Britain’s third biggest cancer – New genetic link

April 26, 2009


Bowel cancer is the third most common cancer in the UK with 36,500 people being diagnosed each year. It is also the second greatest cause of cancer death, currently around 100 people each day.

Anything that can help identify and treat a disease which kills over 15,000 people a year is very welcome and now a joint study funded by Cancer Research UK has found a genetic variant which they believe can promote the development of bowel cancer.

The study involved scientists in the UK, Spain and The Netherlands and sheds new light on how this disease develops and could lead to new treatments being designed. Common genetic variants that give people a higher risk of bowel cancer have already been identified, but scientists didn’t know how they might be driving cancer development. This new study goes one step further by showing how a precise DNA sequence could cause the biological changes that ultimately lead to cancer.

They identified 10 different genetic variants that increasedbowel cancer risk, concluding that people who had all the variants were at six times higher risk of developing it. They honed in on the genetic variant that conferred the strongest risk of bowel cancer, hypothesising that it was therefore key to driving cancer development. Laboratory experiments supported the scientists’ theory, showing the key genetic variant stopped the nearby SMAD7 gene turning on properly, and that disrupting this gene promoted cancer development. The SMAD7 gene is normally involved in cell growth and death so, by reducing the gene’s effect, the variant allows cancerous cells to grow.

Although the extra risk from having this DNA is modest, it is still highly significant because a large proportion of the population have the variant as part of their genetic makeup. Understanding cancer development in such detail will help in the search for new drugs, as any steps identified in the cancer process are potential places to intervene with treatments and research is now reaching a point where cancer drugs will be able to be targeted at the individual’s own genes for maximum effectiveness.


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