They also had tumors, ranging from benign, like goiters and uterine fibroids, to malignant, like those from melanoma and blood cancers. During the two-year study, four patients died of a variety of cancers.
Harriet Brown, 73, of Frederick, Md., is one of the study participants with very long telomeres. She has had benign tumors called paragangliomas in her neck and throat, thyroid cancer and two melanomas. She also has CHIP, the blood disorder associated with heart disease and blood cancers.
She has frequent scans and exams but, she said, “there is really not much I can do at this point,” because there is no way to prevent more tumors from developing.
The effects of long telomeres on people like Ms. Brown make perfect sense, said Dr. Norman Sharpless, professor of cancer policy and innovation at the University of North Carolina School of Medicine and a former director of the National Cancer Institute.
“It’s not that long telomeres make cells grow,” he said. “It’s that they don’t have the brakes to make them stop growing.” And because the telomeres of people with POT1 mutations do not grow shorter with each cell division, the cells hang around, dividing regularly. The longer they are dividing in the body, the more time they have to accumulate random mutations, some of which prompt tumor growth.
That’s especially true in blood, where cells are constantly being produced. POT1 mutations in some of these blood cells can give them time to accumulate other mutations that give them a selective advantage in growth. Soon some of these mutated blood cells pretty much take over a person’s bone marrow. The result is CHIP.
That is a new view of CHIP. The thought had been that because people with CHIP were at increased risk for blood cancer, that CHIP itself was causing cancer.
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