There may be racial diferences in susceptibility to bowel cancer
Three more genes that raise bowel cancer risk, including one affecting only some races, have been identified.
UK scientists found one of the genes increased risk in people of European descent, but not Japanese people, reports the journal Nature Genetics.
With four gene mutations already linked to the cancer, scientists hope to work on ways to predict people at high risk.
They hope eventually to diagnose the disease earlier, or prevent it completely in some people.
Bowel cancer is frequently not detected until the disease is well-established, sharply reducing the chances of successful treatment.
The NHS is currently rolling out a bowel cancer screening programme across England, which, it is hoped, will reduce the number of deaths by spotting cancer at an early stage.
However, knowing which genes increase the risk of cancer could allow doctors to find people who need to be followed more closely, or even receive preventive treatment before cancer has emerged.
The three latest gene mutations to be linked to bowel cancer are in addition to four others which point to increased risk, and scientists are now becoming more confident that, together, they could allow high-risk patients to be identified.
However, one of the genes has been found to increase risk in people of European descent, but not Japanese people - the first time this has been found for a bowel cancer gene.
This could provide clues as to whether Japanese people have a make-up which is generally more resistant to the disease.
Professor Malcolm Dunlop, at the Institute of Genetics and Molecular Medicine at the University of Edinburgh and who led the research, said: "This is the first time that a race-specific effect has been found for a genetic marker.
"It's an important step forward in our knowledge of the causes of bowel cancer, bringing us ever closer to a genetic test for those at high risk of the disease."
However, he warned that a genetic screening test for bowel cancer was still some way off.
The other two genes were found jointly by Edinburgh and London-based scientists at Cancer Research UK's London Research Unit, and the Institute of Cancer Research.
Dr Lesley Walker, from Cancer Research UK, said: "We can now begin to explain some of the difference in rates of the disease between populations through specific genes.
"This work will continue to bring knowledge that will eventually allow us to test people with a family history of the disease, catching cancer earlier in those who are at the highest risk or preventing it all together."
A spokesman for the charity Bowel Cancer UK also welcomed the findings.
"Research into the genetic links to bowel cancer is one of the most groundbreaking and potentially fruitful areas of identifying specific populations who might be at increased risk of the disease, including in Europe."