Radiotherapeutic management of vestibular schwannomas using size and location-adapted fractionation regimens to maximize the therapeutic ratio

Publication date: Available online 28 October 2016
Source:Practical Radiation Oncology
Author(s): Benjamin G Slane, Uma Goyal, Joel L Grow, Christopher Morrison, Craig R Hullet, John Gordon, Abhay Sanan, Baldassarre Stea
BackgroundWe evaluated and compared the radiographic and clinical outcomes of patients with vestibular schwannomas treated with either single fraction stereotactic radiosurgery (SRS), or five fractions of hypofractionated stereotactic radiotherapy (hSRT), or 25–30 fractions of conventionally fractionated stereotactic radiotherapy (cfSRT).Methods and MaterialsFifty-six patients treated with linac-based SRS(median 12.5Gy), hSRT(25Gy) or cfSRT(median 54Gy) were retrospectively reviewed. Fractionation was based on the size of the tumor, proximity to the brainstem, and potential risk of neurological sequelae. Median follow-up time was 55.2 months.ResultsThe pretreatment median tumor diameter was significantly smaller for SRS (1.14 cm) compared with hSRT(1.7 cm) (p=0.03) and cfSRT(2.0 cm) (p<0.001). The overall local tumor control was 96.4%: 100% SRS, 100% hSRT, and 90% cfSRT(p=0.19). Tumor regression was observed in 53.3% SRS, 76.2% hSRT, and 90% cfSRT(p=0.05). There was less transient expansion of tumors treated with cfSRT(5%) than with SRS(53.3%) or hSRT(28.6%) (p=0.005). The median time to regression was 13.8 months SRS, 14.2 months hSRT, and 5.5 months cfSRT (p=0.34). There was 3.6% incidence of grade 3 trigeminal neuropathy, but there was no grade 3 facial neuropathy.ConclusionsAll three regimens demonstrated similar excellent local control with minimal toxicity. However, the ability of hSRT to treat larger tumors with comparable outcomes to SRS and greater patient convenience when compared to cfSRT, suggest that hSRT may offer the optimal treatment approach.



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