Features of childhood cancer in primary care: a population-based nested case–control study

BACKGROUND: This study investigated the risk of cancer in children with alert symptoms identified in current UK guidance, or with increased consultation frequency in primary care. METHODS: A population-based, nested case–control study used data from the General Practice Research Database. In all, 1267 children age 0–14 years diagnosed with childhood cancer were matched to 15 318 controls. Likelihood ratios and positive predictive values (PPVs) were calculated to assess risk. RESULTS: Alert symptoms recorded in the 12 and 3 months before diagnosis were present in 33.7% and 27.0% of cases vs 5.4% and 1.4% of controls, respectively. The PPV of having cancer for any alert symptom in the 3 months before diagnosis was 0.55 per 1000 children. Cases consulted more frequently particularly in the 3 months before diagnosis (86% cases vs 41% controls). Of these, 36% of cases and 9% of controls had consulted 4 times or more. The PPV for cancer in a child consulting 4 times or more in 3 months was 0.13 per 1000 children. CONCLUSION: Alert symptoms and frequent consultations are associated with childhood cancer. However, individual symptoms and consultation patterns have very low PPVs for cancer in primary care (e.g., of 10 000 children with a recorded alert symptom, approximately 6 would be diagnosed with cancer within 3 months).