Cancer is often said to be many diseases, rather than one disease, because of the vastly different way that different kinds of cancers are known to behave. But in a series of papers published in the journal ‘Nature’, scientists from several international consortium have mapped the handful of genes whose mutation causes several different kinds of cancer. This raises hopes of treatment tailored for specific cancers.
“On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete,” researchers wrote.
About half of these mutations occurred in the same set of nine genes. They analysed 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). Driver genes are genes whose mutations are linked to development of a disease, in this case cancer.
Dr Ashok Vaid, chairman, Medical and Haemato Oncology at Medanta, the Medicity, said: “It is an exciting development. Identifying the driver gene means a lot because that decides whether I can do targeted treatment or go with traditional options like chemotherapy. But the time taken for developing a drug from identifying a gene varies. In case of ALK-1, identified as the driver gene for 5-7 per cent lung cancers, the time from its identification in 2006-7 to a drug was just five years.”
However the path is not always as short. Currently, when a tumour is sent for genetic analysis, there is capacity to analyse about 1,000 genes in a standard laboratory. Of these, less than 200 are implicated in various cancers, of which there are medicines for less than 40, Dr Vaid said.
“For more than 30 cancers we now know what specific genetic changes are likely to happen and when these are likely to take place. Unlocking these patterns means it should now be possible to develop new diagnostic tests that pick up signs of cancer earlier, “ Peter Van Loo, of Francis Crick Institute in London, one of the project leaders of the ‘Nature’ papers, said in a media statement.
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