers, especially if diagnosed when the patient is young, puts that person in a higher risk category of systemic cancers," Ashinoff said.
People who develop skin cancers may have inherited a family tendency for other cancers because of inadequate ability to repair DNA, Ashinoff said. "In addition, these patients are followed closely for further skin cancers, and therefore may have an increased diagnosis of other cancers, because they are plugged into the medical system," she noted.
"Our skin cancer patients should know that they may be at increased for a wide variety of cancers like breast, lung and colon, and should not ignore early signs and symptoms if they occur," Ashinoff advised.
Dr. Martin Weinstock, chair of the skin cancer advisory committee at the American Cancer Society, said awareness and testing are key.
"People who have had skin cancers should make sure they are up-to-date on all their screening tests," Weinstock said. "They should be up-to-date on their colonoscopies, fecal occult blood and mammograms and Pap smears," he said.
In addition, people need to protect themselves from UV exposure, so they don't develop skin cancer in the first place, Weinstock said.
In another report, published in the same issue of the journal, researchers found that patients who use blood pressure-lowering drugs called angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) have a lower risk of developing basal or squamous cell skin cancers.
In research led by Jennifer Christian, from the VA Medical Center and Brown University in Providence, R.I., researchers found that patients taking ACE inhibitors or ARBs had a 39 percent lower risk of developing basal cell skin cancer and a 33 percent lower risk of developing squamous cell skin cancer.
Why these drugs lower the risk of skin cancer isn't known, the researchers said.