"Because non-melanoma skin cancers generally occur in persons after 50, very little attention has been paid to their incidence in younger adults and children," says Leslie Christenson, M.D., Mayo Clinic dermatologist and lead investigator of the study. "We have discovered that these cancers are becoming increasingly prevalent in younger people, and if steps are not taken at a young age to prevent these cancers, we may see an exponential increase in the overall occurrence of non-melanoma skin cancers."
Skin cancer is the most common form of cancer diagnosed today, with approximately 1 million new cases each year in the United States. Of the two major categories of skin cancer, melanoma and non-melanoma, the latter is far more prevalent. There are two common types of non-melanoma skin cancer, basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), the types evaluated in this study.
Mayo Clinic investigators found that the incidence of BCC tumors increased over time (i.e., more occurrences in the early 2000s than in the late 1970s), as well as with the age of the patient, doubling during the study period. While the general increase in tumors in relation to age was anticipated, the overall incidence increase over time was unusual, and can be attributed mainly to the exponential increase in BCC tumors in women, especially those in their late 30s. Men often had larger BCC tumors than women - probably because women are more likely to seek early medical attention. SCC diagnoses also significantly increased over time for both men and women (incidence quadrupled), with an especially large peak in incidence of these tumors in men in their late 30s.
Dr. Christenson and her co-investigators are concerned about these findings, and foresee increasing problems with non-melanoma skin cancers for this population as they continue to age. They say that long-term or intense exposure to the sun and use of tanning beds are probably the largest causes of this increase, but also cite increased exposure to UV light, ozone depletion and increased detection as contributors. Dr. Christenson recommends beginning prevention activities at an early age - such as limiting sun exposure and always using sunscreen - to halt the increasing incidence of these cancers. And for those who have a history of excess exposure, a visit to their dermatologist to examine any unusual spots or bumps.
The study population of 485 patients was drawn from comprehensive medical records that are part of the Rochester Epidemiology project, identifying individuals younger than 40 with one or more incidents of basal cell or squamous cell carcinoma diagnosed between 1976 and 2003. All tumor tissue samples were evaluated by a dermatopathologist unaware of initial diagnoses or patient outcomes, to ensure non-biased classification of the carcinomas.
In addition to Dr. Christenson, members of the Mayo Clinic research team included Theresa Borrowman, M.D.; Celine Vachon, Ph.D.; Megha Tollefson, M.D.; Clark Otley, M.D.; Amy Weaver; and Randall Roenigk, M.D. This study was funded by the Mayo Clinic Department of Dermatology.
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