A study of more than 275,000 patients found that tracking changes over time across 23 routine tests identified cancer risk more accurately than single abnormal results.
Tracking changes over time in routine blood test results can improve cancer triage among patients presenting with unexplained weight loss, according to a study led by Brian Nicholson and colleagues from the University of Oxford, UK, published in PLOS Medicine.
While abnormal findings on isolated tests—such as elevated platelet counts or low hemoglobin—regularly serve as clinical indicators of potential malignancy, the researchers reported that evaluating repeat testing patterns can detect cancer-related physiological shifts even when individual values remain within normal reference ranges.
The researchers evaluated whether monitoring trends across 26 commonly ordered primary care blood tests could enhance risk stratification compared to relying on single test abnormalities in patients with unexplained weight loss, a non-specific symptom linked to several cancer types.
“We show how blood test results are made more accurate for cancer by adding patient age and sex,” says Brian Nicholson, study author, in a release. “This relatively simple calculation could easily be performed at the laboratory.”
Analyzing Longitudinal Primary Care Data
The cohort study evaluated more than 275,000 primary care patients presenting with unexplained weight loss. Within that cohort, nearly 14,000 patients received a cancer diagnosis within six months, enabling investigators to benchmark single-test anomalies directly against multi-test trajectories over time.
According to the study, 23 blood test trends were associated with overall cancer risk. When adjusted for patient age and sex, multiple longitudinal trends offered greater discriminative power for malignancy than standalone abnormal measurements.
The authors also noted that several trends corresponded to site-specific malignancies. For instance, shifts in white blood cell counts and neutrophils correlated with lung cancer, while progressive changes in red blood cell count, hematocrit, and platelet-to-lymphocyte ratio were linked to prostate cancer.
Implications for Clinical Laboratory Workflows
The findings indicate that clinical laboratories and primary care providers could leverage historical laboratory data alongside age and sex adjustments to flag patients who require expedited diagnostic workups.
“In some instances, monitoring how a patient’s blood test results change over time could offer further value,” says Pradeep Virdee, study author, in a release. “We plan to assess how well blood test abnormalities and trends inform cancer risk in patients with other types of non-specific symptoms, such as fatigue and vomiting.”
According to the study authors, incorporating historical trend models and basic demographic variables into diagnostic triage could help clinicians identify high-risk individuals earlier and target downstream cancer investigations more effectively.
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