New genes for bowel cancer
Hot off the press, scientists funded by Cancer Research UK have found a common gene variation that can increase the risk of bowel cancer. This is the first time such a common gene version has been found. Several gene faults are known to increase the risk of bowel cancer, such as the genes APC and HNPCC, but these are very rare - they're carried by around one in 2,500 people, and thought to cause fewer than five in a hundred cases. But given that around a third of bowel cancers are thought to have an inherited component, there's more genes out there that we haven't found yet.
In total, the researchers studied the genetic makeup of more than 30,000 people, around half of whom had bowel cancer while the rest were unaffected. They pinned down a faulty region of DNA on chromosome 8, called 8q24. At the moment, we just know that this region is faulty - the actual gene responsible still needs to be identified.
The team found that around half the population carry the genetic fault, which increases the risk of bowel cancer by about 20%. So this increases the lifetime risk of the disease from about 1 in 20 to around 1 in 16 for people who carry the gene fault. And the scientists think that the fault may be linked to around 3,500 cases of bowel cancer every year. Intriguingly, other researchers recently found that the same gene fault is linked to prostate cancer.
Because the increase in bowel cancer risk from this gene fault is relatively small, it's not suitable for genetic testing at the moment. But if more low-risk genes are found in the future, then it might be possible to design a genetic test for a combination of such genes.