Based on the largest study of cancer patients of its kind, scientists at the Centre Nacional d’Anàlisi Genòmica (CNAG-CRG), located in the Barcelona Science Park, have created a new way of classifying tumours. Clinicians can use genome sequencing to assign their patients’ tumours to one of sixteen groups in the new classification system, ten of which provide important information for the diagnosis and treatment of the disease, like whether an individual will respond to immunotherapy. The work is published in PLOS Computational Biology.

Researchers at the Centre Nacional d’Anàlisi Genòmica, part of the Centre for Genomic Regulation in Barcelona, analysed the mutations found in 2,583 patients with 37 different types of cancer. They detected a total of 45 million mutations across all tumours, of which at least 1.2 million were non-unique mutations, meaning they were found in the same location for two or more cancer patients.

Based on the number and type of non-unique mutations, researchers were able to classify the 2,583 primary tumours into one of sixteen groups, each of which have independent characteristics. Ten of these groups are clinically relevant, with the potential to help doctors make a more accurate diagnosis and select a more effective treatment course.

“Cancer is a complex disease that requires a bespoke course of action to diagnose, manage and treat effectively,” says Ivo Gut, director of the CNAG-CRG and senior author of the study. “Currently doctors look for individual mutations at specific locations in DNA, which has a limited view. Using whole genome sequencing provides a complete overview of the number of mutations in a tumour, allowing doctors to classify the cancer type and gain deeper understanding of disease, which can have important implications for the way they treat their patients.”

The findings also highlight other benefits for whole genome sequencing. “In a small percentage of patients, the origin of the cancer is unknown and the biopsy taken turns out to be from a metastasis instead of the primary tumour,” says Miranda Stobbe, lead author of the study. “If conventional analyses conclude that it is a metastatic tumour, but they cannot determine its origin, doctors will have to start scanning the rest of the patient to try to find the primary source. In some cases, the primary may already be gone, because of the response of the immune system, or the primary is too small to be detected. Our classification would get around that by assigning the tumour to one of 16 groups, providing important information on where the tumour originates from.”

►Reference article:

Stobbe MD, Thun GA, Diéguez-Docampo A, Oliva M, Whalley JP, Raineri E, et al. (2019) “Recurrent somatic mutations reveal new insights into consequences of mutagenic processes in cancer“. PLoS Comput Biol 15(11): e1007496. https://doi.org/10.1371/journal.pcbi.1007496

► More information: CNAG-CRG  website [+]