Skin Cancer Risk may be Gauged by Accumulated DNA Damage

Melanoma risk can be estimated long before the detection of any suspicious moles, stated a UC San Francisco scientist who led a new study to detect DNA mutations in individual skin cells. Melanoma is the most deadly skin cancer.

"The genomic methods used to probe skin damage in the new study could be developed to estimate baseline melanoma risk for individuals in the general population, and to make recommendations about how often someone should be screened for cancer by a dermatologist," according to senior author A. Hunter Shain, PhD, assistant professor in UCSF's Department of Dermatology. The study was published in Nature.

‘Mutation count in sun-exposed melanoma cells has the potential to offer personalized screening guidelines.’

Researchers sequenced melanocyte DNA in 6 skin samples, two melanoma survivors, and four cadavers of persons never afflicted by melanoma to tally mutations that are the main drivers of melanoma's emergence and growth.

In the former cancer patients, melanocytes from normal skin near the melanoma had more mutations, including melanoma-associated mutations, than skin from the same sites in individuals who never had melanoma.

People with many moles should still be screened, Shain said, but only 30 percent of melanomas arise from pre-existing moles.

"Melanomas really can appear out of nowhere," Shain said. "We found out in this work that normal skin contains numerous melanocytes that already exhibit some of the mutations associated with cancer. Essentially, we found the precursors to the 70 percent of melanomas that do not arise from pre-existing moles."

Childhood sunburns might increase skin cancer risk than occupational exposures during adulthood, such as working outdoors.

More mutations in melanocytes from the back and limbs than in skin from the head and neck were identified.

"We anticipate that a streamlined, automated version of these methods will one day become widely available to gauge melanoma risk and could serve as the basis for cancer-screening recommendations," Shain said.

Melanoma Facts and Figures

• Melanoma is a dangerous form of skin cancer caused mainly due to exposure to the sun's damaging UV rays.
• It commonly arises from new or pre-existing moles.
• By the end of 2020, about 100,000 people in the United States will be diagnosed with melanoma, and about 6,850 will die.
• The lifetime risk for melanoma is about 1 in 38 for whites, 1 in 1,000 for Blacks, and 1 in 167 for Hispanics.

Source: Medindia