Cancer genes studies misleading, research shows

Common gene changes which have previously been linked to increased cancer risk may not be as significant as previously thought, a study published in the Journal of the National Cancer Institute last week suggests. The researchers, based at the University of Ioannina School of Medicine in Greece, found that, in the majority of cases, the data from such studies failed to stand up when pooled together.

The study highlights the need for caution over the growing number of common genetic variants reportedly associated with a wide range of chronic diseases, says Ioannidis of the University of Ioannina School of Medicine in Greece.

'The whole thing about genetic variations and links to diseases like cancer are very exciting, but the general public should be quite cautious about jumping to the conclusion that if they have a change in one gene or another they are doomed,' Ioannidis, the study's leader, told Reuters. 'Genetic effects are very complex and very subtle and we need to know a lot more before we can make strong recommendations based on genetic profiles.'

Ioannidis and his colleague Paolo Vineis of Imperial College London pooled the data from 241 published studies linking various cancers to genetic changes involved in DNA repair, thought to be instrumental in carcinogenesis. They found only two genes that appeared to demonstrate a credible link - XRCC1 and ERCC2 - both associated with and increased risk of lung cancer.

Ioannidis and Paolo believe that there are two possible explanations for these results: Either the method of identifying disease risk genes by comparing the genomes of diseased or healthy individuals, or the importance of DNA repair genes in the development of cancer, are overrated.

Scientists have long understood that many common diseases, including cancer, result from complex interactions between both genetic and environmental factors. Ioannidis and Paolo believe that many more studies would be needed to fully understand these interactions before the knowledge gained from such studies can be of benefit to humankind.