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Telomere length may affect colorectal cancer risk
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In younger patients with colorectal cancer, long telomeres were associated with a 31% increased risk of developing the disease, according to findings presented in a press conference.
Lisa A. Boardman, MD, associate professor of medicine, Mayo Clinic, Rochester, Minn., said the aim of the study was to determine whether associations between telomere length and colorectal cancer exist.
The researchers used quantitative polymerase chain reaction to measure peripheral blood leukocyte DNA telomere length in 772 patients diagnosed with microsatellite stable colorectal cancer. Eligible patients were younger than 60 years and had no history of chemoradiotherapy. Results from patients were compared with those from 1,660 age- and sex-matched controls.
Patients were more likely than controls to have diabetes mellitus (P=.005), to eat fewer fruits (P=.03) or vegetables (P=.01) and to eat more red meat (P=.01), according to Boardman. Additionally, she said patients regularly took less calcium (P=.002) and folic acid (P=.06) than controls.
Other data indicated that contraception (P=.02) or hormone therapy (P=.0003) were used less frequently by women with colorectal cancer than controls.
“The relationship between the natural log of telomere length and the outcome cancer was in a nonlinear U-shaped distribution,” Boardman said, noting that the OR for colorectal cancer in those with the shortest and longest telomere lengths was 1.14 (P=.01).
This OR remained increased after adjusting for the aforementioned variables. “Long constitutional telomere length is independently associated with an increased risk for colorectal cancer,” she said.
Boardman said the researchers anticipated that some patients with early-onset colon cancer would have shorter telomeres compared with others in the same age group who did not have cancer. However, they found that those in the patient group had telomeres that were longer than could be expected, even for those without colon cancer
“This suggests that there may be two different mechanisms that affect telomere length and that set up susceptibility to cancer,” Boardman said.
Part of the mechanism may be age-related, according to Boardman. She said among patients younger than 50 years, those with telomeres in the 95th percentile in length had a 31% higher risk for developing colorectal cancer than those with telomeres in the 50th percentile.
Boardman said shorter telomere length was associated with a 22% increase in risk for colon cancer in the older populations.
“In younger patients, longer telomere length was associated with increased risk,” she said. “However, people older than 60 with the longest telomere length had the lowest risk of developing colorectal cancer.”