April 21, 2010
Statin Cancer Risk Reduction Depends On Gene Variants

While one study casts doubt on use of cholesterol-lowering statins to lower colorectal cancer risk another study finds that genetic variants are key to whether statins will cut cancer risk.

In this study, the research team genotyped 40 candidate genes known to be important for synthesis and metabolism of cholesterol in people who participated in a population case-control study of colorectal cancer in northern Israel. Included were 1,780 colon cancer patients and 1,863 people who did not have colorectal cancer, and many of the participants, who were predominantly Caucasian, had used statins for a long time. In the initial study, statin use was associated with a 50 percent relative risk of developing colorectal cancer in this population.

Included in the 40 genes were six SNPs, or DNA sequences, within the HMGCR gene, which produces a critical enzyme involved in formation of cholesterol.

They found one SNP within HMGCR that was associated with statin protection against colorectal cancer. A follow-up pharmacogenetic analysis showed that the protective association was significantly stronger among individuals with what they dubbed the "A" SNP allele, or variant, compared with people who had a "T" variant. Because a person inherits two variants, one from each parent, the stronger colorectal cancer protection came from individuals with the A/A HMGCR genotype, compared with those with the T/T genotype. Individuals with an A/T genotype had intermediate protection against colorectal cancer -- levels that varied between that seen for A/A and T/T genotypes.

Since genetic variants occur in different frequencies in different populations a lot of medical research that does not control for genetic variants ends up producing conflicting results depending on the genetic endowment of experimental subjects.

A gene test might eventually make the taking of statins more compelling for those with the right genetic variants.

ďItís the exact same mechanism for lowering cholesterol as it is for lowering colon cancer risk. This is true only for those people who are actually taking statins. The gene test by itself doesnít predict whether youíre at an increased risk of colon cancer; it predicts only how well statins lower the risk,Ē Gruber says.

The researchers point out that itís easy to know if statins are successfully lowering cholesterol, but their effect on colorectal cancer prevention is not as apparent. Thatís where a gene test would come in.

Statins also cause harmful side effects in some users. If genetic testing can flag who will have bad reactions to statins and also who will have the most cancer reduction benefits then the argument for taking statins will become stronger for some while at the same time becoming much weaker for others.

This is part of a larger pattern in increased value from genetic testing. In just 5 years I expect the number of potential benefits from genetic testing to become very compelling.

Share |      Randall Parker, 2010 April 21 11:38 PM  Aging Genetics


Comments
David Becker, Ph.D. said at April 22, 2010 11:55 AM:

The problem is that, with the coming of Obamacare, none of this information will have clinical relevance. Nationalized health care systems do not take care of the elderly and potentially sick and will find it too expensive to do genetic screening to see who might benefit from statins in this regard. If a few old people die from colorectal cancer who might otherwise have been saved, well, that's too bad. The system will appreciate the fact that there will be fewer seniors sucking up medical benefits.

Denver said at April 22, 2010 2:00 PM:

Not only do the recent Congressional excesses need to be overturned; protections within Federal Law and the US Constitution need to be implemented to stop other Marxists certain to be elected in the future. Constitutionally forbidding income redistribution and taxation at the federal level would be a good place to start.

Good day.

AB said at April 22, 2010 6:01 PM:

Doctors use check lists to practice medicine today. Consumers think this is science. They actually believe studies from drug companies are the height of knowledge. When I was in graduate school we had to deconstruct journal articles for poor methodology. Even if it was good, the problems of a double blind with drugs and people are huge. These topics are discussed behind the scenes by those interested in methodology. But doctors never learn this so they get their drug company sponsored and designed education and come out ready to be a good automaton for Obamacare.

They can jail me, fine me, do what they want. I will not participate. (as my IP address has just been logged...)

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