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A new test that uses heat to examine blood can be used to detect cancer, according to US scientists.

The "plasma thermogram" examines the proteins inside blood, including those produced by tumours.

A study, in the journal Plos One, showed the test could detect cervical cancer and how advanced it was.

Cancer Research UK said thermograms might improve detection, but more evidence on the accuracy and reliability was needed.

Screening for cervical cancer currently involves a looking for abnormal cells in a smear test and detecting high-risk viruses that can cause the disease.

The study, at the University of Louisville, used the plasma thermogram technology to analyse blood samples.

The sample will respond differently to heat depending on the types of proteins contained in the blood. It results in a thermogram - like a fingerprint - of the protein content.

The system was tested on 67 women with different stages of the cervical cancer to see if it could detect the differences between the patients and healthy people.

Lead researcher Dr Nichola Garbett said: "We have been able to demonstrate a more convenient, less intrusive test for detecting and staging cervical cancer."

She said the test could be used to determine which cancers needed to be treated and which needed monitoring.

"Comparing blood samples of patients who are being screened or treated against those thermograms should enable us to better monitor patients as they are undergoing treatment and follow-up," she added.

"This will be a chance for us to adjust treatments so they are more effective."

Dr Emma Smith, from Cancer Research UK, said: "This new approach could lead to improvements in the way we detect, treat and monitor cervical cancer, but this was a very small study so it's not yet known if it will be accurate and reliable enough for wider use.

"Early changes that can lead to cervical cancer often disappear naturally, so having a test that gives doctors a better indication of the risk posed by abnormal cells detected during a smear test could prevent some women receiving unnecessary treatment."