High blood sugar levels in older women linked to colorectal cancer
High Blood Sugar Levels in Older Women Linked to Colorectal Cancer
ScienceDaily (Nov. 29, 2011) — Elevated blood sugar levels are associated with an increased risk of colorectal cancer, according to a study led by researchers at Albert Einstein College of Medicine of Yeshiva University. The findings, observed in nearly 5,000 postmenopausal women, appear in the Nov. 29 online edition of the British Journal of Cancer.
According to the American Cancer Society, colorectal cancer is the third
most commonly diagnosed cancer and the third leading cause of cancer death
in both men and women in the U.S. Statistics compiled by the U.S. Centers
for Disease Control and Prevention for 2007 (the most recent year for which
figures are available) show that 142,672 Americans were diagnosed with colorectal
cancer, including 69,917 women; the 53,219 deaths from colorectal cancer that year
were divided almost equally between men and women.
The Einstein study involved women who were enrolled in the National Institutes of Health””s
landmark Women””s Health Initiative study. For these women, fasting blood sugar and
insulin levels had been measured at baseline (i.e., the start of the study) and then
several more times over the next 12 years.
By the end of the 12-year period, 81 of the women had developed colorectal cancer.
The researchers found that elevated baseline glucose levels were associated with increased
colorectal cancer risk — and that women in the highest third of baseline glucose levels
were nearly twice as likely to have developed colorectal cancer as women in the
lowest third of blood glucose levels. Results were similar when the scientists looked at
repeated glucose measurements over time.
No association was found between insulin levels and risk for colorectal cancer.
Obesity — usually accompanied by elevated blood levels of insulin and glucose — is a known
risk factor for colorectal cancer. Researchers have long suspected that obesity’s influence
on colorectal cancer risk stems from the elevated insulin levels it causes.
But the Einstein study suggests that obesity’s impact on this cancer may be due
to elevated glucose levels, or to some factor associated with elevated glucose levels.
“The next challenge is to find the mechanism by which chronically elevated blood glucose
levels may lead to colorectal cancer,” said Geoffrey Kabat, Ph.D., a senior epidemiologist at
Einstein and lead author of the paper. “It’s possible that elevated glucose levels are linked
to increased blood levels of growth factors and inflammatory factors that spur the growth of
intestinal polyps, some of which later develop into cancer.”
The paper is titled “A Longitudinal Study of Serum Insulin and Glucose Levels in Relation to
Colorectal Cancer Risk among Postmenopausal Women.”
Other Einstein authors are Mimi Kim, Sc.D., and Howard Strickler M.D.,
both professors in the department of epidemiology and population health,
and senior author Thomas E. Rohan, M.D., Ph.D., professor and chair of epidemiology and population health.
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