TY - JOUR T1 - The predictive value of cancer symptoms in primary care JF - British Journal of General Practice JO - Br J Gen Pract SP - 639 LP - 640 DO - 10.3399/bjgp10X515304 VL - 60 IS - 578 AU - Kevin Barraclough Y1 - 2010/09/01 UR - http://bjgp.org/content/60/578/639.abstract N2 - GPs are presented, several times a day, with patients with a mass of intertwined symptoms. Many of these symptoms, often matted together like overcooked pasta, could be due to cancer. In practice most of them are not. However, neither GPs nor specialists have the experience to weight these symptoms accurately: GPs because they do not see enough patients with individual cancers, and specialists because they do not see enough patients who are healthy (leading to ‘spectrum bias’1). For this reason ‘gut feeling’, instinct, or previous experience are all relatively blunt discriminators. Secondary care studies are also of limited use. What we really need are numbers from good primary care studies. These are surprisingly few and far between.2,3Shapley et al3 analysed all high-quality primary care studies that identify clinical features that have, in at least one age/sex range, a positive predictive value (PPV) of 5% or more. In justifying their 5% figure they discuss what level of cancer risk should routinely be investigated.The authors identify eight clinical features that predict cancer at the 5% probability level: rectal bleeding, change in bowel habit, iron deficiency anaemia, macroscopic haematuria, a malignant-feeling … ER -