Scientists also discovered how to track the evolution of mutations with a single tumor biopsy. This group confirmed that the initial mutations generally appeared years or decades before the diagnosis of the cancers, suggesting that many could be detected and treated much earlier.
Another team found new patterns of mutations that result from environmental exposures, such as tobacco smoke. The articles explore topics such as the frequency with which tumor genomes contain DNA from viruses that may have triggered cancer, which happens in 13% of samples.
Marcin Cieslik and Arul Chinnaiyan, from the University of Michigan, who signed a commentary on the published studies, say that information can now be obtained with cheaper tests than complete genome sequencing. "It remains to be seen whether whole genome sequencing is the best method in the clinic," they say, but the wealth of data from the PCAWG study, which is available free of charge to researchers, will help biologists understand the mechanisms of cancer.
These scientists further explain that targeted drugs may be less toxic and more powerful than chemotherapy, but that the tumors of most patients start growing again when some cells that resist the drug start to expand. Therefore, the patient may need another medication to kill resistant cells.
"It is true that this type of sequencing does not mean that all cancers are cured  But it does indicate where we should think about developing drugs to prevent resistance or treat it when it arises," says Peter Campbell. "Ultimately, what we want make use of these technologies to identify personalized treatments for each patient ", he stated.
A new way of analyzing cancer data
For more than a decade, scientists have been working on cancer genome decoding, but most of the data had limited clinical data from the sample donors. The first samples collected for the Cancer Genome Atlas, the sequencing project carried out from 2006 to 2018 and co-financed by the US National Cancer Institute and the National Human Genome Research Institute, they had little more information than the donor's gender, diagnosis and age, but lacked family registry or medical history data. person, the type of treatment they received and how they responded, which is essential to understand how the genome can be put to work to help patients.
Scientists now say that the new generation of cancer genome sequencing projects is changing that, although collecting detailed clinical information is still difficult and expensive, and also means an increased risk of personal exposure and potential data protection breach.
Several organizations are working to transform health records into a format that can be accessed and studied more easily, but in safety. The American Cancer Research Association's GENIE project compiled 70,000 records of tumor DNA sequences and real-world clinical data, while the UK's 100,000 genome project also aims to combine DNA sequences with clinical information for a variety of conditions. The International Cancer Genome Consortium, which has coordinated much of the tumor sequencing work so far, has also launched a new phase, this time with a focus on clinical information.
Researchers recognize that gathering a large number of samples is a powerful way to find genetic changes that can lead to cancer and provides a starting point for learning how that happens, but the real return on investment will happen when that information can be used to adapt therapy to individual patients. And for this to be achieved, it is essential to obtain basic clinical information about the study participants.
Even so, a catalog of mutations is not the complete solution. When cancer genome sequencing projects were launched, they were expected to provide a catalog of mutations that give rise to cancer and reveal broad patterns on which researchers could base drug development. But many cancers have turned out to be more complex than expected and very different sets of mutations can give rise to the same cancer.
The data obtained in the PCAWG study can be freely accessed through the website and downloaded for analysis of the biologists and scientists involved in cancer research and the software developed for the consortium for alignment and quality control is also public and has been published under the license GNU General Public License v3.0. The analysis software is in a GitHub repository, where the study's analysis models were saved.
Editor's Note: Images and a video have been added