A new study has identified that breast cancer can be several genetically distinct diseases, each with a different risk of coming back after treatment

WASHINGTON – New research published in the journal Nature shows that breast cancer is 11 genetically distinct diseases, and each has a different prognosis and chance of coming back after treatment.

“Treatments for breast cancer have improved dramatically in recent years, but unfortunately for some women, their breast cancer returns and spreads, becoming incurable. For some, this can be many years later – but it’s been impossible to accurately predict who is at risk of recurrence and who is all clear,” said Carlos Caldas, professor of cancer medicine at the Cancer Research UK Cambridge Institute and leader of the study.

The study, which was also jointly led by Stanford University in California, examined genetic changes in breast tumors from 2 000 women, following them over 20 years to see whether or not the cancer returned. They then analyzed this data to create a tool that can be used in the future to predict which women are likely to be at high risk of relapse.

“In this study, we’ve delved deeper into breast molecular subtypes so we can more accurately identify who might be at risk of relapsing and uncover new ways of treating them,” said Caldas.

Previous research by the group showed that by analysing the DNA of breast cancers, they can actually be considered to be 11 distinct diseases. For example, triple-negative breast cancer, which has one of the worst prognoses, can actually be considered to be two different types of breast cancer. One of these subgroups has an initially poor prognosis, but if successfully treated, the disease is unlikely to come back in those who survived five years post-diagnosis.

Conversely, they also found a group of patients with estrogen-receptor positive tumors who generally have a more favorable initial prognosisthan those with triple-negative, but have a higher risk of a very late relapse of disease up to 20 years post-diagnosis.

It is hoped that stratifying breast cancer patients in this more detailed way could lead to better personalized medicine approaches, reducing the number of people who relapse as well as reassuring those with a very low risk of relapse. But the test is not yet widely available.

“We’re still a way off being able to offer this type of detailed molecular testing to all women, and we need more research to understand how we can tailor treatments to a patient’s individual tumor biology. But this is incredibly encouraging progress,” said Professor Karen Vousden, Cancer Research UK’s chief scientist.

The team is currently developing an affordable test for use in hospitals and investigating better personalized treatment options for breast cancer patients based on their findings. They hope to eventually run clinical trials using the test to stratify women onto better treatment protocols fitting the precise genetic makeup of their tumors. Forbes