CyberKnife Stereotactic Radiotherapy Research Articles

Branch Chain Amino Acid Metabolism Promotes Brain Metastasis of NSCLC through EMT Occurrence by Regulating ALKBH5 activity.

Metabolic reprogramming is one of the essential features of tumors that may dramatically contribute to cancer metastasis. Employing liquid chromatography-tandem mass spectrometry-based metabolomics, we analyzed the metabolic profile from 12 pairwise serum samples of NSCLC brain metastasis patients before and after CyberKnife Stereotactic Radiotherapy. We evaluated the histopathological architecture of 144 surgically resected NSCLC brain metastases. Differential metabolites were screened and conducted for functional clustering and annotation. Metabolomic profiling identified a pathway that was enriched in the metabolism of branched-chain amino acids (BCAAs). Pathologically, adenocarcinoma with a solid growth pattern has a higher propensity for brain metastasis. Patients with high BCAT1 protein levels in lung adenocarcinoma tissues were associated with a poor prognosis. We found that brain NSCLC cells had elevated catabolism of BCAAs, which led to a depletion of α-KG. This depletion, in turn, reduced the expression and activity of the m6A demethylase ALKBH5. Thus, ALKBH5 inhibition participated in maintaining the m6A methylation of mesenchymal genes and promoted the occurrence of epithelial-mesenchymal transition (EMT) in NSCLC cells and the proliferation of NSCLC cells in the brain. BCAA catabolism plays an essential role in the metastasis of NSCLC cells.

Unilateral Multiple Evanescent White Dot Syndrome-Like Reaction Following the CyberKnife Stereotactic Radiotherapy for Choroidal Malignant Melanoma.

A 58-year-old otherwise healthy man received a diagnosis of choroidal malignant melanoma (CMM) in June 2021 and underwent a single session of (21 Gy) CyberKnife stereotactic radiotherapy (SRT). Eleven months later, we noticed 3+ anterior chamber cells with occasional vitreous cells in the left eye. Though the tumor looked regressed, there were mild optic disc leakage, early hypofluorescent and late hyperfluorescent punctate lesions scattered 360 degrees, and late staining of the mass on fluorescein angiogram. The findings were compatible with a unilateral multiple evanescent white dot syndrome (MEWDS)-like reaction that was most likely related to CyberKnife SRT-induced tumor necrosis, and a dexamethasone implant was administered intravitreally into the left eye together with topical steroids. A second intravitreal injection of dexamethasone was given three months later due to remittance of the angiographic features. As there are only a few reports on CyberKnife SRT for the treatment of CMM, we wanted to share our interesting observation of a post-treatment MEWDS-like reaction likely related to tumor necrosis syndrome with the ophthalmic community.

Treatment response in prostatic neoplastic lesions using CyberKnife (stereotactic body radiation therapy)

Objective: To evaluate the treatment response of CyberKnife stereotactic radiotherapy in patients with prostatic neoplastic lesions.Patients and methods: This prospective observational study was conducted at Radiology and Cyberknife Robotic Radiosurgery Department of Jinnah Post Graduate Medical Centre (JPMC), Karachi from 22nd June 2019 to 21st June 2020. Males with biopsy-proven prostatic adenocarcinoma with age 55 years or more having Gleason's score of 6 to 8, clinical stage of T1 to T2C, and prostate-specific antigen (PSA) of ≤30 ng/ml were consecutively enrolled. Detailed information regarding PSA concentration, Gleason score, T stage, risk group and ADT (Androgen Deprivation Therapy) usage were noted which were given to high risk patients only for 9 months. Drop in the PSA (biochemical marker) was assessed at baseline, at 3 months and 6 months follow-up.Results: The median age of the patients was 65 years. The overall median PSA level was 2.7 (0.86-7.3) ng/ml. Majority 49 (90.7%) patients presented with T2 N0 M0 TNM status while only 5 (9.3%) patients presented with T1 N0 M0 TNM status. There were 5 (9.3%) patients with high risk, 26 (48.1%) with intermediate risk, and 23 (42.6%) with low risk. ADT was received by 5 (9.3%) patients. The median PSA at baseline was 10.1 (6.9-18.1) ng/ml which significantly drops to 1.6 (0.8-3.6) ng/ml at 3rd months, and 0.4 (0.2-1.2) at 6th months (p-value <0.01).Conclusion: The findings showed an adequate treatment response of CyberKnife stereotactic radiotherapy of patients with prostatic neoplastic lesions.

Re-irradiation of multiple brain metastases using CyberKnife stereotactic radiotherapy: Case report.

Introduction:Brain metastasis (BM) is the commonest adult intracranial malignancy and many patients with brain metastases require two course radiotherapy. Re-irradiation is frequently performed in Radiotherapy (RT) departments for multiple brain metastases.Patient concerns:We present a case of a 55-year-old male patient suffering from brain metastases, who had previously received whole-brain radiotherapy (WBRT) and first CyberKnife Stereotactic Radiotherapy (CKSRT) for metastases, presented with a recurrence of metastasis and new lesions in the brain.Diagnoses:An enhanced computed tomography (CT) scan of the brain revealed abnormalities with double-dosing of intravenous contrast that identified >10 lesions scattered in the whole brain.Interventions:Re-irradiation was performed using CKSRT. The patient was treated with 30 Gy in 5 fractions for new lesions and 25 Gy in 5 fractions for lesion that were locally recurrent and close to brainstem lesions.Outcome:The lesions were well-controlled, and the headache of the patient was significantly relieved one month after radiotherapy. The total survival time of the patients was 17 months from the beginning of the Cyberknife treatment.Conclusion:The present case report demonstrates that CyberKnife therapy plays a significant role in the repeated radiotherapy for multiple metastatic brain tumors. CKSRT can be used as a salvage method in recurrent multiple brain metastases.

Analysis of factors influencing radiation-induced liver injury caused by stereotactic radiotherapy in patients with primary hepatocellular carcinoma

Objective: To analyze the factors influencing radiation-induced liver injury after receiving Cyberknife stereotactic radiotherapy in patients with primary hepatocellular carcinoma. Methods: 278 cases with primary hepatocellular carcinoma from July 2016 to April 2019 were prospectively enrolled. Stereotactic radiosurgery with a prescription dose of 48-55gy/5-8 times were given. Liver function, coagulation function, Child-Pugh score, and liver imaging changes were dynamically observed before and after treatment to evaluate the occurrence of radiation-induced liver injury. Logistic regression model was used to analyze the factors influencing radiation-induced liver injury. Results: Among 278 cases, 3 cases of tumor progression were excluded, and a total of 275 cases were included for analysis. The overall survival rate after 8 months of treatment was 100%. Among them, 22 cases were diagnosed as radiation-induced liver injury, with an incidence rate of 8%, and all cases were recovered after symptomatic treatment. Multivariate analysis result suggested that the peripheral white blood cell count was factors influencing the occurrence of radiation-induced liver injury. Conclusion: Cyberknife stereotactic radiotherapy has a low incidence of radiation-induced liver injury in patients with liver cancer, and it is a relatively safe treatment method. Patients with low peripheral white blood cell counts before treatment should be closely monitored for early detection and treatment.

Preliminary Analysis of CyberKnife Stereotactic Radiotherapy for Primary and Recurrent Head and Neck Cancers: A Delicate Balance

Preliminary Analysis of CyberKnife Stereotactic Radiotherapy for Primary and Recurrent Head and Neck Cancers: A Delicate Balance

Treatment of Residual, Recurrent, or Metastatic Intracranial Hemangiopericytomas With Stereotactic Radiotherapy Using CyberKnife.

PurposeHemangiopericytomas are aggressive tumors known for their recurrence. The purpose of this study was to evaluate the management of residual, recurrent, and metastatic intracranial hemangiopericytomas using CyberKnife (CK) stereotactic radiotherapy (SRT).Materials and MethodsData were collected from 15 patients (28 tumors; eight men and seven women; 32–58 years) with residual, recurrent, or metastatic intracranial hemangiopericytomas, who were treated with stereotactic radiotherapy using CyberKnife between January 2014 and August 2019. All patients had previously been treated with surgical resection. Initial tumor volumes ranged from 0.84 to 67.2 cm3, with a mean volume of 13.06 cm3. The mean marginal and maximum radiosurgical doses to the tumors were 21.1 and 28.76 Gy, respectively. The mean follow-up time for tumors was 34.5 months, ranging from 13 to 77 months.Results15 patients were alive after treatment; the mean post-diagnosis survival at censoring was 45.6 months (range 13–77 months). The volumes of the 28 tumors in the 15 followed patients were calculated after treatment. Postoperative magnetic resonance imaging revealed a mean tumor volume of 6.72 cm3 and a range of 0–67.2 cm3, with the volumes being significantly lower than pretreatment values. Follow-up imaging studies demonstrated tumor disappearance in seven (25%) of 28 tumors, reduction in 14 (50%), stability in one (3.57%), and recurrence in six (21.4%). Total tumor control was achieved in 22 (78.5%) of 28 tumors. The tumor grade and fraction time were not significantly associated with progression-free survival. Intracranial metastasis occurred in three patients, and extraneural metastasis in one patient.ConclusionsOn the basis of the current results, stereotactic radiotherapy using CyberKnife is an effective and safe option for residual, recurrent, and metastatic intracranial hemangiopericytomas. Long-term close clinical and imaging follow-up is also necessary.

Clinical efficacy of cyberknife in patients with primary large hepatocellular carcinoma over 70 years old

Objective: To analyze the clinical efficacy and safety of cyberknife in the treatment of patients with primary large hepatocellular carcinoma over 70 years old. Methods: A total of 82 patients (58 males and 24 females) with large hepatocellular carcinoma aged over 70 years (70 to 85 years, (75±4) years) with a median tumor diameter of 6.7 cm (5.0~10.0 cm) were retrospectively collected. All patients were diagnosed by pathology or radiography in the Cancer Radiotherapy Center of the Fifth Medical Center of the PLA General Hospital from March 2014 to December 2018, and treated with cyberknife stereotactic radiotherapy. Progression free survival rate (PFS), local control rate (LC), overall survival rate (OS) and adverse reactions were observed at 1, 2 and 3 years. Kaplan-Meier was used for survival analysis, and Cox regression model was used to analyze survival-related factors. Results: All 82 patients successfully completed radiation therapy with a median survival time of 20 months, a median PFS of 10 months, an objective response rate of 64.63% (53/82), and a disease control rate of 85.37% (70/82). After treatment, the PFS at 1, 2, and 3 years were 39.0% (32/82), 22.1% (18/82), and 17.1% (14/82), respectively; the LC at 1, 2, and 3 years were 95.1% (78/82), 92.3% (76/82), and 92.3% (76/82), respectively; and the OS at 1, 2, and 3 years were 68.3% (56/82), 48.8% (40/82) and 31.7% (26/82), respectively. Nine patients suffered from radiation-induced liver disease (RILD), and there were no deaths due to RILD. Cox regression analysis showed that alpha-fetoprotein (AFP) was an independent risk factor for OS (HR=2.304, 95%CI 1.118-4.747;P<0.05). Conclusion: Cyberknife treatment for patients with primary large hepatocellular cancer over 70 years old has higher LC and OS, better curative effect, and less treatment-related adverse reactions.

Local Tumor Control for Metastatic Epidural Spinal Cord Compression Following Separation Surgery with Adjuvant CyberKnife Stereotactic Radiotherapy or Image-Guided Intensity-Modulated Radiotherapy

We sought to compare local tumor control after conventionally fractionated image-guided intensity-modulated radiotherapy (IMRT) versus adjuvant CyberKnife stereotactic body radiotherapy (SBRT) in patients who underwent separation surgery for metastatic epidural spinal cord compression (MESCC). We retrospectively reviewed patients with MESCC who were treated at our hospital. The Kaplan-Meier method was used to estimate local progression and overall survival. Fifty-six patients with MESCC underwent separation surgery between 2013 and 2018, among whom 6 were lost to follow-up, 24 received conventionally fractionated image-guided IMRT, and 26 were treated with CyberKnife SBRT. The median follow-up was 16.5 months (range, 2.1-47.5 months). Eleven patients experienced local failure including 9 and 2 from the IMRT and SBRT groups, respectively. The local progression-free survival rates were significantly higher in the SBRT group than IMRT group at 6 months (95.5% vs. 82.0%), 1 year (90.9% vs. 71.8%), and 2 years (90.9% vs. 57.6%) (P = 0.035). Multivariate Cox proportional hazards regression analysis identified radiotherapy method (P = 0.034) and receipt of preoperative radiotherapy (P = 0.047) as significant predictors of local control, while visceral metastasis (P = 0.048) and high-malignancy primary tumor type (P = 0.002) were negative predictors of overall survival. Moreover, postoperative SBRT was noninferior to IMRT in terms of pain control, adverse effects, and performance in treating irradiated spinal metastases. Hybrid surgery-radiosurgery therapy is a safe and effective treatment option for patients with MESCC. SBRT provided higher local control rates compared with IMRT. Thus postoperative SBRT should be considered for patients expected to have relatively long survival.

Efficacy of frameless stereotactic radiotherapy for the treatment of presumptive canine intracranial gliomas: A retrospective analysis (2014-2017).

The use of conventional multi-fractionated radiotherapy for the treatment of glial tumours is well documented in the literature. Recently, stereotactic radiotherapy (SRT) has become more widely available allowing for hypo-fractionated protocols; however, its usefulness in the treatment of canine intracranial gliomas is largely undetermined. We conducted a retrospective analysis, including 21 dogs diagnosed with presumptive intracranial gliomas treated with one or more courses of three fractions of 8 to 10 Gy CyberKnife SRT. The objective of this study was to evaluate the efficacy, safety and prognostic factors associated with the use of SRT for the treatment of canine intracranial gliomas. Overall MST for all dogs was 636 days (d). Dogs treated with one course of the described SRT protocol had a MST of 258 days while those treated with >1 course had a MST of 865 days (P = .0077 log rank, 0.0139 Wilcoxon). Dogs treated with one course of SRT who received adjuvant chemotherapy had a MST of >658 days and lived significantly longer than those who did not receive chemotherapy (MST, 230 days) (P = .0414 log rank, 0.0453 Wilcoxon). The most common adverse event included presumptive transient demyelination in 3/21 dogs, which was treated successfully with corticosteroids in all patients. This study provides evidence that SRT is effective in prolonging survival in dogs with intracranial gliomas, and may provide similar results to conventional fractionated protocols, while decreasing the number of hospital visits and anaesthetic episodes. Additionally, it appears that patients can be safely treated with multiple rounds of SRT resulting in improved survival times.

The Retrospective Evaluation of The Local Tumor Control and Adverse Effects of Treatment in Patients Treated Using Cyberknife Stereotactic Radiotherapy in Vestibular Schwannomas

The Retrospective Evaluation of The Local Tumor Control and Adverse Effects of Treatment in Patients Treated Using Cyberknife Stereotactic Radiotherapy in Vestibular Schwannomas

Improving stereotactic radiotherapy (SRT) planning process for brain metastases by Cyberknife system: reducing dose distribution in healthy tissues.

Purpose: To pursue high precision dose in lesions and steeper dose fall-off in healthy tissues of brain metastases stereotactic radiotherapy (SRT), this study investigated an opitimized planning by comparison different prescription dose line in the treatment of brain metastases using Cyberknife (CK) Robotic Radiosurgery System.Methods: 77 patients (92 lesions) brain metastases patients CK SRT plans were replanned with 50%-80% (5% internal) prescription dose line to cover more than 95% of the planned target volume (PTV), under the same collimator by Multiplan System. Under the precondition of guaranteeing plans all meet the clinical requirements, the plan evaluation paraments (conformal index (CI) and homogeneity index (HI)), plan treatment time parameters (the total number of beams and monitor units (MU)) and dose distribution of organs at risk (OAR) and healthy brain tissues adjacent to the PTV were analyzed respectively.Resluts: Compared with 70% plans, 65% plans had: 1) average dose (Dmean) and maximum dose (Dmax) of healthy brain tissue outside of the PTV reduced 11.83% and 5.97% markedly; 2) Dmean and Dmax of brainstem decreased 11.43% and 2.86%; 3) the volumes of whole brain minus the tumors received a single dose equivalence of 12 Gy/14 Gy (V12Gy/V14Gy) had marked decline. The dose fall-off was considerably faster in the 60%-65% plans around the PTV and the maximum dose of healthy tissue was prominently lower. While the difference in CI and HI between different plans was not obvious, the plan treatment time was a little higher in 60%-65% plans than 70%-80% plans.Conclusions: Choosing a relatively lower isodose as the prescription dose line for brain metastases CK SRT planing could improve the dosimetry index of target and immensely reduce high dose in healthy brain tissue and OAR.

Fractionated CyberKnife Stereotactic Radiotherapy for Perioptic Pituitary Adenomas

Stereotactic radiosurgery (SRS) is the reference standard for radiotherapy for pituitary adenomas but has been limited to lesions with sufficient distance (i.e., >3 mm) from the optic apparatus. We used marginless, fractionated (i.e., 25-28 fractions) stereotactic radiotherapy and the CyberKnife to treat pituitary adenomas that were not eligible for SRS. We present the clinical outcomes, including local control, endocrine function, and toxicity from modern fractionated radiotherapy. A total of 53 patients were treated for pituitary adenomas within 3 mm of the optic apparatus. The primary endpoint was tumor control with the secondary endpoints of vision and pituitary function preservation and endocrine control in hormone-secreting tumors. The tumor control rate as measured on magnetic resonance imaging as either stable or decreased in size was 98.1% (52 of 53) at a mean follow-up of 32.5 months (range, 3-77). All patients experienced preservation or improvement of their preexisting vision status. No change in pituitary function was noted in 52 of the 53 patients (98.1%). One patient experienced worsening of pituitary function secondary to pituitary apoplexy that occurred 4 months after treatment. The endocrine control rate in hormone-secreting tumors was 75% (6 of 8). Marginless, fractionated CyberKnife radiotherapy demonstrated excellent local tumor control and endocrine control rates, comparable to those with SRS, with preservation of vision in patients with adenomas in close proximity to the optic pathway.

Effects of CyberKnife therapy for vestibular schwannoma on hearing: a retrospective study.

To evaluate the effects of CyberKnife stereotactic radiotherapy for the treatment of vestibular schwannoma on hearing, as evaluated by audiological tests. Patients with vestibular schwannoma were evaluated before and after CyberKnife radiosurgery. Evaluation included pure tone thresholds, speech discrimination scores, auditory brainstem responses and radiological signs. The study comprised 26 patients diagnosed with vestibular schwannoma and subsequently treated with CyberKnife radiosurgery. The mean follow-up time was 16.4 months. The mean post-treatment hearing preservation rate was 69.23 per cent. There was no significant relationship between hearing loss after treatment and patient age, radiation dosage during treatment, or size of tumour. With regard to auditory brainstem responses, patients with hearing loss following treatment had a significantly higher inter-peak latency between waves I-III than patients with preserved hearing. Stereotactic CyberKnife radiosurgery is an excellent alternative treatment modality for patients with vestibular schwannoma, and results in acceptable preservation of hearing. Residual hearing following CyberKnife therapy is not significantly affected by factors such as age, size of tumour or dosage of treatment.

Stereotactic radiotherapy in three weekly fractions for the management of vestibular schwannomas

PurposeThis study evaluates the rates of tumor control, hearing preservation and cranial nerve toxicity with the use of CyberKnife stereotactic radiotherapy consisting of 2100 cGy to the 80% isodose line delivered in three weekly fractions to treat vestibular schwannomas. Materials and methodsRetrospective chart review of vestibular schwannoma patients treated with CyberKnife stereotactic radiotherapy or undergoing watchful waiting between 2006 and 2017 was performed. For inclusion, patients receiving CyberKnife stereotactic radiotherapy must have had pretreatment magnetic resonance imaging and audiography, and 2 follow-up magnetic resonance imaging and audiograms. Watchful waiting patients must have had a minimum of 2 magnetic resonance imaging and 2 audiograms. ResultsForty patients met inclusion criteria. Twenty-two underwent CyberKnife stereotactic radiotherapy. Eighteen remain in watchful waiting. Crude tumor control was 86.4% at mean radiographic follow-up of 52.3 months. Kaplan-Meier progression-free survival was 76.9% at 5 years. Kaplan-Meier survival from radiographic growth was 61.5% at 5 years. Kaplan-Meier hearing preservation was 17.5% at 5 years. All patients undergoing watchful waiting presenting with serviceable hearing maintained serviceable hearing. Serviceable hearing among CyberKnife stereotactic radiotherapy patients was 42.9% prior to treatment and 14.2% through mean follow-up of 53.7 months. One patient experienced trigeminal nerve toxicity 45 months after SRT. 95.5% of CyberKnife stereotactic radiotherapy patients were complication-free. ConclusionsOur fractionation regimen provides tumor control consistent with current literature. Hearing outcomes, however, should be discussed with patients prior to CyberKnife stereotactic radiotherapy.

Predictive Model of Difference Between Conventional and Monte Carlo Algorithms for Stereotactic Body Radiation Therapy of Lung Cancer

To compare the conventional Ray Tracing (RT) and Monte Carlo (MC) dose calculations in patients treated with CyberKnife stereotactic ablative radiotherapy and find predictive model of RT/MC calculation difference prior to MC calculation. This is a study on 75 patients treated with stereotactic body radiotherapy of lung cancer. All plans were calculated with conventional RT algorithm and recalculated with MC algorithm using 1% uncertainty. The final MC plan was prescribed to the same coverage and same dose as previous RT plan (D95%). Two inhomogeneity boundaries (encloses the lung tissue - Lung shell, and the target - Target shell) were delineated as a shell structures ± 1 mm in/outside from the lung and ± 1 mm in/outside from the PTV. Lung shell is also proportional to size of lung. Volumes and mean doses of shell structures, numbers of monitor units per fraction (MU/fr), volumes of PTV and GTV, lung mean doses, volumes of lung tissue within the planning target volumes, tumor's localizations and differences in prescribed isodose lines between RT and MC were recorded. Doses and MU/fr were derived from plans calculated with conventional algorithm (RT). Statistical methods were used to find suitable variables (statistically significant) and for multivariable regression model delination. Cross-validation analysis was used to verify the model accuracy. The final prescribed isodose line was on average 80% (range 76-83) and 69% (range 53-78) for RT and MC algorithm respectively what confirmed that dose calculated with conventional algorithm is overestimated. Using the backward selection, a regression model for difference of RT/MC prescribed isodose line was built. Four regression variables (Lung shell, MU/fr, mean doses in Lung shell and Target shell) proved to be significant with p-values < 0,01. The R squared value of the model was 79%. Dividing data in two groups (estimation group consisted of 50 observations, evaluation group consisted of 25 observations) a cross-validation analysis of the model was provided. The cross-validation mean absolute error (CV MAE) equals to 1.8 (±1 in relation to MC 1% calculation uncertainty) and mean error 0.9. No single parameter can predict the difference between conventional (RT) and MC algorithms. The statistical analysis showed four significant variables which can be used in multivariable model to predict the RT/MC difference (RT overestimation). The value of CV MAE showed that our model can highlight the degree of difference from RT results prior to MC calculation. This is our preliminary result and further investigation will follow.

Safety and Efficacy of Endovascular Fiducial Marker Insertion for CyberKnife Stereotactic Radiation Therapy Planning in Early-Stage Lung Cancer

PurposeTo evaluate the safety and efficacy of endovascular fiducial markers (EVFMs) for CyberKnife stereotactic radiation therapy (RT) of malignant lung neoplasms in patients with contraindications to percutaneous fiducial marker (PTFM) placement. Materials and MethodsBetween January 2011 and December 2013, 15 patients (7 men and 8 women) aged 59–87 years (mean, 73 y) underwent EVFM placement and 109 patients (54 men and 55 women) aged 55–92 years (mean, 73 y) underwent 114 PTFM placements. All patients who received EVFMs had contraindications to PTFM insertion. Complications were recorded for all 129 procedures. Proportions of markers used for CyberKnife stereotactic RT planning and distance between markers and tumor were assessed in all 15 patients in the EVFM group and in 15 randomly selected patients in the PTFM group. ResultsSixty-two EVFMs and 56 PTFMs were inserted in the groups of 15 patients. CyberKnife stereotactic RT was not performed in 2 EVFM recipients (8 EVFMs) and 1 PTFM recipient (4 PTFMs). CyberKnife stereotactic RT was planned with the use of 39 of 54 EVFMs (72%) in 13 patients and 37 of 52 PTFMs (71%) in 14 patients. Mean distances between the tumor and EVFMs and PTFMs were 5.5 mm and 2.7 mm, respectively (P = .0152). No complications occurred in the EVFM group. In the PTFM group, 60 of 114 patients (52.6%) had small or moderate pneumothoraxes, 13 (11.4%) had chest tubes inserted, and 5 (4.4%) had self-limiting hemoptysis. ConclusionsEVFM is feasible and safe, and may therefore offer an alternative when patients are not candidates for percutaneous marker placement.

PO-0826: Evaluation of the new InCise MLC for Cyberknife stereotactic radiotherapy

PO-0826: Evaluation of the new InCise MLC for Cyberknife stereotactic radiotherapy

First Australian experience of treating localised prostate cancer patients with CyberKnife stereotactic radiotherapy: early PSA response, acute toxicity and quality of life.

IntroductionThis study is to evaluate biochemical response, acute toxicity and health‐related quality‐of‐life (QOL) outcomes among prostate cancer patients following stereotactic body radiation therapy (SBRT) in the first Australian CyberKnife facility.MethodsForty‐five consecutive patients with clinically localised prostate cancer were treated with SBRT using CyberKnife technology and enrolled in this study. Protocol treatment consisted of 36.25 Gy in five fractions. PSA and acute toxicity was assessed at each follow‐up visit and QOL was assessed using the European Organisation for Research and Treatment of Cancer (EORTC) Global Health Status (GHS) C30 and PR25 questionnaires and the Karnofsky Performance Status (KPS). Distance of travel for treatment was recorded.ResultsThe median prostate‐specific antigen (PSA) level declined from the initial value of 6.9 ng/mL to 1.5 ng/mL at 6 months and 0.6 ng/mL at 18 months post‐treatment. Results were similar in patients who did not receive hormone therapy. Acute grade 1 gastrointestinal (GI) and genitourinary (GU) toxicities were found in 11.1% and 24.4% of patients respectively. Acute grade 2 GI and GU toxicities were found in 2.2% and 11.1% of patients respectively. There were no grade 3 and grade 4 toxicities. Mean urinary symptom score was 14.8 at baseline, 17.2 at 6 weeks and 18.3 at 6 months (P > 0.05). Mean bowel symptom score was 2.7 at baseline, 4.2 at 6 weeks and 6.3 at 6 months (P > 0.05). The mean GHS score improved from 81.3 at baseline to 82.4 at 6 weeks, and was 75.6 at 6 months (P > 0.05, not significant). Compared to baseline KPS, there was a significant mean decrease from baseline of 96.7 to 93.3 at the 6‐week follow‐up (P = 0.0043), which then recovered to 94.3 at the 6‐month follow‐up (P = 0.1387).ConclusionsEarly results show promising PSA response. Acute toxicity seemed comparable to results from conventionally fractionated radiotherapy and to international prostate SBRT studies. EORTC PR25 and C30 scores did not reveal any significant change from baseline, and although there was a decrease in KPS, the absolute decrease was small.

P076 - CyberKnife stereotactic radiotherapy for isolated recurrence in the prostatic bed

P076 - CyberKnife stereotactic radiotherapy for isolated recurrence in the prostatic bed