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).