Poster Presentation Advances in Neuroblastoma Research Congress 2016

Importance of quality assurance in radiotherapy for optimal local control. A report from the SIOPEN radiotherapy committee of the High Risk Neuroblastoma Trial (HR-NBL1/SIOPEN) (#206)

Tom Boterberg 1 , Karin Dieckmann 2 , Mark N Gaze 3 , Bela Malinova 4 , Henriette Magelssen 5 , Henry Mandeville 6 , Evgenia Glogova 7 , Domonique Valteau-Couanet 8 , Ruth Ladenstein 7
  1. Ghent University Hospital, Ghent, Belgium
  2. General Hospital Vienna, Medical University Vienna, Vienna, Austria
  3. University College London Hospitals, London, UK
  4. University Hospital Motol, Prague, Czech Republic
  5. Oslo University Hospital, Oslo, Norway
  6. The Royal Marsden NHS Foundation Trust, Sutton, UK
  7. Children’s Cancer Research Institute, St. Anna Hospital, Vienna, Austria
  8. Gustave Roussy, Paris, France
Background: Local control plays an important role in high risk metastatic and MYCN-amplified (MNA) localized neuroblastoma, as part of the multimodality treatment approach. In a subset of 100 patients with complete imaging and radiotherapy (RT) data sets treated in the current HR-NBL1/SIOPEN trial, we previously reported on the radiotherapy quality assurance (RTQA), identifying unjustified deviations in 17% of patients. The majority of these were an inappropriate target volume and/or an inappropriate dose. Methods: The aim of this analysis was 1) to investigate local control and event-free survival (EFS) in the full cohort of 1467 patients (stage 4: 1180, MNA: 170, unknown: 117) having received irradiation according to the HR-NBL1/SIOPEN trial recommendation after high dose chemotherapy and autologous stem cell reinfusion between 2002-2015. 2) to correlate local control with RTQA in the subset of 100 patients with previously performed RTQA. Results: In the group of 1467 patients no difference was detected neither in the cumulative incidence of local relapse nor in event-free survival between patients receiving < 21Gy, 21Gy as prescribed or > 21Gy. However, only in the subgroup of 170 patients with localized MNA disease a trend towards improved 5-year EFS was observed in patients receiving 21Gy as prescribed in contrast to those patients who did not (5yr-EFS:70% versus 62%). In the subset of 100 patients with previous RTQA a significantly increased local recurrence rate of 44% (10/23pts) was found when RT had not been delivered according to protocol in contrast to 22% (17/77pts) in patients treated with correct volume and dose (p=0,042). Conclusion: These early results show the importance of RTQA for local control in the treatment of neuroblastoma. Further confirmation in a larger patient population is currently being performed. Prospective central validation of RT planning prior to RT delivery could improve overall disease control.