Use of a test diet in screening for neuroblastoma reduces false-positives attributable to food intake

We attempted to reduce false-positives during screening for neuroblastoma using a qualitative urine test by introducing a test diet without foodstuffs known to cause false-positive results. In preliminary in-vivo experiments, intake of contra-indicated foods such as orange juice or banana was shown to result in high percentages of false-positive results several hours after food intake. False-positive results were obtained even after 24 hours among breast-fed infants whose mothers received orange juice. In a controlled field trial the false-positive rate was reduced to 2.84% among 540 infants taking the test diet compared with 5.05% among 9,844 control infants following conventional guidance on contra-indicated foods (p less than 0.05). For comparison, a questionnaire survey of nationwide screening in Japan in 1987 revealed that 66% of the screening centres employed qualitative urine tests, either a Spot or Dip method. False-positive rates, including those due to inappropriate urine collection, ranged from 0.4% to 33.7% (mean 7.1%). Rates ranged from 0.2% to 18.7% (mean 3.4%) in the remaining 34% of screening centres employing a quantitative method with high performance liquid chromatography.