Herbert A, Rafiq M, Pham TM, et al. - The findings, based on evidence from more than 1.9 million patients presenting in primary care, provide estimated positive predictive values (PPVs) that could be used to guide specialist referral decisions, taking into account the PPVs of common abdominal symptoms for cancer as well as those for inflammatory bowel disease (IBD) and their composite outcome (cancer or IBD), taking into account the variable PPV. Assessing the risk of cancer and IBD together can help with decision-making and prompt diagnosis of both conditions, reducing the need for specialist referrals or investigations, especially in women.

• Across all studied symptoms, the risk of cancer diagnosis and the risk of IBD diagnosis were of comparable magnitude, especially in women and younger men.

• Estimated PPVs were greatest for change in bowel habit in men and rectal bleeding in women, and lowest for dyspepsia.

• In terms of PPVs for specific cancers, change in bowel habit and rectal bleeding had the highest PPVs for colon and rectal cancer, dysphagia for esophageal cancer, and abdominal bloating/distension (in women) for ovarian cancer.

• Non-abdominal cancer sites had the highest PPVs for abdominal pain (either sex) and abdominal bloating/distension (men only).

• For diagnosis of either cancer or IBD, PPVs of rectal bleeding exceeded the National Institute of Health and Care Excellence-recommended specialist referral threshold of 3% in all age-sex strata, as did PPVs of abdominal pain, change in bowel habit, and dyspepsia, in those aged 60 years and up.

• One of the study's limitations is its reliance on the accuracy and completeness of symptom and disease outcome coding.