Variations in symptoms, endoscopy use and emergency diagnosis of colorectal cancer by body mass index: a retrospective cohort study using linked electronic health records in England

OBJECTIVES: Body mass index (BMI) confers a higher risk of colorectal cancer (CRC) and may influence cancer diagnostic pathways. We investigated variations in diagnostic pathways by BMI category among patients with symptomatic CRC. DESIGN: Retrospective cohort study using linked cancer registry, primary, and secondary care data. SETTING: England PARTICIPANTS: 5571 patients with symptomatic CRC diagnosed in England between 2011 and 2015. PRIMARY AND SECONDARY OUTCOME MEASURES: Route to CRC diagnosis (emergency presentation and fast-track referrals among patients with new-onset red flag symptoms), presenting symptoms and pre-diagnostic endoscopy use. RESULTS: Red-flag symptoms (change in bowel habit, rectal bleeding) were more frequently recorded among patients with rectal cancer with obesity and overweight versus normal weight (65.2% and 65.5% vs 56.8%, respectively). Among colon cancer patients endoscopy during the year pre-diagnosis was used in a greater proportion of patients with obesity versus normal weight (72.8% vs 64.4%, p<0.001). Among patients with colon cancer with red-flag symptoms, being overweight versus normal weight was associated with higher odds of fast-track referral compared with diagnosis through other routes (OR: 1.48, 95% CI 1.16 to 1.88). Obesity was associated with lower odds of emergency presentation, compared with normal weight (colon 23.6% vs 32.1%; adjusted OR: 0.72, 95% CI 0.57 to 0.90; rectum 8.3% vs 14.8%; OR: 0.57, 95% CI 0.35 to 0.92). CONCLUSIONS: Patients with CRC with higher BMI are more likely to be referred urgently and less likely to experience emergency cancer diagnosis than normal weight patients.