The largest genomic study of cancer has just been published: an ambitious meta-analysis that reveals how tumors arise

The mother of all the cancer studies we have to date. A meta-analysis in which the genomes of more than 2,600 cancer patients worldwide have been analyzed shows us the most complete picture we have of this disease (which is not actually a disease as such) so far. The researchers behind the project say this could pave the way for better detecting mutations early and before tumors are generated.

Pan-Cancer Analysis of Whole Genomes (PCAWG) is the name given to the project and which has already been published in a series of articles in Nature. More than 1,300 researchers from all over the world have been involved in it, a total of 2,658 whole genomes and up to 38 different types of cancer have been analyzed. From 37 different countries and with the help of 13 supercomputers that have analyzed millions and millions of data collected from the genome. It is the largest and most detailed analysis we have ever done of cancer, investigating at the molecular level why each type of tumor arises.

DNA flaws that lead to cancer

To understand the relevance of the project you have to understand (in a very general way) how cancer appears in a person. Something that is actually a natural process and is part of evolution. In the same way that DNA mutations allow us to develop over different generations, these "failures" in copying DNA from one cell to another also give rise to tumors. Every time a cell divides to generate another copy, its DNA and among the billions of letters in the DNA, some other error is generated. These mistakes are harmless in most cases, but in certain cases they can lead to cancer.

What the PCAWG study has done, in essence, is analyze where, when and why these mutations that lead to cancer occur. In each cancer patient studied for the project, a genome of a tumor cell and a healthy cell has been analyzed. Comparing both genomes and after reading it letter by letter 30 times, it was possible to identify the mutations that differentiate both cells.

In 95% of the cases, at least one casual mutation has been identified and it has been concluded that an average of about five random mutations is required for the tumor to appear. However, it is something that can vary with each type of tumor.

Why are these mutations occurring? There are many factors and thousands of different combinations to get the tumor to occur. Mutations can appear due to sunlight, eating habits, smoking or simply by chance, for example, as we have already seen, there are many possibilities. Despite the complexity, the fact that so much data is available makes it possible to find common patterns to more easily identify cancer in its early stages.

Early detection and specific treatments

This meta-analysis, as large as it is, is not a cure for cancer. Yes, it is a very important step to help you better understand it at its origin. By analyzing the different mutations that occur in the genome, researchers can more easily develop specific treatments for each case, a kind of 'cancer vaccine'.

On the other hand, identifying the casual mutations that cause cancer years before the end of the process is reached may open the possibility of preventing the development of those cells that have mutated and thus slow the process. There is still much to do, what is clear is that this type of progress is of great help.

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