A DNA blood test predicts which breast-cancer treatment will work best for patients

(Andrew Gregory/ The Guardian) — Scientists have developed a simple DNA blood test that can predict how well patients with breast cancer will respond to treatment.

More than 2 million people globally each year are diagnosed with the disease, which is the world’s most prevalent cancer. Although treatments have improved in recent decades, it is not easy to know which ones will work best for which patients.

Now researchers have designed a liquid biopsy that tells doctors how likely a patient is to respond to a specific treatment, even before it begins. The test has the potential to be gamechanging because it means patients could be offered alternative options, and avoid treatments that won’t help them, boosting their chances of beating the disease.

The test, developed by a team at the Institute of Cancer Research, London (ICR), analyses circulating tumour DNA (ctDNA), which is released into the blood of patients by cancer cells. (…)