TUESDAY, July 6 (HealthDay News) -- People who have white blood cells with shorter telomeres may be at a higher risk of developing cancer, especially aggressive cancers that are more likely to kill, new research suggests.

Telomeres are the "shoelace ends" that cap and protect your chromosomes and naturally get shorter as you age.

Right now, the findings aren't likely to have any clinical usefulness, said Dr. Stefan Kiechl, senior author of a paper appearing in the July 7 issue of the Journal of the American Medical Association. But in the future, he added, "telomere length may well become a component of risk scores for cancer manifestation and, eventually, cancer prognosis."

The main significance of the new research is in understanding the biology of cancer, according to Dr. Eliot Rosen, an oncology professor at Georgetown Lombardi Comprehensive Cancer Center in Washington, D.C.

"If the study is confirmed, it's a very, very important finding, but there isn't enough information [here] to be certain of this," he said. "It's very interesting and potentially important, but I wouldn't make too much of it till it's confirmed."

Previous studies have linked cancer and short telomeres via an enzyme called telomerase, which builds telomeres, Rosen explained.

In the natural life cycle, cells stop dividing when telomeres become too short. Cancer cells are able to override this by expressing more of the enzyme telomerase.

"Normal adult cells in the body do not express a telomerase, so for a cell to become immortal and continue to divide, the cell has to express telomerase," Rosen explained.

"What's believed to be the major function of a telomere is to maintain the stability of chromosomes, to prevent the chromosomes from degrading or rearranging or becoming altered in one way or another," he continued. "A reduced telomere length would be predicted to lead to an increased risk of cancer."

This is the first prospective study, meaning one that follows individuals over time, to look at this question.

The authors, from England, Austria and Italy, measured telomere length in leukocytes (white blood cells) in 787 individuals who did not have cancer, before following the individuals for 10 years, until 2005, in what is known as the Bruneck Study out of South Tyrol, Italy.

Individuals who had shorter telomere length at the start of the study were more likely to develop cancer, even after adjusting for more conventional cancer risk factors, including age.

Those with the shortest telomere length had more than triple the risk of developing cancer, and those in the middle group had twice the risk compared to those with the longest telomere length.

Those in the short telomere group also had a higher risk of dying from their malignancy than those with longer telomeres.

This may be because shorter telomere length was also associated with more aggressive cancers, such as stomach, lung and ovarian.

Still, there may be a way to keep your telomeres longer.

"Telomere shortening is accelerated by inflammation and oxidative stress as induced by unhealthy lifestyles like smoking," said Kiechl, a neurology professor at Innsbruck Medical University in Austria. "There are extensive research efforts at the moment to identify conditions (like lifestyle features) that promote or counteract telomere shortening, and this knowledge should be important for future primary prevention of cancer."

More information

The University of Utah has more on telomeres.