Simple blood test can predict which breast cancer treatment will work best, study finds

The Guardian - World NewsCenter-LeftEN 4 min read 100% complete by Andrew Gregory Health editorJanuary 18, 2026 at 04:26 PM

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A new DNA blood test developed by researchers at the Institute of Cancer Research in London can predict how well breast cancer patients will respond to treatment. The test analyzes circulating tumor DNA (ctDNA) in blood samples to determine the likelihood of a patient's response to a specific treatment, even before it begins. In a study of 167 patients with advanced breast cancer, low levels of ctDNA at the start of treatment and after four weeks were strongly associated with positive treatment response. This early prediction allows doctors to avoid ineffective treatments and offer alternative options, such as targeted therapy, drug combinations, or clinical trials, potentially improving patient outcomes. Clinical trials are underway to assess whether adapting treatment based on these blood tests improves patient outcomes.

Key Entities & Roles

Key Player Opposition Context

UK 50% Breast Cancer Now 60% Royal Marsden NHS foundation trust 60% Cancer Research UK 70% Dr Iseult Browne 70% Institute of Cancer Research, London (ICR) ×380%

Keywords

breast cancer 100% blood test 90% treatment response 80% circulating tumour dna 70% liquid biopsy 60% ctdna 60% cancer treatment 50% clinical trial 40%