The results of routine blood tests could be used to speed up cancer diagnoses among patients with abdominal symptoms, according to a recent study published by Rafiq et al in PLOS Medicine.
Background
Most patients who report symptoms of abdominal pain or bloating to their physicians are referred for blood tests. However, it is not known how well these blood tests can predict cancer risk.
“Half of all [patients] with as-yet-undetected cancer will first go to their [physician] with vague symptoms that can be challenging to diagnose. Many of these patients are investigated in primary care with commonly used blood tests that could help to identify which patients are most likely to have underlying cancer and should be prioritized for referral,” explained lead study author Meena Rafiq, MSc, PhD, of the Department of Behavioural Science & Health at the University College London.
Study Methods and Results
In the recent study, investigators used the Clinical Practice Research Datalink to examine the anonymized data of over 450,000 UK patients aged 30 years and older who visited a physician as a result of abdominal pain (n = over 400,000) or bloating (n = over 50,000) between 2007 and 2016. Two-thirds of the patients received blood tests following their appointments.
In 19 commonly used blood tests, the investigators found abnormal results that were linked to a higher risk of being diagnosed with cancer within 1 year. They estimated that taking the abnormal results into account could result in a 16% increase in the number of patients with undiagnosed cancer who receive an urgent referral compared with assessments based on symptoms, age, and sex alone. This translated to an additional 0.6% (n = 6/1,000) of patients who visited their physicians with abdominal symptoms receiving urgent referrals—on top of the 40 patients with cancer who are already urgently referred without using blood test results.
The researchers found that 2.2% (n = 1/50) of the patients who visited their physicians with abdominal pain and 2.2% of those with bloating were diagnosed with cancer over the next 12 months.
In the United Kingdom, current National Institute for Health and Care Excellence (NICE) guidelines recommend that patients should receive an urgent cancer referral if their risk of cancer is higher than 3%. The investigators revealed that the patients aged 60 years and older who were involved in the study had a high enough risk to warrant an urgent cancer referral regardless of their blood test results. For instance, the risk of cancer was estimated to be 3.1% for male patients aged 60 to 69 years with abdominal pain and 8.6% for male patients aged 80 to 89 years with the same symptom. Among female patients in these age groups, the risk was a respective 3.1% and 6.1%.
Additionally, among the patients aged 30 to 59 years with abdominal pain or bloating, the researchers identified several factors that may have been predictive of the risk of undiagnosed cancer—including anemia, low albumin levels, raised platelet levels, abnormal ferritin levels, and increased inflammatory markers. Among female patients aged 50 to 59 with abdominal bloating, a pre–blood test cancer risk of 1.6% increased to 10% with raised ferritin levels, to 9% with low albumin levels, to 8% with raised platelet levels, to 6% with raised inflammatory markers, and to 4% with anemia. Currently, only raised platelet levels and anemia are included in guidelines for cancer referral, which focus on the presence of alarming symptoms and a single organ’s risk of cancer—with limited guidance existing for vague symptoms that could be a sign of cancer in a number of different organs.
The investigators also demonstrated which types of cancers were most common for patients with these symptoms and how risk varied depending on age and sex. Overall, colorectal cancer was the most common cancer type, followed by prostate and pancreatic cancers in male patients and breast and ovarian cancers in female patients.
The investigators noted that the findings on the predictive value of blood tests for cancer could not be extrapolated to other health systems with higher or lower rates of blood test use.
Conclusions
“This research shows these common tests can substantially enhance assessment of cancer risk,” Dr. Rafiq highlighted.
Despite the findings, the investigators cautioned that the incidence of cancer was likely to be higher among the study participants compared with a broader group of individuals experiencing abdominal pain or bloating who would not necessarily visit their physicians or undergo blood tests.
“Our study suggests we can improve cancer detection with blood tests that are already available and that are routinely given to patients with nonspecific symptoms whose cause is unclear. This could be an efficient, affordable way to improve early cancer diagnosis and in some cases increase the likelihood of successful treatment,” underscored Dr. Rafiq. “Given that in practice it may be challenging for [physicians] to interpret a range of blood test data, our study points to the need for an automated tool that could assess cancer risk based on multiple variables,” she concluded.
Disclosure: The research in this study was funded by Cancer Research UK, the National Institute of Health Research, and the International Alliance for Cancer Early Detection—a partnership between the University College London, Cancer Research UK, the Canary Center at Stanford University, the University of Cambridge, the Oregon Health and Science University Knight Cancer Institute, and the University of Manchester. For full disclosures of the study authors, visit journals.plos.org.
