'Landmark' study splits breast cancer into 10 types

The hunt for breast cancer biomarkers has been going on for many years, from the discovery of HER2 and BRCA1 in the 1980s and 1990s to more recent discoveries, including chemoresistance proteins. For treatment, breast cancers are often divided into groups according to the presence or absence of receptors for estrogen (ER), progesterone (PR) or human epidermal growth factor (HER2) (or even the absence of all three), or simply from how they look under the microscope.

A recent study, described as "landmark" by sponsor Cancer Research UK, has used genetic biomarkers to split cancer up into 10 types, based on clusters of genetic markers, and these could help predict which treatments would be more effective, and what the outcomes for patients are likely to be.

Researchers from the Canadian-UK consortium METABRIC (Molecular Taxonomy of Breast Cancer International Consortium) screened around 2,000 samples of breast cancer tissue to find genetic variants, including inherited changes (known as copy number aberrations or CNAs and single nucleotide polymorphisms or SNPs) and changes that develop in the tumor (acquired somatic CNAs). This is the largest genetic study of breast cancer tissue carried out to date, according to the charity.

The researchers found a number of known and potential cancer genes, including some completely new genes, and used clusters of these to create 10 subgroups, known as IntClust one to 10, according to survival.

Study co-lead author, Professor Carlos Caldas, senior group leader at Cancer Research UK's Cambridge Research Institute and the Department of Oncology, University of Cambridge, said: "Our results will pave the way for doctors in the future to diagnose the type of breast cancer a woman has, the types of drugs that will work, and those that won't, in a much more precise way than is currently possible."

"This landmark study will completely change the way we look at breast cancer. It's the result of decades of research by our scientists to identify the causes and drivers of the disease, which included a pivotal role in decoding the well-known BRCA genes," said Dr. Harpal Kumar, chief executive of Cancer Research UK.

The next step will be to look at the behavior of the tumors in each subgroup, for example how they grow or how much they spread, and to work out treatment plans for each--according to the BBC, only one type has a personalized treatment so far. Though these results are at least three years away from the clinic, they could make a real difference in the ways that women are diagnosed and treated, because survival could be predicted more accurately, and treatment tailored more precisely.

- read the press release
- see the abstract
- check out the article on the BBC website