The next-generation DNA sequencing method detected all the mutations the conventional method did; it detected new mutations the conventional method didn't; and detected mutations present at much lower levels in the samples. The time taken for the 46 gene test also fitted into the standard turnaround time for samples at the lab.
There is definite benefit in screening some of the 46 genes included in the test; there is probable or likely clinical benefit in screening some of the others; mutations in further genes might be important in some cancers but not others; and the other genes, we don't know as yet. But having this information means researchers can investigate whether a mutation has biological significance.
'We can keep data, bank it and link it with anonymised clinical data on patients' cancers for future research,' explains Dr Schuh.
The test looks for mutations in 'hotspot' regions of each gene areas where mutations are more likely to occur. This does mean the test may miss up to 5% of mutations, as they can occur elsewhere, but this is still significantly better than the 'false negative' rate using current methods.
It can also detect mutations present in only 5% of the tumour cells present in a sample. This is much lower than is possible currently, and is important in being able to capture information from cells present in only small numbers in a tumour, but which are still important in driving cancer growth.
Having shown that it is possible to introduce the 46 gene test as an NHS service, the researchers are now moving on to investigate the potential of a test that will sequence 150 genes. The team will use the test first of all with 500 existing samples from patients taking part in cancer clinical trials to be able to compare the results retrospectively with information from the trials. They will then use the test with 1000 new cancer biopsies to better underst
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