Pancreatic cancer risk has been linked to differences in the length of telomeres, which are the end caps on chromosomes in blood cells.
Telomeres maintain the stability of genes and shorten with age as cells divide. People of the same chronological age can have vastly different telomere lengths, meaning some people''s cells can be viewed as biologically older than cells from other people the same age.
Scientists at the University of Wisconsin Carbone Cancer Center (Madison, WI, USA) took blood samples from more than 1,500 people, 499 of them with a diagnosis of pancreatic cancer and 963 of them cancer-free control subject at the Mayo Clinic (Rochester, MN, USA).
The scientists were interested in the length of the telomeres found in white blood cells and they found a direct relationship with the risk of pancreatic cancer. Telomere length was measured in peripheral blood leukocytes (PBLs) using quantitative real-time polymerase chain reaction (PCR) in the cases with pancreatic cancer and the cancer-free controls. The results were computed using logistic generalized additive models (GAM) adjusting for multiple variables.
The investigators observed a significant nonlinear association between telomere length in peripheral blood samples and the risk for pancreatic cancer. Risk was lower among those with longer telomeres compared with shorter telomeres across a range from the 1st percentile to 90th percentile of telomere length. There was also some evidence for higher risk among those with telomeres in the longest extreme. Shortened telomeres in the blood cells are known to be associated with other types of cancer, including colon cancer.
The authors concluded that short telomeres in peripheral blood are associated with an increased risk for pancreatic cancer across most of the distribution of length, but extremely long telomeres may also be associated with higher risk. Halcyon G. Skinner, PhD, MPH, the lead author, said, “We know that people with many factors that are classically unhealthy also tend to have shorter telomeres. Those who have had stressful lives, exposed to chronic inflammation, have poor glucose control or smoked cigarettes tend to have shorter telomeres, and that can set the stage for genetic damage.” The study was published on October 23, 2012, in the journal Cancer Epidemiology Biomarkers and Prevention.