In advanced breast cancer, it can be difficult to assess whether a treatment is working.
Scans are often required, and it can take time before any effect becomes visible.
According to researchers at The Institute of Cancer Research in London, a blood test could help change this.
The blood test measures small amounts of cancer DNA in the bloodstream. The level of this DNA can indicate how active the disease is.
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The advantage is that the test is minimally invasive and can be repeated throughout the course of treatment.
Basis of the study
The study, published in Clinical Cancer Research, is based on the plasmaMATCH trial, which included 167 people with advanced breast cancer.
The patients had different types of cancer and genetic mutations and received treatments tailored to their disease.
Researchers took blood samples before treatment began and again after four weeks.
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They then compared the levels of cancer DNA in the blood with how the disease progressed.
The analysis showed a clear correlation between DNA levels and treatment outcomes.
What the results show
Patients with low or undetectable levels of cancer DNA had better outcomes.
They experienced longer periods without disease progression, and more of them responded positively to treatment.
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According to the researchers, the blood test could be used to assess at an early stage whether a treatment is effective.
This could make it easier to change strategy if the treatment is not working.
The results will now be tested in larger studies, including the SERENA 6 trial, before the method can become a standard part of treatment.
Sources: The Institute of Cancer Research, and Clinical Cancer Research.
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