Faculty Bibliography

An image-guided robotic stereotactic radiosurgery (SRS) system can be used to deliver curative-intent radiation in either single fraction or hypofractionated doses. Medical records for 19 dogs with nonlymphomatous nasal tumors treated with hypofractionated image-guided robotic stereotactic body radiotherapy (SBRT), either with or without adjunctive treatment, were retrospectively analyzed for survival and prognostic factors. Median survival time (MST) was evaluated using Kaplan-Meier survival curves. Age, breed, tumor type, stage, tumor size, prescribed radiation dose, and heterogeneity index were analyzed for prognostic significance. Dogs were treated with three consecutive-day, 8-12 gray (Gy) fractions of image-guided robotic SBRT. Overall MST was 399 days. No significant prognostic factors were identified. Acute side effects were rare and mild. Late side effects included one dog with an oronasal fistula and six dogs with seizures. In three of six dogs, seizures were a presenting complaint prior to SBRT. The cause of seizures in the remaining three dogs could not be definitively determined due to lack of follow-up computed tomography (CT) imaging. The seizures could have been related to either progression of disease or late radiation effect. Results indicate that image-guided robotic SBRT, either with or without adjunctive therapy, for canine nonlymphomatous nasal tumors provides comparable survival times (STs) to daily fractionated megavoltage radiation with fewer required fractions and fewer acute side effects.

INTRODUCTION/BACKGROUND:Prostate-specific antigen (PSA) bounce after brachytherapy has been well-documented. This phenomenon has also been identified in patients undergoing stereotactic body radiation therapy (SBRT). While the parameters that predict PSA bounce have been extensively studied in prostate brachytherapy patients, this study is the first to analyze the clinical and pathologic predictors of PSA bounce in prostate SBRT patients. MATERIALS AND METHODS/METHODS:Our institution has maintained a prospective database of patients undergoing SBRT for prostate cancer since 2006. Our study population includes patients between May 2006 and November 2011 who have at least 18 months of follow-up. All patients were treated using the CyberKnife treatment system. The prescription dose was 35-36.25 Gy in five fractions. RESULTS:One hundred twenty patients were included in our study. Median PSA follow-up was 24 months (range 18-78 months). Thirty-four (28%) patients had a PSA bounce. The median time to PSA bounce was 9 months, and the median bounce size was 0.50 ng/mL. On univariate analysis, only younger age (p = 0.011) was shown to be associated with an increased incidence of PSA bounce. Other patient factors, including race, prostate size, prior treatment by hormones, and family history of prostate cancer, did not predict PSA bounces. None of the tumor characteristics studied, including Gleason score, pre-treatment PSA, T-stage, or risk classification by NCCN guidelines, were associated with increased incidence of PSA bounces. Younger age was the only statistically significant predictor of PSA bounce on multivariate analysis (OR = 0.937, p = 0.009). CONCLUSION/CONCLUSIONS:PSA bounce, which has been reported after prostate brachytherapy, is also seen in a significant percentage of patients after CyberKnife SBRT. Close observation rather than biopsy can be considered for these patients. Younger age was the only factor that predicted PSA bounce.

PURPOSE/OBJECTIVE(S)/OBJECTIVE:Stereotactic body radiation therapy (SBRT) has been shown to have increased local control and overall survival relative to conventional external beam radiation therapy in patients with medically inoperable stage I non-small cell lung cancer (NSCLC). Excellent rates of local control have been demonstrated both in clinical trials and in single-center studies at large academic institutions. However, there is limited data on the experiences of small academic hospitals with SBRT for stage I NSCLC. The purpose of this study is to report the local control and overall survival rates in patients treated with SBRT for stage I NSCLC at Winthrop-University Hospital (WUH), a small academic hospital. MATERIALS/METHODS/METHODS:This is a retrospective review of 78 stage I central and peripheral NSCLC tumors treated between December 2006 and July 2012 with SBRT at WUH. Treatment was given utilizing fiducials and a respiratory tracking system. If the fiducials were not trackable, a spine tracking system was used for tumor localization. CT-based planning was performed using the ray trace algorithm. Treatment was delivered over consecutive days to a median dose of 4800 cGy delivered in four fractions. The Kaplan-Meier method was used to calculate local control and overall survival. RESULTS:The median age was 78.5 years. Fifty-four percent of the patient population was female. Sixty seven percent of the tumors were stage IA, and 33% of the tumors were stage IB. Fifty-three percent of the tumors were adenocarcinomas and 29% were squamous cell carcinomas, with the remainder being of unknown histology or NSCLC, not otherwise specified The 2-year local control rate was 87%, and the 2-year overall survival was 68%. CONCLUSION/CONCLUSIONS:Our findings support that local control and overall survival at a small academic hospital are comparable to that of larger academic institutions' published experiences with SBRT for stage I NSCLC.

PURPOSE/OBJECTIVE:To assess the short term efficacy of Cyberknife stereotactic radiosurgical treatment of trigeminal neuralgia (TN). METHODS:17 consecutive patients with medically or surgically refractory unilateral TN were treated with Cyberknife radiosurgery. Using superimposed CT cisternogram and MR images, the target segment of the trigeminal nerve was consistently defined as a 6 mm length of nerve approximately 2-3 mm distal to the dorsal root entry zone of the brainstem. A radiosurgical rhizotomy was performed with the Cyberknife utilizing a single collimator to deliver an average maximum dose of 73.06 Gy (range 72.91-73.73) to the target. RESULTS:Follow-up data were available for 16 of the 17 patients post-treatment (range 1-27 months, average 11.8 months). Overall, 14 of 16 (88%) patients responded favorably with either partial or complete relief of symptomatology. 11 of these patients were successfully free of all pain at some point in their post-treatment course, with seven patients pain free to the last follow-up visit (average 5.0 months, range 1-13 months). Symptoms recurred in four patients, taking place at 3, 7.75, 9 and 18 months after Cyberknife therapy. Only two patients reported side effects. One patient developed a bothersome feathery dysesthesia while the second patient reported a non-bothersome mild jaw hypoesthesia. There were no substantial complications related to stereotactic radiosurgery. CONCLUSION/CONCLUSIONS:Cyberknife radiosurgery is a viable treatment alternative in patients with TN with competitive efficacy demonstrated in our group of patients while minimizing adverse effects.

Standard radiation therapy for patients undergoing primary chemosensitized radiation for carcinomas of the cervix usually consists of external beam radiation followed by an intracavitary brachytherapy boost. On occasion, the brachytherapy boost cannot be performed due to unfavorable anatomy or because of coexisting medical conditions. We examined the safety and efficacy of using CyberKnife stereotactic body radiotherapy (SBRT) as a boost to the cervix after external beam radiation in those patients unable to have brachytherapy to give a more effective dose to the cervix than with conventional external beam radiation alone. Six consecutive patients with anatomic or medical conditions precluding a tandem and ovoid boost were treated with combined external beam radiation and CyberKnife boost to the cervix. Five patients received 45 Gy to the pelvis with serial intensity-modulated radiation therapy boost to the uterus and cervix to a dose of 61.2 Gy. These five patients received an SBRT boost to the cervix to a dose of 20 Gy in five fractions of 4 Gy each. One patient was treated to the pelvis to a dose of 45 Gy with an external beam boost to the uterus and cervix to a dose of 50.4 Gy. This patient received an SBRT boost to the cervix to a dose of 19.5 Gy in three fractions of 6.5 Gy. Five percent volumes of the bladder and rectum were kept to ≤75 Gy in all patients (i.e., V75 Gy ≤ 5%). All of the patients remain locally controlled with no evidence of disease following treatment. Grade 1 diarrhea occurred in 4/6 patients during the conventional external beam radiation. There has been no grade 3 or 4 rectal or bladder toxicity. There were no toxicities observed following SBRT boost. At a median follow-up of 14 months, CyberKnife radiosurgical boost is well tolerated and efficacious in providing a boost to patients with cervix cancer who are unable to undergo brachytherapy boost. Further follow-up is required to see if these results remain durable.