Prostate Cancer Gene Also Raises Colon Cancer Risk

It's the first example of DNA spurring more than one cancer type, scientists say.

By E.J. Mundell
HealthDay Reporter
Monday, July 9, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

SUNDAY, July 8 (HealthDay News) -- Compelling evidence from four studies confirms that a key change in DNA previously linked to prostate cancer also raises colon cancer risk, scientists report.

They stress that the risk to any individual carrier of the rs6983267 variant gene -- which is located on a region of chromosome 8 called 8q24 -- are relatively slight. Overall, carriers of this variant have about a 20 percent higher risk of developing a colorectal malignancy compared to non-carriers, the researchers said.

The gene's real power comes in its prevalence.

According to scientists, the number of people who carry the variant on region 8q24 includes about half of the populations studied, researchers say.

"In other words, it is very common in the general population," said Dr. Malcolm Dunlop, of Cancer Research UK and the University of Edinburgh, Scotland.

Dunlop, the lead investigator on one of three studies published in the July 8 online edition of Nature Genetics, told reporters at a Friday news conference that "between 4 to 9 percent of all bowel cancers" may be traced to this particular chromosomal locus.

His team honed in on the 8q24 region after comparing the genomes of almost 7,500 colon cancer patients against those of almost 7,800 unaffected controls.

Similar results were found in a U.S. study that was led by Christopher Haiman of the University of Southern California, Los Angeles. His team combed through the DNA of more than 1,800 people from a variety of racial and ethnic backgrounds; comparing key differences in DNA against genes from more than 5,500 healthy controls.

Again, the rs6983267 variant conferred about a 22 percent increase in colorectal cancer risk, Haiman's team reported. Prior studies had already tied this variant to an increased risk for prostate cancer.

"This is the first common genetic risk factor that has been reproducibly associated with risks in multiple cancers," Haiman told reporters. "The association observed with this variant in both prostate and colorectal cancer provides very strong support for the hypothesis that there may be a common biological mechanism underlying cancer risk in this region of the genome."