A new reason to wear sunscreen.

People with a history of nonmelanoma skin cancer face twice the risk of developing other malignancies — including lung, colon and breast cancers, according to a new study published in the Journal of the National Cancer Institute.

The American Cancer Society estimates that about 62,480 new melanomas will be diagnosed in 2008 in the United States. Previous studies have documented that people who have had nonmelanoma skin cancer were at increased risk for developing melanoma, the deadliest form of skin cancer. But it was less known whether they were also at risk for cancers that did not involve the skin.

Now, in the first study to ever investigate the relationship between nonmelanoma skin cancer and cancers in other organs, researchers have found that a history of nonmelanoma lesions doubles the odds for a subsequent cancer, including lung, colon and breast cancer.

The recent study published was conducted by Anthony Alberg, PhD, of the Medical University of South Carolina and his colleagues. Beginning in 1989, they compared the risk of malignancies in 769 individuals who were diagnosed with nonmelanoma skin cancer and 18,405 individuals with no history of the disease. They followed the participants for 16 years.

The overall rate of cancer diagnosis was 293.5 cases per 10,000 person-years in the nonmelanoma skin cancer group, and 77.8 per 10,000 in the group that had no history of the disease.

The researchers accounted for other known cancer risk factors such as age, sex, body mass index (BMI), smoking status and educational level. Lead researcher Dr. Alberg told HealthDay that he 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.

The increased risk for subsequent cancer was unaffected by the removal of melanoma. The figures were the same for both types of nonmalignant cancers, basal cell and squamous cell carcinoma. The strongest association between a history of skin cancer and subsequent malignancies was seen in the youngest study participants, aged 25 to 44 years.

"This pattern of associations, with earlier age of [nonmelanoma skin cancer] diagnosis being linked more strongly to the risk of developing subsequent malignancies, is consistent with the pattern that one would expect for a marker of inherited predisposition to cancer," the authors wrote.

The new findings are published online in the Journal of the National Cancer Institute. Click here to read more about this study.