01 Aug Common Blood Tests May Help Doctors Detect Unknown Cancers in Patients with Vague Symptoms

MedicalResearch.com Interview with:

Dr. Meena Rafiq

Dr Meena Rafiq | Academic GP & Clinical Research Fellow
FRACGP MRCGP MBBS BSc MSc
Epidemiology of Cancer and Healthcare Outcomes (ECHO) Group, UCL
Department of General Practice, The University of Melbourne
UCL Department of Behavioural Science and Health

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Almost all patients with cancer will first see their GP with symptoms and half of these patients will have vague, non-specific symptoms. As a GP I know it can be challenging to pick up patients with possible cancer in a 10 minute GP appointment, especially if they have vague non-specific symptoms. We know that many of these patients are already having blood tests done by their GP. So, we wanted to see if any of these blood tests could be used to help pick up with patients who see their GP with vague abdominal symptoms like abdominal pain and bloating are most likely to have cancer and need to be urgently referred.

MedicalResearch.com: Which tests were most helpful?

Response:  We found abnormal results in 19 blood tests that are commonly used in primary care that increased the risk of having as-yet-undetected cancer. These included components of the full blood count, inflammatory markers, measures of renal or liver function and bone profile tests. The risk of cancer varied depending on the age and sex of the patient and whether they presented with abdominal pain or bloating. In addition to tumour markers for prostate (PSA) and ovarian (CA125) cancer, the blood tests which were more helpful in detecting cancer were raised platelets, low albumin, anaemia and raised inflammatory markers.

For example, the background risk of cancer in patients who see their GP with abdominal pain or bloating is 2.2%. In females with abdominal bloating this rises up to 25% if they have a raised ovarian tumour marker (CA125), but more importantly it rises up to 12% for other blood test abnormalities (increasing to 12% with a low albumin, 10% with raised platelets, 7% with raised ALP (liver function test) and 6% with anaemia or raised inflammatory markers.

These blood test results will be most informative in women aged 30-59 who wouldn’t be referred based on their symptoms alone. For example, in women aged 50 to 59 with abdominal bloating, the background cancer risk of 1.6% increases to 10% if they have a raised ferritin, to 9% with low albumin, to 8% with raised platelets, to 6% with raised inflammatory markers and to 4% with anaemia.

MedicalResearch.com: What cancers were the blood tests most useful at detecting?

Response: We provided rankings of which cancers were most likely with each abnormal blood test result to help doctors decide which speciality to refer patients to or which investigations to order next. In males the most common cancers to consider are bowel and pancreatic cancers and in females it was bowel, ovarian and pancreatic cancers. 

MedicalResearch.com: What should readers take away from your report?

Response: Commonly used GP blood test results can improve the detection of underlying cancer in patients who see their GP with non-specific abdominal symptoms and can provide an efficient, affordable and readily available solution to diagnosing cancer earlier.

• Patients aged 60 and over seeing their GP with new onset abdominal pain or bloating should be considered for an urgent cancer referral, regardless of blood test results or having other symptoms
• In patients aged under 60 with these symptoms who have blood tests done, GPs should use the results to identify which patients are likely to have cancer to refer them urgently.

MedicalResearch.com: What impact could these findings have on cancer detection?

Response: We know that patients who are diagnosed through urgent cancer pathways have better outcomes and are more likely to be diagnosed earlier. For every 1000 patients who sees their GP with abdominal bloating, adding information from GP blood tests would result in 63 additional urgent cancer referrals and would identify 3 extra cancer patients through this route (a 16% relative increase).

Workload in general practice has been progressively increasing. Most GP appointments are 10 minutes long and it can be challenging to pick up patients with possible cancer, especially if they have vague non-specific symptoms. We hope that our findings can help GPs to pick up patients with vague abdominal symptoms who have cancer easier and diagnose them earlier to improve their outcomes.

MedicalResearch.com: What recommendations do you have for future research as a results of this study?

Response: As we have identified 19 abnormal blood test results that increase the risk of having cancer, and the risks differ depending on the age and sex of the patient,  we hope to in the future build this information into a tool that can be integrated into existing GP computer systems to flag patients who see their GP with these symptoms who are most likely to have cancer and should be considered for an urgent cancer referral.

Citation: Predictive value of abnormal blood tests for detecting cancer in primary care patients with nonspecific abdominal symptoms: A population-based cohort study of 477,870 patients in England
Meena Rafiq , Cristina Renzi, Becky White, Nadine Zakkak, Brian Nicholson, Georgios Lyratzopoulos, Matthew Barclay
Published: July 30, 2024 PLOS Medicine

The paper can be found at https://doi.org/10.1371/journal.pmed.1004426

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Last Updated on August 2, 2024 by Marie Benz MD FAAD