A trial involving a blood test that can detect more than 50 different cancers has shown promising results among thousands of NHS patients in the UK, scientists have announced.
The Galleri test, currently available in the US, is also able to pinpoint from where in the body the disease is coming, with 85% accuracy, reports The Independent.
In the Symplify trial, the test detected cancer in 323 out of the 6 238 people who had visited their GP with suspected symptoms in England or Wales. Of the 323, 244 were subsequently diagnosed with cancer, giving a positive predictive accuracy of 75%, the researchers said.
Around 2% of patients with a negative result were found to have cancer, and overall, the test correctly revealed cancer 66% of the time.
The accuracy of the test was also dependent on the stage of the cancer – ranging from 24% for very early-stage (stage I) tumours to 95% for advanced disease (stage IV). The most common cancer diagnoses were bowel (37%), lung (22%), uterine (8%), oesophago-gastric (6%) and ovarian (4%).
Brian Nicholson, associate professor at the Nuffield Department of Primary Care Health Sciences, University of Oxford, said the findings suggest that multi-cancer early detection tests (MCEDs) can play a role “to confirm symptomatic patients should be evaluated for cancer before pursuing other diagnoses”.
“Most patients diagnosed with cancer first see a primary care physician for the investigation of symptoms, like weight loss, anaemia, or abdominal pain, which can be complex as there are multiple potential causes.
“New tools that can both expedite cancer diagnosis and potentially avoid invasive and costly investigations are needed to more accurately triage patients with non-specific cancer symptoms.”
The Galleri test works by looking for chemical changes in fragments of genetic code – cell-free DNA (cfDNA) – that leak from tumours into the bloodstream.
Some cancer tumours are known to shed DNA into the blood a long time before a person starts having symptoms.
The test does not detect all cancers and does not replace standard NHS screening programmes, like those for breast, cervical and bowel cancer.
In the US, it has been recommended for people at higher risk of cancer, including over-50s.
Developed by Californian company Grail, the test is also being trialled in the NHS to see if it can detect hidden cancers in people without symptoms, with results expected later this year.
Lawrence Young, professor of Molecular Oncology at the University of Warwick, described the results as “very encouraging”.
However, he added: “The current, overall sensitivity of this test remains an issue, particularly for certain types of cancer other than those of the upper gastrointestinal tract.
“The real challenge is to diagnose cancers that are difficult to detect. e.g lung, pancreas, and use a positive blood test to instigate other investigations such as imaging. To really trust that a negative result on blood testing means no cancer will require more studies.”
The findings from the Symplify trial were presented at the American Society of Clinical Oncology conference in Chicago this week, and will be published in The Lancet Oncology journal.
Study details
Large-scale observational prospective cohort study of a multi-cancer early detection (MCED) test in symptomatic patients referred for cancer investigation.
Brian Nicholson, Oke Jason, Dean Harris, Mark Middleton, et al.
Presented at the 2023 American Society of Clinical Oncology meeting (2-6 June) in Chicago
Background
Delays in cancer diagnosis can lead to increased mortality, leading to specialised diagnostic pathways for symptomatic patients when cancer is suspected. Identification of circulating tumour DNA can stratify individuals into those more or less likely to have cancer and predict the cancer origin. This could both expedite cancer diagnosis and reduce harm and inefficient investigation in those who do not have cancer. We evaluated the performance of a next-generation sequencing MCED test (GRAIL, LLC) using cell-free DNA (cfDNA) isolated from whole blood in symptomatic patients referred to cancer diagnostic clinics by their primary care physician.
Methods
Patients referred for urgent imaging, endoscopy or other diagnostic modalities to investigate symptoms suspicious for cancer were invited to take part. Participants with non-specific symptoms or being tested for lung, gynaecological, upper gastrointestinal (GI) or lower GI cancers gave a blood sample on the day they attended for urgent standard of care investigations. cfDNA was isolated from blood samples and stored until the MCED test was performed in batches, blinded to clinical outcome. The test’s predictions (cancer signal detected yes/no; predicted signal origin) were compared with the diagnosis obtained by standard care to establish the positive and negative predictive value (PPV & NPV), sensitivity and specificity across the whole study population, by referral pathway, and by presenting symptom. In addition, sensitivity was analysed by cancer site and stage.
Results
A total of 6238 participants were recruited over five months from the five clinical pathways at 44 hospital sites in England and Wales. 5461 individuals had an MCED test result and diagnostic outcome and were evaluable. Mean age was 62.1 years (SD, 13.8), 3609 (66.1%) female, 2533 (46.4%) current or former smokers. 368 (6.7%) evaluable patients had a cancer diagnosed. The MCED test detected a cancer signal in 323 cases, 244 in whom cancer was diagnosed and 79 where it was not, yielding a PPV of 75.5% (95% CI 70.5-80.1%), NPV 97.6% (97.1-98.0%), sensitivity 66.3% (61.2-71.1%), and specificity 98.4% (98.1-98.8%). Sensitivity increased with increasing age and cancer stage, from 24.2% (16.0-34.1%) in Stage I to 95.3% (88.5-98.7%) in Stage IV. Sensitivity 80.4% (66.1-90.6%) and NPV 99.1% (98.2-99.6%) were highest for patients referred with symptoms qualifying for the upper GI pathway.
Conclusions
This is the first large-scale prospective evaluation of an MCED test in a symptomatic population. These data provide the basis for a prospective, interventional study in patients presenting to primary care with non-specific signs and symptoms with low, but higher than background, probability of being due to cancer. Study data are also being used to enhance the negative predictive value of the current MCED classifier for a symptomatic population.
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