Telomeres, repeated sequences of DNA that shorten every time a cell divides, have been linked to an increased cancer risk. The length of the telomere “caps” of DNA that protect the tips of chromosomes may provide an avenue for future therapy.
The researchers presenting at American Association for Cancer Research analyzed blood samples and health data on more than 28,000 Chinese people enrolled in the Singapore Chinese Health Study, which has followed the health outcomes of participants since 1993. As of the end of 2015, 4,060 participants had developed cancer.
Participants were divided into five groups, based on how much longer their telomeres were than expected. The group with the longest telomeres had 33 percent higher odds of developing any cancer than the group with the shortest telomeres, after taking into account the effect of age, sex, education and smoking habits. That group also had 66 percent higher odds of developing lung cancer, 39 percent higher odds of developing breast cancer, 55 percent higher odds of developing prostate cancer and 37 percent higher odds of developing colorectal cancer.
Of all the cancers, pancreatic had the largest increase in incidence related to longer telomeres, with participants in the highest one-fifth for telomere length at nearly 2.6 times the odds of developing pancreatic cancer, compared to those in the lowest one-fifth for telomere length. Only the risk of liver cancer went down with longer telomeres.
For three cancers, the risk was greatest for both the groups with extreme short and extreme long telomeres—creating a “U-shaped” risk curve. Participants in the group with the shortest telomere length had 63 percent higher odds of stomach cancer, 72 percent higher odds of bladder cancer and 115 percent higher odds of leukemia than the group in the middle of the curve.
The group with the longest telomeres had 55 percent higher odds of stomach cancer, 117 percent higher odds of bladder cancer and 68 percent higher odds of leukemia.
Long Telomeres Linked To Higher Cancer Risk