Irradiation of spinal metastases: should we continue to include one uninvolved vertebral body above and below in the radiation field?

PURPOSE: Historically, the appropriate target volume to be irradiated for spinal metastases is 1-2 vertebral bodies above and below the level of involvement for three reasons: (1) to avoid missing the correct level in the absence of simulation or (2) to account for the possibility of spread of disease to the adjacent level, and (3) to account for beam penumbra. In this study, we hypothesized that isolated failures occurring in the level adjacent to level treated with stereotactic body radiosurgery (SBRS) were infrequent and that with improved localization techniques with image-guided radiation therapy, treatment of only the involved level of spinal metastases may be more appropriate. METHODS AND MATERIALS: Patients who had received SBRS treatments to only the involved level of the spine as part of a prospective trial for spinal metastases comprised the study population. Follow-up imaging with spine MRI was performed at 3-month intervals following initial treatment. Failures in the adjacent (V±1, V±2) and distant spine were identified and classified accordingly. RESULTS: Fifty-eight patients met inclusion criteria for this study and harbored 65 distinct spinal metastases. At 18-month median follow-up, seven (10.7%) patients failed simultaneously at adjacent levels V±1 and at multiple sites throughout the spine. Only two (3%) patients experienced isolated, solitary adjacent failures at 9 and 11 months, respectively. CONCLUSION: Isolated local failures of the unirradiated adjacent vertebral bodies may occur in <5% of patients with isolated spinal metastasis. On the basis of the data, the current practice of irradiating one vertebral body above and below seems unnecessary and could be revised to irradiate only the involved level(s) of the spine metastasis.

Gamma knife radiosurgery for vestibular schwannoma: early hearing outcomes and evaluation of the cochlear dose.

OBJECTIVE: To evaluate the hearing outcomes for a group of unilateral vestibular schwannoma patients treated with gamma knife radiosurgery and to determine if the cochlear radiation dose affects hearing outcome measures. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Vestibular schwannoma patients (n = 33) treated with gamma knife with complete audiometric follow-up. INTERVENTION: Gamma knife radiosurgery and audiometry. MAIN OUTCOME MEASURES: Pure-tone average (PTA), speech discrimination score (SDS), and cochlear radiation dose. RESULTS: The median audiometric follow-up was 24 months, with a range of 6 to 51 months (mean, 24.6 mo; standard deviation [SD], 13.9). Thirty-one patients received a maximum radiation dose of 26 Gy, and 2 received 24 Gy (mean, 25.9 Gy; SD, 0.48). All patients were treated to the 50% isodose line, and the prescription isodose was 13 Gy in 31 patients and 12 Gy in 2 patients (mean, 12.9 Gy; SD, 0.24). Mean pretreatment PTA and SDS were 55.86 dB and 45.70%, respectively. Mean PTA and SDS at last follow-up were 66.55 dB and 39.15%, respectively. The PTA at 6 months (p = 0.003), 12 months (p = 0.004), and last follow-up (p = 0.001) was significantly poorer than the pretreatment PTA. There was no significant difference between pretreatment and follow-up SDS at any time interval. The mean cochlear radiation dose was 5.2 Gy (range, 2.6-8.5 Gy). The median cochlear dose was 4.75 Gy. Fifteen patients received less than the median cochlear dose, and 18 received greater than or equal to the median cochlear dose. The change in PTA from baseline was significantly poorer at 12 months for those patients whose cochlea received 4.75 Gy (p = 0.02) or greater. Stepwise linear regression analysis using the variables of minimum SDS subsequent to baseline SDS versus total cochlear dose revealed a negative correlation (p = 0.012)-as total cochlear dose increased, SDS decreased. CONCLUSION: The PTA was significantly worse after gamma knife radiosurgery, with a mean follow-up of 24.6 months. Higher radiation doses to the cochlear volume negatively impacted hearing outcomes after radiosurgery for this group of vestibular schwannoma patients.

Malignant parotid tumors: presentation, clinical/pathologic prognostic factors, and treatment outcomes.

PURPOSE: To determine the important clinical/pathologic prognostic factors and optimal treatment of malignant parotid tumors. METHODS AND MATERIALS: This study was a retrospective chart review of 163 patients treated for malignant parotid tumors at two institutions. Of the 163 patients, 91 were treated with surgical resection and radiotherapy (RT), 56 were treated with surgery alone, and 13 were treated with RT alone. The median follow-up was 5.1 years (range, 0-37 years). RESULTS: Locoregional recurrence occurred in 37% of surgery-only, 11% of surgery plus RT, and 15% of RT-only patients (p = 0.001, Pearson's chi-square test). Cox proportional hazard multivariate analysis revealed that increasing age and higher stage were each statistically significantly (p < 0.05) associated with a poorer overall 5-year survival and cause-specific survival. Only increasing age and the absence of adjuvant RT were shown in Cox proportional hazard multivariate analysis to impact negatively on local failure-free survival. CONCLUSION: In Cox proportional hazards multivariate analysis, only increasing age and stage were statistically significant prognostic factors for survival. The addition of RT to surgery did not improve overall survival but did reduce locoregional recurrence and improve local failure-free survival.