New Blood Test Enables Early Cancer Detection in “Low-Risk, but Not No-Risk” Patients

Scientists in the UK say they have developed a blood test that may help detect cancer in people with nonspecific signs and symptoms. The new blood test may enable early cancer detection of a low-risk patient group that is currently unlikely to be diagnosed at an early stage where intervention and treatment can contain the spread of the disease.

The diagnostic challenge

Detecting cancer in the early stages is critical for improving patient outcomes. Current cancer diagnosis and referral pathways are designed predominantly around organ-specific symptoms or clinically palpable abnormalities, such as breast lumps or abdominal masses. The problem is that there is no pathway for patients who present with nonspecific symptoms like fatigue or unexpected weight loss that may be associated with cancer. In many instances, these patients will undergo examination by their general practitioner (GP) physician who may not detect the cancer and instead advise the patient to come back later if the symptoms worsen. The result is that patients in this so-called “low-risk, but not no-risk” group go undiagnosed and miss out on the crucial benefit of early intervention. Often, by the time they do get diagnosed, their cancer is advanced. While it is difficult to determine how many individuals fall into this low-risk, but not no-risk group, the numbers are probably in the range of “tens of thousands of patients across the UK,” according to Dr. James Larkin of the University of Oxford, one of the scientists involved in developing the new blood test. If validated, the test would open a new cancer diagnosis pathway for patients who come to their GP with nonspecific signs and symptoms.

The new blood test     

A Suspected CANcer (SCAN) referral pathway from primary care to the hospital for patients exhibiting nonspecific symptoms has been established in the Oxfordshire region of the UK. All patients referred to SCAN undergo a contrast-enhanced CT of the chest, abdomen, and pelvis, and blood biochemistry and hematology analysis at a multidisciplinary diagnostic center (MDC). If an obvious pathology is not detected on initial investigation, consultant physicians review the patient and attempt to reach a diagnosis The new blood test follows a different and simpler approach based on biofluid metabolomics and utilizes a technology called nuclear magnetic resonance (NMR) spectroscopy that profiles the levels of small molecules called metabolites in the blood. Explanation: Healthy individuals have different metabolic “fingerprints” to those with localized or metastatic cancer. Biofluid metabolomics can identify these fingerprints relying on the simultaneous determination of the levels of small-molecule constituents within a biological sample, which are analyzed to establish disease-specific patterns. NMR spectroscopy or mass spectrometry is used to produce the metabolomic profiles. The effectiveness of the new test in early cancer diagnosis of patients with nonspecific symptoms is documented in a study published in the journal Clinical Cancer Research on January 4, 2022. Dr. Larkin and his research colleagues analyzed samples from 304 patients with nonspecific but concerning symptoms of cancer, such as fatigue and weight loss. They found that the test correctly detected cancer in 19 out of every 20 of the patients who had the disease. While it cannot yet identify the type of tumor a patient has, the test showed 94 percent accuracy in distinguishing between patients with localized or metastatic cancer, making it the first blood test capable of detecting whether a cancer has spread without knowing the type of tumor the patient has. Making the test capable of pinpointing tumor type remains a crucial goal. The test still needs to be validated. The Larkin team plans to confirm the accuracy of the test in a larger cohort of 2,000 to 3,000 British patients with nonspecific symptoms, hopefully within the next two years. Once test accuracy is confirmed, they will seek regulatory approval.

Takeaway

The UK study demonstrates that applying NMR metabolomics to a small blood sample may provide a pathway for investigating low-risk, but not no-risk patients with nonspecific symptoms that may be signs of cancer, a cohort that has traditionally been difficult to diagnose. According to the study authors, the test is sensitive, specific, and inexpensive, requiring nothing more than a blood sample in the clinic and an inexpensive NMR analysis.