A distinct pattern in the changing length of blood telomeres, the protective end caps on human DNA strands, can predict cancer many years before actual diagnosis, according to a new study from Northwestern Medicine and Harvard University. The pattern, a rapid shortening followed by a stabilization three or four years before cancer is diagnosed, could ultimately yield a new biomarker to predict cancer development with a blood test. This is the first reported trajectory of telomere changes over the years in people developing cancer, according to the researchers. The opensource study is published in the journal EBioMedicine, a new cutting-edge journal from Elsevier, The Lancet and Cell Press.
The team have been trying to understand how blood cell telomeres, considered a marker of biological age, are affected in people who are developing cancer. But the results have been inconsistent with some previous studies stating they are shorter, some studies stating they are longer and some studies showing no correlation at all.
The new study shows why previous results were confusing. In the current study, the team took multiple measurements of telomeres over a 13-year period in 792 persons, 135 of whom were eventually diagnosed with different types of cancer, including prostate, skin, lung, leukemia and others.
Initially, the researchers discovered telomeres aged much faster (indicated by a more rapid loss of length) in individuals who were developing but not yet diagnosed with cancer. Telomeres in persons developing cancer looked as much as 15 years chronologically older than those of people who were not developing the disease. However, then the lab found the accelerated aging process stopped three to four years before the cancer diagnosis.
The team explain that understanding this pattern of telomere growth may mean it can be a predictive biomarker for cancer. As the data findings showed a strong relationship in the pattern across a wide variety of cancers, with the right testing these procedures could be used to eventually diagnose a wide variety of cancers.
The current study is believed to be the first to look at telomere length at more than one time point before diagnosis. That’s significant because cancer treatment can shorten telomeres. Post treatment, it’s uncertain whether their length has been affected by the cancer or the treatment. The team hypothesizes that this likely explains why the previous studies have been so inconsistent. The results saw the inflection point at which rapid telomere shortening stabilizes and showed that cancer had hijacked the telomere shortening in order to flourish in the body.
The team explain that telomeres shorten every time a cell divides. The older you a person is, the more times each cell in their body has divided and the shorter their telomeres. Because cancer cells divide and grow rapidly, scientists would expect the cell would get so short it would self-destruct. However, that’s not what happens, with data findings showing that somehow, cancer finds a way to halt that process.
If scientists can identify how cancer hijacks the cell, conclude the team, then perhaps treatments could be developed to cause cancer cells to self-destruct without harming healthy cells.