Colon Cancer Risk Traced To Common Ancestor

Without proper clinical care, people with the AFAP mutation have a greater than two in three risk of colon cancer by age 80, compared to about one in 24 for the general population. The researchers discovered that the two families share common ancestors, a couple who came to America from England in the 1630s, about the time of the Pilgrims.

The Utah family in this study has more than 7,000 descendants spanning nine generations recorded in the Utah population database (UPDB). Members of this one family account for 0.15% of all colorectal cancers reported in Utah from 1966 to 1995. Based on that percentage, researchers expected to see eight cases of colon cancer from this one family among the over 5,000 reported between 1996 and 2003; but after previous research identified this family as affected by AFAP, aggressive education and clinical intervention resulted in only one mutation carrier in the family being diagnosed with colon cancer during those years. The study was published in the January 2008 issue of the journal Clinical Gastroenterology and Hepatology.

"The fact that this mutation can be traced so far back in time suggests that it could be carried by many more families in the United States than is currently known,” said lead author Deborah Neklason, Ph.D. "In fact, this founder mutation might be related to many colon cancer cases in the United States.”

Clinical recognition of AFAP can be difficult because AFAP-related colon cancer develops on average around 50 years of age, as do sporadic (non-hereditary) colon cancers. About one-third of people with AFAP also have only a few polyps, again similar to that for sporadic colon cancer, and they may also have a limited family history.


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