Testing colon tumors can lead to early cancer detection

According to the researchers, pre-screening will help determine the need for genetic counselling or testing for the syndrome.

Ohio State University researchers have suggested that after surgery, all colon tumors should be tested to prevent a patient from inheriting a syndrome that carries an extremely high risk of cancer.

According to the new study published in the New England Journal of Medicine, there are around two or three per cent of people with colon cancer that probably have mutations for the inherited syndrome known as the Lynch Syndrome.

According to the researchers, pre-screening will help determine the need for genetic counselling or testing for the syndrome. Pre-screening can be done using a relatively inexpensive microscopy test and it might help doctors estimate a patient's long-term prognosis better.

Lynch Syndrome is usually caused by a mutation in one of four genes. One out of two first-degree relatives of those with the syndrome are also likely to have the mutations.

"These are particularly bad mutations. A person who has one of these mutations has an almost 100 per cent lifetime risk of cancer," said lead researcher Albert de la Chapelle.

Chapelle said that the risk is highest for colon cancer, followed by a lower risk of uterine cancer and several other cancers.

Researchers involved 1,066 patients with newly diagnosed colorectal cancer in the study. Tumor cells from each patient were tested for microsatellite instability (MSI), a hallmark of Lynch syndrome. MSI occurs in more than 90 per cent of Lynch Syndrome tumors.

To learn the frequency of Lynch syndrome generally, the researchers tested all the tumors for the presence of MSI. They also used an alternative method to pre-screen for mutations known as immunohistochemistry. Of the 1,066 tumors tested, 208 showed MSI. Of these, 23 (2.2 per cent of the total) had Lynch syndrome mutations. Five of the tumors came from patients that did not meet the usual criteria for diagnosing Lynch Syndrome. That diagnosis is largely based on family history and age.

"There are now 52 people who know they have Lynch Syndrome because they had a relative in this study. It's important that people who have this syndrome know they have it because there is a good chance we can prevent cancer from developing or at least detect it early when it is more easily treated," said first author Heather Hampel.