Frequency of 'warning signs of cancer' in Norwegian general practice, with prospective recording of subsequent cancer.

Early diagnosis of cancer is an important challenge in general practice. Symptoms are the most common starting points. To assess the association between symptoms presented and subsequent cancer. A cohort study of all patients seen consecutively by GPs. Prospective recording of cancer diagnosis, new cancer or new recurrence. Two hundred and eighty-three general practice surgeries and 10 working days. During patient consultations, GPs registered seven focal symptoms and three general symptoms, commonly considered as warning signs of cancer (WSC). Follow-up 6-11 months later with registration of any subsequent diagnosis of cancer was done. Of 51 073 patients, 6321 (12.4%) had recordings of 7704 WSC. During a median follow-up period of 8 months, 263 patients were diagnosed with cancer and 59 of them with recurrence of a previously diagnosed cancer. Of the cancer patients, 106 (40%) had presented one or more WSC during a preceding consultation. Examined symptoms had likelihood ratios for cancer from 1.5 to 8.2 and positive predictive values (PPVs) from 0.8% to 3.8%. Limited to older age groups, PPVs were a little higher. General symptoms were rarely associated with cancer unless a focal symptom had been recorded as well. Multiple symptoms increased the probability of cancer. 12.4% of GP patients presented with WSC. A general symptom may have cancer diagnostic value, but usually, only when it occurs along with a focal symptom. PPV of any single symptom is low, and decisions about referral require additional information.