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Radiation Dose Rate, Biologically Effective Dose, and Tumor Characteristics on Local Control and Toxicity After
Conrad Josef Villafuerte1, David B Shultz1, Normand Laperriere1
1Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.
World Neurosurgery
|June 7, 2021
Summary
Stereotactic radiosurgery dose and biologically effective dose (BED) did not impact acoustic neuroma tumor control. However, salvage stereotactic radiosurgery (SRS) and larger tumors increased local failure, while cystic tumors decreased it.
Area of Science:
- Neurosurgery
- Radiation Oncology
- Oncology
Background:
- Acoustic neuromas require effective treatment to prevent tumor growth and neurological deficits.
- Stereotactic radiosurgery (SRS) is a key modality for acoustic neuroma management.
- Understanding factors influencing treatment outcomes is crucial for patient care.
Purpose of the Study:
- To investigate the relationship between radiation dose parameters and clinical factors with tumor control after SRS for acoustic neuroma.
- To assess the impact of calibration dose rate and biologically effective dose (BED) on local failure (LF) and edema.
- To identify predictors of treatment success and adverse events.
Main Methods:
- Retrospective analysis of 607 patients with acoustic neuromas treated with cobalt-60 SRS (2005-2019).
- Calculation of nominal dose rate and SRS-specific BED using a monoexponential model.
- Statistical analysis to evaluate associations between dose, BED, clinical factors, and outcomes (LF, edema).
Main Results:
- No association was found between dose rate or BED and local failure, radiologic edema, or symptomatic edema.
- Cystic tumors showed a lower LF rate (adjusted hazard ratio 0.26, P = 0.028).
- Salvage SRS for growing tumors was associated with a higher LF rate (adjusted hazard ratio 4.9, P < 0.0001).
- Larger tumor diameter correlated with higher LF, while larger tumor volume correlated with increased edema.
Conclusions:
- Radiation dose metrics (dose rate, BED) did not significantly influence acoustic neuroma control or edema post-SRS.
- Salvage SRS and larger tumor size are risk factors for local failure.
- Cystic tumors appear to have a better prognosis regarding local failure.
- Patient counseling regarding risks associated with larger tumors is recommended.
