Natural course of neuroblastoma detected by mass screening: s 5-year prospective study at a single institution.

PURPOSE: To describe various favorable courses of neuroblastoma (NBL) detected by mass screening and to present our observation program as a temporary treatment option, to be used until a final decision is made regarding the mass screening program for 6-month-old infants. PATIENTS AND METHODS: Between October 1993 and November 1999, 26 of 51 patients with NBL detected by mass screening were enrolled in our observation program. The criteria for observation included urinary vanillylmandelic acid (VMA) and homovanillic acid (HVA) levels less than 50 microg/mg creatinine, smaller tumor size (< 5.0 cm), preoperative status, and granted informed consent. Patients were divided into four groups according to changes in urinary VMA and HVA values and tumor size. Patients who no longer fulfilled criteria underwent surgery. RESULTS: The observation period ranged from 4 to 73 months. Urinary VMA and HVA levels decreased in 19 of 26 patients, often by age 16 months. Eighteen patients had regressing tumors, and in 10 of these cases, the tumor was undetectable or barely detectable by imaging techniques. Four patients younger than 12 months had increased tumor marker levels and tumor volume, histologically reflecting neuroblastic proliferation. The remaining three patients, all older than 18 months, had varied tumor marker levels but increased tumor volume, histologically reflecting an increase in Schwann cells. No upgrading of tumor stage or unfavorable biologic factor was noted in any patient. CONCLUSION: None of our patients showed evidence of transition from favorable to unfavorable prognosis, a finding that points to a reduction in the significance of screening as a public health measure. Until results of ongoing screening trials involving older patients have been evaluated, the observation program can be used as a temporary measure to avoid, with little risk, unnecessary surgical intervention.