Conrad Josef Villafuerte1, David B Shultz1, Normand Laperriere1, Fred Gentili2, Robert Heaton1, Monique van Prooijen1, Michael D Cusimano3, Mojgan Hodaie2, Michael Schwartz4, Alejandro Berlin1, David Payne1, Suneil K Kalia2, Mark Bernstein2, Justin Wang2, Gelareh Zadeh2, Julian Spears5, Derek S Tsang6. 1. Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network - 610 University Avenue, Toronto, Ontario, Canada M5G 2M9. 2. Division of Neurosurgery, Toronto Western Hospital, University Health Network - 399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8. 3. Division of Neurosurgery, Toronto Western Hospital, University Health Network - 399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8; Division of Neurosurgery, St. Michael's Hospital, Unity Health Toronto - 30 Bond Street, Toronto, Ontario, Canada M5B 1W8. 4. Division of Neurosurgery, Toronto Western Hospital, University Health Network - 399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8; Division of Neurosurgery, Sunnybrook Health Sciences Centre - 2075 Bayview Avenue A131, A-Wing, 1(st) Floor, Toronto, Ontario, Canada M5N 3M5. 5. Division of Neurosurgery, St. Michael's Hospital, Unity Health Toronto - 30 Bond Street, Toronto, Ontario, Canada M5B 1W8. 6. Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network - 610 University Avenue, Toronto, Ontario, Canada M5G 2M9. Electronic address: derek.tsang@rmp.uhn.ca.
Abstract
OBJECTIVE: The goal of this study was to evaluate the relationships between calibration dose-rate, calculated biologically effective dose (BED) and clinical factors on tumor control after stereotactic radiosurgery (SRS) for acoustic neuroma (AN). METHODS: We performed a retrospective study of all patients with AN treated with frame-based cobalt-60 SRS at a single institution between 2005-2019. The calibration dose-rate and cobalt-60 half-life were used to calculate the nominal dose rate during treatment. An SRS-specific monoexponential model accounting for treatment time per lesion was used to estimate BED. RESULTS: A total of 607 patients were treated for 612 AN. Median follow-up was 5.0 years. There was no association between dose rate or BED with local failure (LF), radiologic or symptomatic edema. Cystic tumors (adjusted hazard ratio [aHR] 0.26, p = 0.028) were associated with lower LF while use of SRS as salvage treatment for growing tumor (aHR 4.9, p < 0.0001) was associated with higher LF. Larger diameter tumors experienced more LF while larger volume tumors experienced more radiologic/symptomatic edema. CONCLUSIONS: Radiosurgery dose-rate and BED were not associated with tumor control or radiologic/symptomatic edema. Salvage SRS and larger tumors were associated with a higher LF while cystic tumors were associated with lower LF. Patients with larger tumors should be counselled appropriately about potential side effects and when to seek follow-up care.
OBJECTIVE: The goal of this study was to evaluate the relationships between calibration dose-rate, calculated biologically effective dose (BED) and clinical factors on tumor control after stereotactic radiosurgery (SRS) for acoustic neuroma (AN). METHODS: We performed a retrospective study of all patients with AN treated with frame-based cobalt-60SRS at a single institution between 2005-2019. The calibration dose-rate and cobalt-60 half-life were used to calculate the nominal dose rate during treatment. An SRS-specific monoexponential model accounting for treatment time per lesion was used to estimate BED. RESULTS: A total of 607 patients were treated for 612 AN. Median follow-up was 5.0 years. There was no association between dose rate or BED with local failure (LF), radiologic or symptomatic edema. Cystic tumors (adjusted hazard ratio [aHR] 0.26, p = 0.028) were associated with lower LF while use of SRS as salvage treatment for growing tumor (aHR 4.9, p < 0.0001) was associated with higher LF. Larger diameter tumors experienced more LF while larger volume tumors experienced more radiologic/symptomatic edema. CONCLUSIONS: Radiosurgery dose-rate and BED were not associated with tumor control or radiologic/symptomatic edema. Salvage SRS and larger tumors were associated with a higher LF while cystic tumors were associated with lower LF. Patients with larger tumors should be counselled appropriately about potential side effects and when to seek follow-up care.