People with the most common kind of skin cancer could face future cancer risks down the road, especially those diagnosed with the skin cancer before age 25, a new study suggests.
Researchers from the University of Melbourne and University of Oxford found that people who were diagnosed with non-melanoma skin cancer have a 1.36 times higher relative risk for another malignant cancer, compared with people who have no history of non-melanoma skin cancer.
And people who had had non-melanoma skin cancer had a significantly higher relative risk of salivary gland, bone and upper gastrointestinal tract cancers, as well as melanoma, according to the Cancer, Epidemiology, Biomarkers & Prevention study.
However, people who were diagnosed with non-melanoma skin cancer when they were younger than age 25 had a 23 times higher risk of developing another cancer. Their risks of developing salivary gland cancer and melanoma were especially high -- 93 times higher risk for salivary gland cancer and 94 times higher risk for melanoma -- though they also faced higher risks of bone cancer (53 times higher risk), blood cancers (26 times higher risk) and brain cancer (20 times higher risk).
"Early detection of cancers through screening of asymptomatic people works best when screening can be targeted at those at greatest risk," study researcher Dr. Rodney Sinclair, M.B.B.S., M.D., the director of dermatology at the Epworth Hospital and professor of medicine at the University of Melbourne, said in a statement. "Our study identifies people who receive a diagnosis of NMSC [non-melanoma skin cancer] at a young age as being at increased risk for cancer and, therefore, as a group who could benefit from screening for internal malignancy."
The study is based on data from 502,490 people with a history of non-melanoma skin cancer and 8,787,513 people with no history of the cancer, who were followed up with after five to six years. At the end of the follow-up period, 67,148 people who had a history of non-melanoma skin cancer had developed another cancer, compared with 863,441 people without a history of non-melanoma skin cancer.
Generally, the risk of developing another cancer was less dramatic as age of diagnosis increased. For example, someone who was diagnosed with non-melanoma skin cancer before age 25 had a 23 times higher risk of developing cancer, while someone who was diagnosed with non-melanoma skin cancer between ages 45 and 59 only had a 1.74 times increased risk.
One weakness researchers noted about the study was that they were unable to distinguish between squamous cell carcinomas (SCCs) and basal cell carcinomas (BCCs); "it might be that one type of NMSC [non-melanoma skin cancer] is more strongly associated with increased risks of subsequent primaries; however, only subtle differences have been noted in studies that do differentiate SCCs and BCCs," they wrote in the study.