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Gene mutation found to cause colon cancer
August 25, 1997
Web posted at: 11:44 p.m. EDT (0344 GMT)WASHINGTON (CNN) -- A seemingly harmless genetic mutation can cause one kind of inherited colorectal cancer, researchers reported Monday. The discovery has made possible a blood test for the defect which will be available soon, they said.
Researchers at Johns Hopkins University in Baltimore, who discovered the mutation, said it causes familial colorectal cancer (FCC), which accounts for between 15 percent and 50 percent of all cases of colon cancer.
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They said as far as they knew the mutation was present only in Ashkenazi Jews, or Jews of European descent. The cases are usually diagnosed when patients are in their 50s and 60s. More than 95 percent of the estimated 6 million Jews in the U.S. are Ashkenazi.
"There are approximately 11 million Askenazis in the world and we estimate 700,000 of them have this permutation, and are at risk," said Dr. Bert Vogelstein of Johns Hopkins Oncology Center.
"It creates an Achilles heel in the gene."
— Kenneth Kinzler, Johns Hopkins University
Vogelstein and his colleagues said they've developed a simple blood test for the defect. It is currently available only at Johns Hopkins and costs $200. Colon cancers are usually curable if caught early.
The mutation, described in the journal Nature Genetics, involves the APC gene, long known to be involved in colon cancer. The mutation "creates an Achilles heel in the gene," said Kenneth Kinzler, an assistant of oncology at Johns Hopkins.
"There are some people who inherit a completely defective, broken APC gene, and these patients develop hundreds of colon tumors," Kinsler said.
Researchers figure more than 680,000 people around the world carry the mutation, and have a 20 percent to 30 percent chance of getting colorectal cancer.
Find may aid other research
The research has implications for the rest of the population as well. The gene contains a common type of mutation, once thought harmless, and researchers say they will now search other genes for the same mutation to see if it might be responsible for other hereditary cancers.
Most of those diagnosed with colon cancer, like Baltimore Orioles outfielder Eric Davis, aren't Ashkenazi Jews, and have no family history of it. Doctors say everyone, especially those over 50, should be aware of warning signs.
"If you see blood, that's the No. 1 sign," said Dr. Lee Smith of Washington Hospital Center. "If you have a physical examination make sure screening of the rectum and colon are part of it."
Reporter Aileen Pincus and Reuters contributed to this report.
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- Cancer researchers find there are no easy answers - May 14, 1997
- Researchers identify gene linked to deadly cancers - March 28, 1997
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