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.

BACKGROUND: Identifying patients presenting with nonspecific abdominal symptoms who have underlying cancer is a challenge. Common blood tests are widely used to investigate these symptoms in primary care, but their predictive value for detecting cancer in this context is unknown. We quantify the predictive value of 19 abnormal blood test results for detecting underlying cancer in patients presenting with 2 nonspecific abdominal symptoms. METHODS AND FINDINGS: Using data from the UK Clinical Practice Research Datalink (CPRD) linked to the National Cancer Registry, Hospital Episode Statistics and Index of Multiple Deprivation, we conducted a population-based cohort study of patients aged ≥30 presenting to English general practice with abdominal pain or bloating between January 2007 and October 2016. Positive and negative predictive values (PPV and NPV), sensitivity, and specificity for cancer diagnosis (overall and by cancer site) were calculated for 19 abnormal blood test results co-occurring in primary care within 3 months of abdominal pain or bloating presentations. A total of 9,427/425,549 (2.2%) patients with abdominal pain and 1,148/52,321 (2.2%) with abdominal bloating were diagnosed with cancer within 12 months post-presentation. For both symptoms, in both males and females aged ≥60, the PPV for cancer exceeded the 3% risk threshold used by the UK National Institute for Health and Care Excellence for recommending urgent specialist cancer referral. Concurrent blood tests were performed in two thirds of all patients (64% with abdominal pain and 70% with bloating). In patients aged 30 to 59, several blood abnormalities updated a patient's cancer risk to above the 3% threshold: For example, in females aged 50 to 59 with abdominal bloating, pre-blood test cancer risk of 1.6% increased to: 10% with raised ferritin, 9% with low albumin, 8% with raised platelets, 6% with raised inflammatory markers, and 4% with anaemia. Compared to risk assessment solely based on presenting symptom, age and sex, for every 1,000 patients with abdominal bloating, assessment incorporating information from blood test results would result in 63 additional urgent suspected cancer referrals and would identify 3 extra cancer patients through this route (a 16% relative increase in cancer diagnosis yield). Study limitations include reliance on completeness of coding of symptoms in primary care records and possible variation in PPVs if extrapolated to healthcare settings with higher or lower rates of blood test use. CONCLUSIONS: In patients consulting with nonspecific abdominal symptoms, the assessment of cancer risk based on symptoms, age and sex alone can be substantially enhanced by considering additional information from common blood test results. Male and female patients aged ≥60 presenting to primary care with abdominal pain or bloating warrant consideration for urgent cancer referral or investigation. Further cancer assessment should also be considered in patients aged 30 to 59 with concurrent blood test abnormalities. This approach can detect additional patients with underlying cancer through expedited referral routes and can guide decisions on specialist referrals and investigation strategies for different cancer sites.

Trends in primary care blood tests prior to lung and colorectal cancer diagnosis-A retrospective cohort study using linked Australian data.

INTRODUCTION: Abnormal results in common blood tests may occur several months before lung cancer (LC) and colorectal cancer (CRC) diagnosis. Identifying early blood markers of cancer and distinct blood test signatures could support earlier diagnosis in general practice. METHODS: Using linked Australian primary care and hospital cancer registry data, we conducted a cohort study of 855 LC and 399 CRC patients diagnosed between 2001 and 2021. Requests and results from general practice blood tests (six acute phase reactants [APR] and six red blood cell indices [RBCI]) were examined in the 2 years before cancer diagnosis. Poisson regression models were used to estimate monthly incidence rates and examine pre-diagnostic trends in blood test use and abnormal results prior to cancer diagnosis, comparing patterns in LC and CRC patients. RESULTS: General practice blood test requests increase from 7 months before CRC and 6 months before LC diagnosis. Abnormalities in many APR and RBCI tests increase several months before cancer diagnosis, often occur prior to or in the absence of anaemia (in 51% of CRC and 81% of LC patients with abnormalities), and are different in LC and CRC patients. CONCLUSIONS: This study demonstrates an increase in diagnostic activity in Australian general practice several months before LC and CRC diagnosis, indicating potential opportunities for earlier diagnosis. It identifies blood test abnormalities and distinct signatures that are early markers of LC and CRC. If combined with other pre-diagnostic information, these blood tests have potential to support GPs in prioritising patients for cancer investigation of different sites to expedite diagnosis.

Clinical activity in general practice before sarcoma diagnosis: an Australian cohort study.

BACKGROUND: Increased time to diagnosis in sarcoma is associated with poor prognosis and patient outcomes. Research is needed to identify whether opportunities to expedite the diagnosis of sarcoma in general practice exist. AIM: To examine pre-diagnostic GP clinical activity before sarcoma diagnosis. DESIGN AND SETTING: An Australian retrospective cohort study using hospital registry data (Australian Comprehensive Cancer Outcomes and Research Database [ACCORD]) linked to two primary care datasets (Patron and MedicineInsight). METHOD: The frequency of general practice healthcare utilisation events (general practice attendances, prescriptions, blood test, and imaging requests) were compared in 377 patients with soft tissue sarcoma (STS) and 64 patients with bone sarcoma (BS) in the year pre-diagnosis. Poisson regression models were used to calculate monthly incidence rate ratios (IRR) for the 24 months pre-diagnosis and estimate inflection points for when healthcare use started to increase from baseline. RESULTS: In the 6 months pre-diagnosis, patients with sarcoma had a median of 3-4 general practice attendances, around one-third had a GP imaging request (33% [n = 21] BS and 36% [n = 134] STS), and approximately one in five had multiple imaging requests (19% [n = 12] BS and 21% [n = 80] STS). GP imaging requests progressively increased up to eight-fold from 6 months before sarcoma diagnosis (IRR 8.43, 95% confidence interval [CI] = 3.92 to 18.15, P<0.001) and general practice attendances increased from 3 months pre-diagnosis. CONCLUSION: Patients with sarcoma have increased GP clinical activity from 6 months pre-diagnosis, indicating a diagnostic window where potential opportunities exist for earlier diagnosis. Interventions to help identify patients and promote appropriate use of imaging and direct specialist centre referrals could improve earlier diagnosis and patient outcomes.

Underlying disease risk among fatigued patients: a population-based cohort study in primary care.

Background Presenting to primary care with fatigue is associated with a wide range of conditions, including cancer, although their relative likelihood is unknown. Aim To quantify associations between new-onset fatigue presentation and subsequent diagnosis of various diseases, including cancer. Design and setting Cohort study of patients presenting in English primary care with new-onset fatigue during 2007-2017 (fatigue presenters (FPs)), compared to non-fatigue presenters (NFPs), using Clinical Practice Research Datalink data linked to hospital episodes and national cancer registration data. Method We described excess short-term incidence of 237 diseases in FPs compared to NFPs. We modelled disease-specific 12-month risk by sex and calculated age-adjusted risk. Results We included 304,914 FPs and 423,671 NFPs. 127 of 237 diseases studied were more common in male FPs than in male NFPs, and 151 were more common in female FPs. Diseases that were most strongly associated with fatigue included: depression; insomnia & sleep disturbances, and hypo/hyperthyroidism (women only). By 80 years, cancer was the 3rd most common disease and had the 4th highest absolute excess risk in male FPs (FPs: 7.0%, CI = 6.6 to 7.5; NFPs: 3.4%, CI = 3.1 to 3.7; AER: 3.7%). In women, cancer remained relatively infrequent; by age 80 it had the 13th highest excess risk in FPs. Conclusion Our study ranks the likelihood of possible diagnoses in fatigue presenters, to inform diagnostic guidelines and doctors' decisions. Age-specific findings support recommendations to prioritise cancer investigation in older men with fatigue, but not women.

Clinical decision-making on lung cancer investigations in primary care: a vignette study.

OBJECTIVES: To investigate the role of comorbid chronic obstructive pulmonary disease (COPD) and symptom type on general practitioners' (GP's) symptom attribution and clinical decision-making in relation to lung cancer diagnosis. DESIGN: Vignette survey with a 2×2 mixed factorial design. SETTING: A nationwide online survey exploring clinical decision-making in primary care. PARTICIPANTS: 109 GPs based in the United Kingdom (UK) who were registered as responders on Dynata (an online survey platform). INTERVENTIONS: GPs were presented with four vignettes which described a patient aged 75 with a smoking history presenting with worsening symptoms (either general or respiratory) and with or without a pre-existing diagnosis of COPD. PRIMARY AND SECONDARY OUTCOME MEASURES: GPs indicated the three most likely diagnoses (free-text) and selected four management approaches (20 pre-coded options). Attribution of symptoms to lung cancer and referral for urgent chest X-ray were primary outcomes. Alternative diagnoses and management approaches were explored as secondary outcomes. Multivariable mixed-effects logistic regression was used, including random intercepts for individual GPs. RESULTS: 422 vignettes were completed. There was no evidence for COPD status as a predictor of lung cancer attribution (OR=1.1, 95% CI=0.5-2.4, p=0.914). There was no evidence for COPD status as a predictor of urgent chest X-ray referral (OR=0.6, 95% CI=0.3-1.2, p=0.12) or as a predictor when in combination with symptom type (OR=0.9, 95% CI=0.5-1.8, p=0.767). CONCLUSIONS: Lung cancer was identified as a possible diagnosis for persistent respiratory by only one out of five GPs, irrespective of the patients' COPD status. Increasing awareness among GPs of the link between COPD and lung cancer may increase the propensity for performing chest X-rays and referral for diagnostic testing for symptomatic patients.