Screening every new colon cancer patient for a familial disorder called Lynch syndrome extends lives at a reasonable cost.

Lynch syndrome is caused by mutations in a set of genes that normally run quality control on the DNA of cells. The loss of such a molecular DNA inspector predisposes Lynch syndrome patients to tumor growth. Unusual patterns in the DNA of tumor cells or a missing inspector indicate that there is diminished quality control. As soon as a pathologist identifies a tumor that might be caused by the disorder, more tests are needed to determine if the patient carries a particular mutation.

The most cost-effective method involved checking whether tumors were missing any molecular quality inspectors, followed by DNA sequencing of the suspected gene.

Approximately 3% to 5% of colorectal tumors are caused by Lynch syndrome, which greatly increases the odds of colon and other cancers in a person's lifetime. Siblings and children of someone with Lynch syndrome each have a 50% chance of carrying the mutation, so the first diagnosis in a family reveals the risk for many relatives.

"This is a situation where, if you find out genetic information, you can improve your outcome," said Uri Ladabaum, MD, associate professor of gastroenterology and hepatology at the Stanford University School of Medicine (Stanford, CA, USA) and lead author of the study. Lynch syndrome patients can take defensive steps (such as yearly colonoscopies) that can either prevent cancer or alert them to get cancer treatment early, when it has the best chance of working.

Prof. Ladabaum and colleagues used computer simulations to compare the years of lives gained and the money spent if all new cases of colorectal cancer were tested for Lynch syndrome. They found that such screening programs could reduce cancer deaths at a price within the typical range of US healthcare costs. The study was published in the July 19, 2011, issue of Annals of Internal Medicine.

Prior to the availability of genetic testing, Lynch syndrome was identified by observant genetic counselors and physicians who noticed the high frequency of cancers in certain families. However, this method is not foolproof, especially if a patient does not know his or her family history. If Lynch syndrome is present a person's lifetime risk of developing colon cancer increases from 5% to 70%.

The study suggests that more medical centers could adopt tumor-screening policies like Stanford's. "A systematic approach to identify families with Lynch syndrome makes sense clinically, because it can save lives, and economically, because its costs are comparable to other things we choose to spend our healthcare dollars on," said Prof. Ladabaum. "We advocate establishing similar tumor-screening systems on a national level."

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