People who have had a normally non-fatal form of skin cancer have double the risk of developing other types of cancers, US researchers said on Tuesday, Reuters reported.
They said the increased risk is especially pronounced in younger people and suggests people who get these less serious forms of skin cancer may be more cancer-prone in general.
"It seems like non-melanoma skin cancer, even though it is a non-fatal disease, may be a warning sign for increased risk of other, more serious cancers," said Anthony Alberg, a researcher at the Medical University of South Carolina in Charleston, whose study appears in the Journal of the National Cancer Institute.
Non-melanoma skin cancers, which include basal cell carcinoma and squamous cell carcinoma, affect an estimated 1 million people each year in the United States, according to the American Cancer Society.
"It is far and away the most common form of cancer," Alberg said in a telephone interview. But they are slow-growing and cause no harm if they are removed.
Previous studies have found that people who get these types of skin cancers are at higher risk of developing melanoma, the deadly form of skin cancer.
Alberg said his research suggests that non-melanoma skin cancer may be a risk factor for other cancers as well.
He and colleagues analyzed data from a 16-year study of people in Washington County, Maryland, that compared cancer risks among 769 people who had been diagnosed with non-melanoma skin cancer and 18,405 people who had no history of skin cancer.
"People with a personal history of non-melanoma skin cancer were two times more likely to develop a subsequent cancer compared to people without a personal history of non-melanoma skin cancer," Alberg said.
That was true even after they adjusted for age, obesity, history of smoking, level of education, skin type and sun exposure. "The differences didn't go away," Alberg said.
And people who developed skin cancer at a younger age, those 25 to 44, had 2.6 times higher risk of developing another cancer.
"The results were pretty clear in showing the earlier the age of developing non-melanoma skin cancer, the higher the increased risk for subsequent malignancies," he said.
Alberg said the findings suggest some people may have a genetic predisposition to skin cancer that may also be linked to the development of other forms of cancer.
He suspects this may have something to do with a person's ability to repair DNA in skin cells damaged by ultraviolet radiation from the sun. "If they are less adept at that, their risk for skin cancer increases," Alberg said.
While more study is needed about individual risks, Alberg said people who have had non-melanoma skin cancer would be wise to mention it to their doctor.
"It seems to be a more important part of a personal health history than we thought before," he said.