July 7, 2010 -- Aging cells greatly increase your risk of deadly cancer -- even if you're still relatively young.
Cells stay young as long as they can repair their own DNA. That's up to telomeres, the proteins at the end of each chromosome. But every time a cell reproduces, its telomeres get shorter.
A few aging cells isn't much of a problem. But a startling new study now shows that people who accumulate a lot of cells with short telomeres have greatly increased risk of fatal cancers.
Compared to people at the top third of average telomere length, those at the bottom third have a threefold higher risk of cancer. Those in the middle third have twice the cancer risk as those with the longest telomeres.
"Of note, telomere length was preferentially associated with individual cancers characterized by a high fatality rate such as gastric, lung, and ovarian cancer -- but less so with tumors linked to better prognosis," find Peter Willeit, MD, of Austria's Innsbruck Medical University, and colleagues.
Those in the lowest third of telomere length were over 11 times more likely to die of cancer than those in the highest third. Those in the middle third were 5.6 times more likely to die of cancer.
For 10 years, Willeit's team followed 787 residents of Bruneck, Italy, who received all their medical care at the same local hospital. Ranging in age from 40 to 79, all were cancer free at the beginning of the study. A decade later, 92 of the study participants had developed cancer.
At regular intervals, the researchers calculated the average telomere length of each participant's white blood cells. This led to a number of interesting findings:
- Men had shorter telomeres than women.
- Short telomere length was linked to risk of diabetes, chronic infection, and less physical activity.
- Short telomere length was linked to increased risk of bladder, lung, kidney, and head-and-neck cancer, as well as to non-Hodgkin's lymphoma.
- Short telomere length was not linked to breast or colon cancer.
What's going on? Willeit and colleagues calculate that short telomere length gives a person the cancer risk of a much older individual. They suggest that short telomere length indicates an aging immune system.
Moreover, they suggest that cells with short telomere length may reactivate the enzyme telomerase in a desperate attempt to restore telomere length. In doing so, these cells may accidentally transform themselves into tumor cells.
The Willeit study appears in the July 7 issue of the Journal of the American Medical Association.