Scientists have discovered that a major type of blood cancer is at least 11 different diseases, which could pave the way for better, targeted treatments in the future.
Researchers said that acute myeloid leukaemia (AML) is not a single disorder, but at least 11 different diseases comprising different constellations of genetic changes.
They believe these genetic changes explain differences in survival among AML patients and said the findings could help doctors create tailor-made treatments for leukaemia patients, which could boost survival rates.
Acute myeloid leukaemia (AML) is an aggressive blood cancer that affects people of all ages. It develops in cells in the bone marrow and is often treated with chemotherapy.
Researchers from the Wellcome Trust Sanger Institute studied 1,540 patients with AML that were enrolled in clinical trials.
They analysed more than 100 genes known to cause leukaemia, to identify common genetic themes behind the development of the disease.
They found that the patients were divided into at least 11 major groups, each with different constellations of genetic changes and distinctive clinical features.
The study also showed that most patients had a unique combination of genetic changes driving their leukaemia. This helps explain why survival rates in AML patients varies so much.
Having full knowledge of the genetic make-up of a patient's leukaemia improves the ability to predict whether that patient would be cured with current treatments, scientists said.
They believe this information could be used to design new clinical trials to develop the best treatments for each AML subtype.
"Two people may have what looks like the same leukaemia down the microscope, but we find extensive differences between those leukaemias at the genetic level.
"These genetic differences can explain so much of why one of those patients will be cured, while the other will not, despite receiving the exact same treatment."
He continued: "We have shown that AML is an umbrella term for a group of at least 11 different types of leukaemia. We can now start to decode these genetics to shape clinical trials and develop diagnostics."
By using a comprehensive approach, scientists will be able to understand the complex interplay between the genetic changes seen in a cancer and the clinical outcomes of that cancer.
This requires full genetic analysis of samples from large numbers of patients matched with detailed information about the treatment and survival of those patients.
Further research into leukaemia, as well as other cancers, will allow researchers to understand the patterns of how the disease develops and how patients are going to respond to treatment.
Professor Hartmut Döhner, chair of the German-Austrian AML Study Group, said: "This landmark study has showcased the importance of international collaboration between academic institutions and clinical trials and the large scale of the study.
"These results represent a major step forward in translating the exciting findings from molecular genetics into better disease classification, diagnosis, and improved care of our patients with acute myeloid leukaemia."
Dr Elli Papaemmanuil, co-author from the Sanger Institute, said: "Leukaemia is a global problem with poor outcomes for most patients.
"For the first time we untangled the genetic complexity seen in most AML cancer genomes into distinct evolutionary paths that lead to AML.
"By understanding these paths we can help develop more appropriate treatments for individual patients with AML."
Dr Áine McCarthy, from Cancer Research UK, welcomed the findings.
"Science such as this continues to offer new insights into cancer which can help us achieve our goal of beating the disease," she said.
"We need to learn more from clinical trials to find out whether tailoring treatment based on these subgroups boosts the number of people surviving the disease."