The genetic evolution of a breast tumour is reported in Nature. The findings will help researchers to understand the changes that occur in tumours as disease progresses.
As tumours progress, they acquire new genetic mutations that can enable them to continue to grow and spread. Samuel Aparicio and colleagues used next generation sequencing techniques to chart the genetic mutations that occur in an oestrogen-receptor-alpha-positive breast tumour. This tumour type accounts for 15% of all breast cancers. The sample came from the original patient biopsy at diagnosis and from a secondary tumour from the same patient removed 9 years later, after the tumour had spread.
The team find 32 mutations present in the DNA of the secondary tumour, 19 of which were not present at all in the original tumour sample. Combined analysis of genome and transcriptome data revealed RNA-editing events that occur in the tumour, two of which had not been reported before.
Based on their findings, the authors propose that sequencing primary tumours, before therapy and before they become invasive, should make it easier to find gene candidates for understanding the events that trigger the initial cancer. Looking only at more aggressive tumour samples, where mutations are more numerous, will require many more specimens to make sense of the information.
Samuel Aparicio (BC Cancer Research Centre, Vancouver, Canada)
(C) Nature press release.
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