A study, published in Nature Medicine, reports that at least 2% of people over age 40 and 5% of people over 70 have mutations linked to leukemia and lymphoma in their blood cells.

As known to us, mutations in the body’s 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 don’t have the blood cancers.

The researchers found that mutations in the blood would be associated with changes in stem cells that develop into blood cell, via zeroing in on such genetic mutations that were present in the blood but not in tumor samples from the same patients.

Many older people have mutations linked to leukemia. In 341 patients ages 40-49, fewer than 1% had mutations in 19 leukemia- or lymphoma-related genes. But among 475 people ages 70-79, over 5% did. And over 6% of the 132 people ages 80-89 had mutations in these genes.

The current study likely underestimates the percentage of people with mutations in leukemia and lymphoma genes because the researchers only were able to identify small mutations, not large structural variations or the insertions and deletions of chunks of genetic material.

Still, it would be premature for people to undergo genetic testing to see if they have mutations linked to leukemia and lymphoma as a means to predict their risk of blood cancers.

Reference:

Age-related mutations associated with clonal hematopoietic expansion and malignancies. Nature Medicine, 2014