High levels of "good" cholesterol may reduce the risk of colon cancer, a new study suggests.
If other studies confirm this finding, people with low levels of high-density lipoprotein (HDL) cholesterol should "be advised to change their lifestyle to reduce their risk of colon cancer," said lead researcher Dr Bas Bueno-de-Mesquita, from the department of gastroenterology and hepatology at the National Institute for Public Health and the Environment in Bilthoven, the Netherlands.
Cutting "bad" (LDL) cholesterol and increasing "good" (HDL) cholesterol already are known to reduce the risk for heart disease, and this new study provides another reason to pay attention to your blood cholesterol numbers.
For the study, published online in Gut, the researchers compared 1,238 people with colorectal cancer to 1,238 healthy people. Of those with cancer, 779 had colon cancer and 459 had rectal cancer.
Blood and diet tested
The researchers reviewed the results of blood samples and dietary-lifestyle questionnaires provided by participants enrolled in the European Prospective Investigation into Cancer and Nutrition study, a long-term look at the effect of diet on cancer in 10 countries.
The investigators found that those with the highest levels of HDL cholesterol and another blood fat called apolipoprotein A (apoA) had the least chance of developing colon cancer, but no impact was seen on rectal cancer.
"This association is independent of some other markers in the blood that are related to the development of cancer," Bueno-de-Mesquita said. Those markers include inflammation, insulin resistance and oxygen free radicals.
For each 16.6 milligrams per deciliter (mg/dL) increase in HDL and 32 mg/dL increase in apoA, the risk of colon cancer was cut by 22 % and 18%, respectively, Bueno-de-Mesquita's team found.
But for a subset of patients followed for more than two years, only high HDL levels were linked with a lower risk of colon cancer.
The researchers speculate that HDL's anti-inflammatory properties may explain the finding, but say further research is needed to tease out the specific cause. They also acknowledged that the short follow-up period - just 3.8 years - is a limitation to their study.
HDL and colon cancer
Depending on the results of such investigations, HDL levels may someday be a useful tool in moderating a patient's colon cancer risk, the authors stated.
"Currently, the best recommendation to reduce one's risk [of colon cancer] is to stop smoking, increase physical activity, reduce obesity and abdominal fatness and limit intakes of alcohol and red and processed meats," Bueno-de-Mesquita said.
Commenting on the study, Eric Jacobs, strategic director of pharmacoepidemiology at the American Cancer Society, said that "this important study is well designed and the largest ever study of HDL cholesterol and colon cancer risk."
But, he noted, "the link between HDL and colon cancer needs to be confirmed in other studies and could reflect the effect of biological factors correlated with HDL, rather than an effect of HDL itself."
In addition, Jacobs stated, "No matter what the exact biology, we do know that getting more exercise is a good way to both improve HDL levels and lower risk of several cancers, including colon cancer."
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