Posted: February 2, 2017

Colon cancer is typically a disease of again.  It does occur, however, in people as young as thirty or even younger.  Increasingly important questions include: who should get screened before age 50 and is there a systematic way to identify such people.  Because of the easy access to gene sequencing, a growing number of genetic mutations has been identified in tumors of people with colon cancer.  Most well known is the mutation for microsatellite instability, which if present conveys a slightly better prognosis.   In people whose colon tumor is microsatellite unstable, the next step is to do a blood test to see whether they possess the germ-line mutation for one of a number of mismatch repair genes.  If present that person is deemed to have Lynch syndrome, and his or her entire family needs to be screened for that mutation, which, if present, predisposes to colon cancer at an early age.

Starting in 2004 the Cleveland Clinic began pioneering work in mass screening their patients for the presence of these mutations.  Their work has led to a recommendation  The US Government sponsored Health People 2020 has made universal testing for mutations a goal as well.   In a recent paper in JAMA Oncology, the people at Cleveland Clinic, together with a large group from Ohio State, have updated their work.  See this link for the abstract; Dr. Stark can provide the entire paper if you wish it, but can’t post it because of copyright issues.   The authors looked at all the patients in their colon cancer databases and selected all people under age 50 for further analysis.   Based on the work cited above, starting in 2004 they did comprehensive mutation analysis on all their colorectal cancer patients.  As new mutations were identified they were also screening for.  The big news in this paper is the presence of a mutation in 16% of their patients.  Most of these people had the mismatch repair gene cited above, but a smattering of other mutations was found as well.

What is the importance of this finding?  It underscores the importance of screening all people under age 50 for such mutations, because if found all their relatives need to be screening and they need to be followed more closely for the development of additional cancers, and not just colorectal cancer.   There is an increasing awareness that pro-active searching for people at increased risk of cancer is an important and fruitful endeavor.