Genetic diversity in cancerous tumours eludes scientists

Although one day scientists might be able to personalise cancer treatment by targeting the genetic profile of a tumour, this vision remains a challenge as researchers discover that there is a huge diversity in the genetics of a single tumour.

According to research undertaken by scientists from Cancer Research UK, taking a sample from one part of a tumour may not reveal its full genetic identity.

The scientists carried out the first genome-wide analysis of the genetic variations between different regions of the same tumour, using samples of advanced kidney cancer donated by patients being treated at London’s Royal Marsden Hospital.

Their results, published in the New England Journal of Medicine, show that two thirds of genetic faults were not repeated across the biopsies from the same tumour.

Even samples next to each other in the tumour were not identical.

One region of a tumour could display gene expression associated with a good prognosis, whilst signatures in another region of the same tumour could be associated with a poor prognosis.

The findings may explain why personalised cancer treatments based on biomarkers from tumour biopsies are not always successful, and also why cancers are so difficult to treat once they have spread.

Lead author Professor Charles Swanton explained that cancers adapt as they grow along ‘Darwinian principles’ of evolution. He said: "We need to think of tumours like trees, with common mutations in the trunk but the more they spread into the branches the greater the genetic diversity."

The findings underline the importance of early diagnosis of cancer before it spreads, as well as the need to target common mutations in the ‘trunk’ of the cancer.

This news comes after scientists in the US have found a way to screen cancer patients for a wide range of cancer-causing genetic mutations.

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