Instead of being one disease, a certain aggressive form of blood cancer actually has 11 distinct subtypes with different clinical features and genetic profiles, new research in the United Kingdom has revealed.
This groundbreaking research may explain why some people with the major blood cancer known as acute myeloid leukemia (AML) show significant differences in survival. The discovery could also aid improvements in patient diagnosis and treatment.
AML often begins in the bone marrow, and in some cases, it rapidly spreads to the bloodstream. The illness can also spread to the spleen, lymph nodes, liver, central nervous system and other organs.
Previous studies have found eight different subtypes of AML. However, when researchers from Wellcome Trust Sanger Institute examined AML patients involved in several studies, they found that no one had matched any of the eight subgroups.
Co-led by Peter Campbell, scientists analyzed cancer DNA from bone marrow and blood samples of 1,540 AML patients who participated in three international clinical trials. They then unpicked patterns between gene mutations, as well as the way leukemia progressed.
Although many of the patients possessed unique collections of gene mutations, in the end, Campbell and his team discovered that AML is an umbrella term for at least 11 different classes of leukemia.
Eight of the 11 subtypes have been, indeed, previously proposed. Campbell says within each of these 11 classes, there were some key genetic events that could only be seen as a certain subtype of leukemia.
Furthermore, with the new classification system, 84 percent of patients involved in the trials fell into one or more of the 11 subgroups.
Campbell and his team believe that the findings of the study help explain the large variations in survival, symptom and the age at which patients develop AML.
Some of the AML subtypes actually have cure rates of about 80 to 90 percent, while others only have cure rates of 5 to 10 percent, he says.
With the research, doctors could have a much more informed discussion with patients about the realistic chances of failure or success with a certain treatment. It could also pave the way for more personalized and appropriate treatments for each AML patient.
Matt Kaiser of Bloodwise, a charity in the UK, believes the findings could lead to new clinical trials with best types of treatment for each AML subtype.
"There is a great urgency for new treatments and new treatment approaches in this disease," says Kaiser.
Still, the study has its limitations, including the fact that participants were aged up to 65 years old. Kaiser says extending the analysis to patients over 65 will be largely beneficial.
Details of the new study are published in the New England Journal of Medicine.