Outcome after Radiotherapy for Vestibular Schwannomas (VS)—Differences in Tumor Control, Symptoms and Quality of Life after Radiotherapy with Photon versus Proton Therapy

SIMPLE SUMMARY: The standard of care for radiotherapy of symptomatic or progressive vestibular schwannomas (VS) is photon beam single-dose radiosurgery (applying 1 × 12 Gy) or (hypo)fractionated radiotherapy (applying 3 × 6 Gy up to 32 × 1.8 Gy). Only few centers also enable irradiation with protons. Proton therapy offers unique physical properties whereby healthy tissue around the tumor can be protected although a very high dose is applied to the target lesion. In patients with benign brain tumors such as vestibular schwannomas reduction of treatment-related side effects is very important. Few data comparing photon vs. proton beam radiotherapy for patients with VS are available. Thus, a detailed evaluation of differences in tumor control, symptoms and quality of life in patients with VS after photon beam vs. proton beam radiotherapy is needed. ABSTRACT: Background: To evaluate differences in local tumor control (LC), symptoms and quality of life (QOL) of 261 patients with VS after stereotactic radiosurgery/hypofractionated stereotactic radiotherapy (SRS/HFSRT) vs. fractionated radiotherapy (FRT) vs. fractionated proton therapy (FPT) were studied. Methods: For SRS/HFSRT (n = 149), the median fraction dose applied was 12 Gy. For FRT (n = 87) and FPT (n = 25), the median cumulative doses applied were 57.6 Gy and 54 Gy (RBE), respectively. FRT and FPT used single median doses of 1.8 Gy/Gy (RBE). Median follow-up was 38 months. We investigated dosimetry for organs at risk and analyzed toxicity and QOL by sending out a questionnaire. Results: LC was 99.5% at 12 months after RT with no statistical difference between treatment groups (p = 0.19). LC was significantly lower in NF2 patients (p = 0.004) and in patients with higher tumor extension grade (p = 0.039). The hearing preservation rate was 97% at 12 months after RT with no statistical difference between treatment groups (p = 0.31). Facial and trigeminal nerve affection after RT occurred as mild symptoms with highest toxicity rate in FPT patients. Conclusion: SRS/HFSRT, FRT and FPT for VS show similar overall clinical and functional outcomes. Cranial nerve impairment rates vary, potentially due to selection bias with larger VS in the FRT and FPT group.