Residual tumor in cases of intermediate-risk neuroblastoma did not influence the prognosis.

Background: It remains unclear whether a residual tumor mass following therapy influences the prognosis of neuroblastoma.

Methods: We retrospectively reviewed 20 patients with intermediate-risk tumors treated at our institution between 1993 and 2012 to elucidate whether additional treatment is required for residual tumors.

Results: The patient ages at diagnosis ranged from 0 days to 7 years. The 5-year overall survival rate was 94.4%. Thirteen patients had Stage 3 disease and seven patients had Stage 4 disease. Nine patients showed intraspinal extension. Twelve patients had a residual tumor mass at the completion of therapy, and eight showed intraspinal extension. Five of these 12 patients showed metaiodobenzylguanidine (MIBG) uptake at the end of treatment, but the uptake disappeared during the follow-up period. Except for one patient who died due to treatment complications, the rest are all alive, and nine are alive with a residual mass. We examined the residual mass in four patients and found that these tissues had differentiated into a ganglioneuroma or changed to a necrotic tissue. For the three patients with neurological symptoms at the end of treatment, some slight neurological symptoms still remained during the follow-up. Five patients with an intraspinal mass eventually presented with new symptoms.

Conclusions: The presence of a residual mass at the end of treatment did not influence the patients' prognosis. Therefore, an invasive radical surgical resection and additional treatment may not be necessary. Cases with a residual intraspinal mass also require a long-term follow-up to assess the neurological prognosis.The presence of a residual mass in cases of intermediate-risk neuroblastoma at the end of treatment did not influence the patients' prognosis.