Evidence suggests that a new diagnostic blood test is able to detect cancer and identify metastatic disease in patients with nonspecific symptoms

Cancer cells illustration_Design Cells_208548344

A new type of diagnostic blood test has been shown to accurately detect cancer in patients with nonspecific symptoms, such as unexplained weight loss and fatigue, as well as differentiating between patients with localised and metastatic disease.

This makes it the first blood-based cancer test to determine the metastatic status of a cancer without prior knowledge of the primary cancer type.

In a study published this week in the journal Clinical Cancer Research, researchers from the University of Oxford analysed blood samples from 300 patients with nonspecific but concerning symptoms of cancer using a technique called nuclear magnetic resonance (NMR) metabolomics.

Unlike conventional blood-based tests for cancer, which look for genetic material from tumours, the NMR-based technique uses magnetic field and radio waves to analyse levels of metabolites in the blood as biomarkers to distinguish between different cancer states.

Dr James Larkin, one of the study’s authors, explained: ‘Cancer cells have unique metabolomic fingerprints due to their different metabolic processes. We are only now starting to understand how metabolites produced by tumours can be used as biomarkers to accurately detect cancer.’

NMR-based metabolomic analysis correctly detected the presence of solid tumours in 19 out of 20 patients with cancer in the study. It also identified metastatic disease in these patients with an accuracy of 94%.

The authors emphasise that the techniques will need testing in a larger cohort of patients to confirm the results and evaluate the utility of the test in a wider clinical context.  

But the technique shows promise as a rapid and inexpensive test to enable early detection of cancers in patients before conventional imaging is performed. It could also allow doctors to more promptly identify patients who can benefit from drugs designed to treat metastatic disease.

Rapid diagnostic pathways

NMR metabolomic testing may be particularly helpful for diagnosing cancer in people with vague or nonspecific signs and symptoms, such as unexplained fatigue or weight loss, persistent nausea, or new atypical pain.

Current cancer referral pathways rely on organ-specific symptoms such as haemoptysis or haematuria, or clinically palpable abnormalities such as breast lumps. If symptoms are nonspecific, it can be difficult to know to which specialist a patient should be referred. Patients can go back and forth between GP and hospital many times before a diagnosis is made.

NHS Rapid Diagnostic Centres are being rolled out across England to speed up cancer diagnosis and provide a referral pathway for patients who might not otherwise qualify for urgent referral. But cancer can still be difficult to diagnose without organ-specific symptoms to direct investigations.

Metabolomic testing has the potential to offer a quick and easy-to-administer way to triage patients with more vague signs and symptoms without needing to pinpoint a specific site, allowing doctors to prioritise those patients who require more invasive investigations.

Dr Fay Probert, lead researcher on the Oxford study, said: ‘This work describes a new way of identifying cancer. The goal is to produce a test for cancer that any GP can request.’

‘We envisage that metabolomic analysis of the blood will allow accurate, timely, and cost-effective triaging of patients with suspected cancer, and could allow better prioritisation of patients based on the additional early information this test provides on their disease.’

This article originally appeared on Medscape, part of the Medscape Professional Network.

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