(HealthDay) -- Surgery alone results in high five-year event-free and overall survival (EFS and OS) rates for patients with low-risk stage 2a and 2b neuroblastoma (NBL), according to research published online April 23 in the Journal of Clinical Oncology.

To investigate whether surgery alone would achieve three-year OS of ≥95 percent, Douglas R. Strother, M.D., of the University of Calgary in Canada, and colleagues conducted a study involving 915 patients (younger than 22 years) with asymptomatic International Neuroblastoma Staging System stages 2a and 2b NBL who had undergone maximally safe resection of tumor. Patients who had or who were at risk for developing symptomatic disease, those with less than 50 percent tumor resection at diagnosis, or those with unresectable progressive disease following surgery, were treated with chemotherapy.

The researchers found that the five-year EFS was 89 percent, and five-year OS was 97 percent. Five-year EFS was 87 percent and OS was 96 percent for patients with asymptomatic stage 2a or 2b disease. OS was significantly lower for stage 2b patients with unfavorable histology, diploid tumors, or who were aged 18 months or older. The five-year OS rates were 99 and 91 percent for those with stage 1 and 4s NBL, respectively. Five-year OS was 98 percent for patients who required chemotherapy at diagnosis. Recurrence or disease progression was experienced by 11.1 percent of patients observed after surgery.

"Excellent rates can be achieved in asymptomatic low-risk patients with stages 2a and 2b NBL after alone," the authors write. "Immediate use of chemotherapy may be restricted to a minority of with low-risk NBL."