A simple blood test could provide a more effective way to test for early signs of breast cancer than using an X-ray to spot a lump, researchers have said.
Scientists hope the blood test will be more accurate than mammograms, and will also be able to detect whether breast cancer patients are likely to relapse and what drugs their particular type of tumour will respond to.
A new clinical study is about to begin in the UK's largest breast screening clinic at Charing Cross Hospital, west London.
If the trial is successful, women could have a simple blood test every year rather than breast screening.
Researchers will compare the DNA markers in the blood of women with and without breast cancer.
Professor Charles Coombes, co-investigator and Cancer Research UK's breast cancer expert from Imperial College London, said: "When a woman has breast cancer we can tell by the DNA in their blood. But what we're trying to find out in our study is how early the signs of breast cancer show up in a blood test. So by looking at blood samples of women who have breast cancer diagnosed through screening we can see if the cancer is already showing in their blood.
"Our research team is only looking at breast cancer, but there are a number of other projects that are looking at using a blood test to detect other cancers such as bowel and lung."
Dr Jacqui Shaw, principal investigator from the University of Leicester, said: "This exciting research means we could one day have a blood test that detects the very early signs of cancer, meaning women could have an annual blood test rather than breast screening.
"This would remove any worry and anxiety for women who are called for further investigations after a mammogram only to find they don't have cancer.
"As things stand we aren't able to monitor breast cancer patients after they've had surgery and treatment - which is like treating diabetes but not measuring blood sugar levels. This new blood test could change that."
Kate Law, director of clinical research at Cancer Research UK, said she hoped the blood test could become "standard practise on the NHS" in "the not too distant future".
Dr Rachel Greig, senior policy officer at Breakthrough Breast Cancer, said: "We welcome new tests that could be used to detect initial changes associated with the development of breast cancer as we know early diagnosis saves lives.
"However, this study has only just begun so more work is needed before we'll know if a routine blood test like this can become a reality for patients."
:: The study is funded by Cancer Research UK in collaboration with the University of Leicester and Imperial College London.