Many Older People Have Mutations Linked to Leukemia, Lymphoma in Their Blood Cells

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Newswise At least 2 percent of people over age 40 and 5 percent of people over 70 have mutations linked to leukemia and lymphoma in their blood cells, according to new research at Washington University School of Medicine in St. Louis.

Mutations in the bodys cells randomly accumulate as part of the aging process, and most are harmless. For some people, genetic changes in blood cells can develop in genes that play roles in initiating leukemia and lymphoma even though such people dont have the blood cancers, the scientists report Oct. 19 in Nature Medicine.

The findings, based on blood samples from nearly 3,000 patients, dont mean that people with these genetic mutations are destined to develop a blood cancer. In fact, the vast majority of them wont as the incidence of blood cancers such as leukemia or lymphoma is less than 0.1 percent among the elderly.

But its quite striking how many people over age 70 have these mutations, said senior author Li Ding, PhD, of The Genome Institute at Washington University. The power of this study lies in the large number of people we screened. We dont yet know whether having one of these mutations causes a higher than normal risk of developing blood cancers. More research would be required to better understand that risk.

The researchers analyzed blood samples from people enrolled in The Cancer Genome Atlas project, a massive endeavor funded by the National Cancer Institute and the National Human Genome Research Institute at the National Institutes of Health (NIH). The effort involves cataloguing the genetic errors involved in more than 20 types of cancers.

The patients whose blood was analyzed for the current study had been diagnosed with cancer but were not known to have leukemia, lymphoma or a blood disease. They ranged in age from 10 to 90 at the time of diagnosis and had donated blood and tumor samples before starting cancer treatment. Therefore, any mutations identified by the researchers would not have been associated with chemotherapy or radiation therapy, which can damage cells DNA.

The researchers, including Genome Institute scientists Mingchao Xie, Charles Lu, PhD, and Jiayin Wang, PhD, zeroed in on mutations that were present in the blood but not in tumor samples from the same patients. Such genetic changes in the blood would be associated with changes in stem cells that develop into blood cells, but not to the same patients cancer.

They looked closely at 556 known cancer genes. In 341 patients ages 40-49, fewer than 1 percent had mutations in 19 leukemia- or lymphoma-related genes. But among 475 people ages 70-79, over 5 percent did. And over 6 percent of the 132 people ages 80-89 had mutations in these genes.

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Many Older People Have Mutations Linked to Leukemia, Lymphoma in Their Blood Cells