Radiation Therapy to Sites of Metastatic Disease as Part of Consolidation in High-risk Neuroblastoma: Can Long-term Control be Achieved?

Publication date: Available online 9 January 2018
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Dana L. Casey, Ken L. Pitter, Brian H. Kushner, Nai-Kong V. Cheung, Shakeel Modak, Michael P. LaQuaglia, Suzanne L. Wolden
BackgroundAs part of consolidative therapy in high-risk neuroblastoma, modern protocols recommend radiation therapy (RT) both to the primary site and to sites of metastatic disease that persist after induction chemotherapy. Although there is abundant data showing excellent local control with 21 Gy directed at the primary site, there is little data describing the feasibility and efficacy of RT directed at metastatic sites of disease as part of consolidation.MethodsAll patients with neuroblastoma who received RT to metastatic sites of disease as a part of consolidative therapy at a single institution between 2000 and 2015 were reviewed. Among 159 patients, 244 metastases were irradiated.ResultsMedian follow up among surviving patients was 7.4 years. Over 85% of the irradiated metastases were treated with 21 Gy (range 10.5 Gy - 36 Gy). Tumor recurrence occurred in 43 of 244 (18%) irradiated metastases. The 5-year local control (LC) of treated metastatic sites was 81%. Metastatic sites that cleared with induction chemotherapy had improved LC compared to sites with persistent uptake on MIBG (LC 92% vs 67%, p<0.0001). LC at irradiated metastatic sites did not differ based on total number of sites irradiated or site of disease irradiated (bone vs soft tissue). Patients with bulky, resistant disease who were treated with 30-36 Gy had worse LC (p=0.02). However, on multivariate analysis, only persistence after induction chemotherapy remained a significant prognostic factor for LC (hazard ratio = 3.7, p<0.0001). Patients with LC at irradiated metastatic sites had improved overall survival (OS) compared to those who did not (OS 71% vs 50%, p<0.0001).ConclusionsResponse to chemotherapy is an important prognostic factor for LC at irradiated metastatic sites in neuroblastoma. Overall, consolidative RT appears to be an effective modality of LC. Long-term disease control can be achieved with such an approach.

Teaser

Although radiation therapy to persistent sites of metastatic disease is recommended as part of consolidative therapy for high-risk neuroblastoma, there is little data evaluating the value of this approach in achieving long-term control. Our results show that irradiation of metastatic sites of disease is effective in achieving local control, and that response to induction chemotherapy is a significant prognostic factor for control at irradiated sites.


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