A prospective study of a long-term follow-up of an observation program for neuroblastoma detected by mass screening.

Background: A nationwide mass screening for neuroblastoma (NBL) in 6-month-old infants (MS6M) was performed in Japan from 1985 to 2003. Favorable biological features were identified for most of the detected tumors; consequently, we began an observation program for selected screened patients in 1993. Here, we report the clinicopathological findings and present status of patients enrolled in our observation program, with the goal of evaluating its usefulness.

Procedure: Between 1993 and 2003, 53 of 101 patients with NBL detected by MS6M were enrolled. The patients were divided into four groups according to changes in urinary VMA and HVA levels and tumor size.

Results: Urinary VMA and HVA levels decreased in 39 of 53 patients. In 17 of these 39 patients, the tumor became undetectable (Group A); in 22 patients the tumor was detectable (Group B). In seven patients, tumor marker levels varied, and tumor volume gradually increased (Group C). In six patients, tumor marker levels and tumor volume increased in the short term (Group D). One patient had multiple tumors (1M according to International Neuroblastoma Staging System). All tumors in Groups C and D, four tumors in Group B, and one tumor in the 1M patient were removed. No unfavorable biologic factors were noted in any excised tumor.

Conclusions: The observation program of the present study, one of the largest series for MS6M, confirmed that over 70% of patients who fulfilled the criteria could be observed without surgery.