Large study sheds light on the genetic causes of thyroid cancer
An in-depth US study into thyroid cancer has identified new genes responsible for the disease and could help doctors tailor treatment in the future.
"The researchers have taken their analysis one step further, using the genetic data to make predictions about how severe the cancer may be" - Professor Rebecca Fitzgerald, Cancer Research UK
Researchers from The Cancer Genome Atlas Research Network looked at nearly 500 tumour samples to find genes that actively cause thyroid cancer when faulty – so-called ‘driver’ genes.
They identified a number of genes that had not previously been linked to the disease. The discovery reduces the proportion of cases with an unknown genetic cause from 25 per cent to just under four per cent.
And the researchers, writing in the journal Cell, have now proposed a way to predict how serious each case is, which may one day help doctors make decisions around treatment.
Project co-leader Professor Thomas J Giordano, of University of Michigan Medical School, said the understanding would “help separate those patients who need aggressive treatment from those whose tumour is never likely to grow or spread”.
Cases of thyroid cancer have doubled since the 1990s. Over 2,700 people are diagnosed with the disease each year in the UK.
The condition is more common in women than men, with around two-and-a-half times as many women diagnosed.
While the newly discovered genes help build a clearer picture of thyroid cancer’s genetic landscape, the team also found genetic faults that have already been linked to the disease.
The study revealed that the majority of thyroid cancers tested were caused by changes in one of two key genes: BRAF and RAS. But within these two groups the researchers observed further genetic diversity, suggesting that the disease may in fact be multiple different subtypes.
Until now, all thyroid cancers associated with BRAF have been regarded as essentially the same – an assumption questioned by the new research.
The other co-lead on the project, Dr Gad Getz, said: "Interestingly, we found that subsets of BRAF-mutated thyroid cancers are driving cancer through distinct mechanisms, and that some of these subsets are associated with higher risk and less differentiated cancers."
The research could lead to the reclassification of thyroid cancer based on the varying subtypes in order to allow doctors to distinguish between the slow-growing tumours from the aggressive tumours.
Professor Rebecca Fitzgerald, a Cancer Research UK expert in cancer genetics, said: "This study marks another important example of how in-depth analysis of the genetic faults present in tumour samples can split a particular type of cancer into distinct groups.
"In this study the researchers have taken their analysis one step further, using the genetic data to make predictions about how severe the cancer may be. Further research will be needed before these results can be used to make decisions about how patients with thyroid cancer should be treated."