Case Report: Repeated Stereotactic Radiotherapy of Recurrent Ventricular Tachycardia: Reasons, Feasibility, and Safety

Stereotactic body radiotherapy (SBRT) has been reported as an attractive option for cases of failed catheter ablation of ventricular tachycardia (VT) in structural heart disease. However, even this strategy can fail for various reasons. For the first time, this case series describes three re-do cases of SBRT which were indicated for three different reasons. The purpose in the first case was the inaccuracy of the determination of the treatment volume by indirect comparison of the electroanatomical map and CT scan. A newly developed strategy of co-registration of both images allowed precise targeting of the substrate. In this case, the second treatment volume overlapped by 60% with the first one. The second reason for the re-do of SBRT was an unusual character of the substrate–large cardiac fibroma associated with different morphologies of VT from two locations around the tumor. The planned treatment volumes did not overlap. The third reason for repeated SBRT was the large intramural substrate in the setting of advanced heart failure. The first treatment volume targeted arrhythmias originating in the basal inferoseptal region, while the second SBRT was focused on adjacent basal septum without significant overlapping. Our observations suggested that SBRT for VT could be safely repeated in case of later arrhythmia recurrences (i.e., after at least 6 weeks). No acute toxicity was observed and in two cases, no side effects were observed during 32 and 22 months, respectively. To avoid re-do SBRT due to inaccurate targeting, the precise and reproducible strategy of substrate identification and co-registration with CT image should be used.

Prostate deformation during hypofractionated radiotherapy: an analysis of implanted fiducial marker displacement

BACKGROUND

To report prostate deformation during treatment, based on an analysis of fiducial marker positional differences in a large sample.

MATERIAL AND METHODS

This study included 144 patients treated with prostate stereotactic body radiation therapy after implantation in each of 4 gold fiducial markers (FMs), which were located and numbered consistently. The center of mass of the FMs was recorded for every pair of X-ray images taken during treatment. The distance between each pair of fiducials in the live X-ray images is calculated and compared with the respective distances as determined in the CT volume. The RBE is the difference between these distances. Mean RBE and intrafraction and interfraction RBE were evaluated. The intrafraction and intefraction RBE variability were defined as the standard deviation, respectively, of all RBE during 1 treatment fraction and of the mean daily RBE over the whole treatment course.

RESULTS

We analyzed 720 treatment fractions comprising 24,453 orthogonal X-ray image acquisitions. We observed a trend to higher RBE related to FM4 (apex) during treatment. The fiducial marker in the prostate apex could not be used in 16% of observations, in which RBE was > 2.5 mm. The mean RBEavg was 0.93 ± 0.39 mm (range 0.32-1.79 mm) over the 5 fractions. The RBEavg was significantly lower for the first and second fraction compared with the others (P < .001). The interfraction variability of RBEavg was 0.26 ± 0.16 mm (range 0.04-0.74 mm). The mean intrafraction variability of all FMs was 0.45 ± 0.25 mm. The highest Pearson correlation coefficient was observed between FM2 and FM3 (middle left and right prostate) (R = 0.78; P < .001). Every combination with FM4 yielded lower coefficients (range 0.66-0.71; P < .001), indicating different deformation of the prostate apex.

CONCLUSIONS

Ideally, prostate deformation is generally small, but it is very sensitive to rectal and bladder filling. We observed RBE up to 11.3 mm. The overall correlation between FMs was affected by shifts of individual fiducials, indicating that the prostate is not a "rigid" organ. Systematic change of RBE average between subsequent fractions indicates a systematic change in prostate shape.

Radiation-Induced Changes in Ventricular Myocardium After Stereotactic Body Radiotherapy for Recurrent Ventricular Tachycardia

Stereotactic body radiotherapy (SBRT) has been suggested as a promising therapeutic alternative in cases of failed catheter ablation for recurrent ventricular tachycardias (VTs) in patients with structural heart disease. This case series is the first postmortem immunohistochemical analysis of morphologic changes in the myocardium early and late after SBRT. The present findings are in line with experimental observations on apoptosis followed by fibrosis. This may explain why the effect of SBRT on VT is not predominantly immediate. Together with observation of early recurrences after SBRT for VT, these data suggest that this strategy may have rather delayed antiarrhythmic effects.

Accuracy of electroanatomical mapping-guided cardiac radiotherapy for ventricular tachycardia: pitfalls and solutions

AIMS

To analyse and optimize the interobserver agreement for gross target volume (GTV) delineation on cardiac computed tomography (CCT) based on electroanatomical mapping (EAM) data acquired to guide radiotherapy for ventricular tachycardia (VT).

METHODS AND RESULTS

Electroanatomical mapping data were exported and merged with the segmented CCT using manual registration by two observers. A GTV was created by both observers for predefined left ventricular (LV) areas based on preselected endocardial EAM points indicating a two-dimensional (2D) surface area of interest. The influence of (interobserver) registration accuracy and availability of EAM data on the final GTV and 2D surface location within each LV area was evaluated. The median distance between the CCT and EAM after registration was 2.7 mm, 95th percentile 6.2 mm for observer #1 and 3.0 mm, 95th percentile 7.6 mm for observer #2 (P = 0.9). Created GTVs were significantly different (8 vs. 19 mL) with lowest GTV overlap (35%) for lateral wall target areas. Similarly, the highest shift between 2D surfaces was observed for the septal LV (6.4 mm). The optimal surface registration accuracy (2.6 mm) and interobserver agreement (Δ interobserver EAM surface registration 1.3 mm) was achieved if at least three cardiac chambers were mapped, including high-quality endocardial LV EAM.

CONCLUSION

Detailed EAM of at least three chambers allows for accurate co-registration of EAM data with CCT and high interobserver agreement to guide radiotherapy of VT. However, the substrate location should be taken in consideration when creating a treatment volume margin.

Chronic refractory angina pectoris treated by bilateral stereotactic radiosurgical stellate ganglion ablation: first-in-man case report

Background

Refractory angina pectoris (AP) significantly impairs quality of life in patients with chronic coronary syndrome. Several minimally invasive methods (coronary sinus reducer, cell therapy, laser or shockwave revascularization, and spinal cord stimulation) or non-invasive methods (external counterpulzation) have been studied. However, their routine clinical use has not been widely implemented. Surgical or endoscopic sympathectomy is feasible for permanently relieving angina, but is often contraindicated due to the extent of complications associated with it. Neuromodulation by anaesthetic blockade of the left-sided stellate ganglion (SG) has been shown to relieve angina for days or weeks. To provide a long-term anti-anginal effect, novel pharmacological (phenol-based) or radiofrequency ablation techniques have been individually used to permanently destroy sympathetic pathways.

Case summary

We describe a first-in-man use of stereotactic radiosurgical SG ablation using a linear accelerator (CyberKnife) in a heart failure patient after myocardial infarction with chronic refractory AP. Repeated anaesthetic SG blockade in this patient resulted in a significant, but only short-term, clinical improvement. The left, and subsequently the right, SG was ablated by targeted irradiation. During the 1-year follow-up, the patient remained without angina. We did not observe any clinically relevant early or late complications. Atrial fibrillation that developed 2 months after the second procedure was deemed to be associated with a natural progression of co-existing heart failure.

Discussion

We conclude that stereotactic radiosurgical SG ablation has the potential to become a minimally invasive and low-risk procedure to treat refractory angina patients. However, this procedure needs to be evaluated in larger patient populations.

Dose escalation in advanced floor of the mouth cancer: a pilot study using a combination of IMRT and stereotactic boost

PURPOSE

We evaluated the efficiency and toxicity of stereotactic hypofractionated boost in combination with conventionally fractionated radiotherapy in the treatment of advanced floor of the mouth cancer.

METHODS

Thirty-seven patients with advanced stage of the floor of the mouth cancer, histologically confirmed squamous cell carcinoma (p16 negative) ineligible for surgical treatment, were indicated for radiochemotherapy or hyperfractionated accelerated radiotherapy (HART). The radiotherapy protocol combined external beam radiotherapy (EBRT) and a stereotactic hypofractionated boost to the primary tumor. The dose delivered from EBRT was 70-72.5 Gy in 35/50 fractions. The hypofractionated boost followed with 10 Gy in two fractions. For the variables-tumor volume, stage and grade a multivariate analysis was performed to find the relationship between overall survival, local progression and metastasis. Toxicity was evaluated according to CTCAE scale version 4.

RESULTS

After a median follow-up of 16 months, 23 patients (62%) achieved complete remission. The median time to local progression and metastasis was 7 months. Local control (LC) at 2 and 5-years was 70% and 62%, respectively. Progression-free survival (PFS) and overall survival (OS) were 57% and 49% at 2 years and 41% and 27% at 5 years, respectively. Statistical analysis revealed that larger tumors had worse overall survival and a greater chance of metastasis. Log-Rank GTV > 44 ccm (HR = 1.96; [95% CI (0.87; 4.38)]; p = 0.11). No boost-related severe acute toxicity was observed. Late osteonecrosis was observed in 3 patients (8%).

CONCLUSION

The combination of EBRT and stereotactic hypofractionated boost is safe and seems to be an effective option for dose escalation in patients with advanced floor of the mouth tumors who are ineligible for surgical treatment and require a non-invasive approach.

Real-time measurement of ICD lead motion during stereotactic body radiotherapy of ventricular tachycardia

Background

Here we aimed to evaluate the respiratory and cardiac-induced motion of a ICD lead used as surrogate in the heart during stereotactic body radiotherapy (SBRT) of ventricular tachycardia (VT). Data provides insight regarding motion and motion variations during treatment.

Materials and methods

We analyzed the log files of surrogate motion during SBRT of ventricular tachycardia performed in 20 patients. Evaluated parameters included the ICD lead motion amplitudes; intrafraction amplitude variability; correlation error between the ICD lead and external markers; and margin expansion in the superior-inferior (SI), latero-lateral (LL), and anterior-posterior (AP) directions to cover 90% or 95% of all amplitudes.

Results

In the SI, LL, and AP directions, respectively, the mean motion amplitudes were 5.0 ± 2.6, 3.4. ± 1.9, and 3.1 ± 1.6 mm. The mean intrafraction amplitude variability was 2.6 ± 0.9, 1.9 ± 1.3, and 1.6 ± 0.8 mm in the SI, LL, and AP directions, respectively. The margins required to cover 95% of ICD lead motion amplitudes were 9.5, 6.7, and 5.5 mm in the SI, LL, and AP directions, respectively. The mean correlation error was 2.2 ± 0.9 mm.

Conclusions

Data from online tracking indicated motion irregularities and correlation errors, necessitating an increased CTV-PTV margin of 3 mm. In 35% of cases, the motion variability exceeded 3 mm in one or more directions. We recommend verifying the correlation between CTV and surrogate individually for every patient, especially for targets with posterobasal localization where we observed the highest difference between the lead and CTV motion.

Oral cavity complications in oncological and hemato-oncological patients

BACKGROUND

Oral cavity injuries are very significant complications in the treatment of oncological and hemato-oncological patients. Preventive and curative interventions and patient education reduce the risk of complications and their consequences. A working group of authors from professional groups prepared recommendations for care.

PURPOSE

A basic summary of recommended interventions to prevent and treat oral cavity injuries in daily practice, defined on the basis of expert societies guidelines, trials, literature data and proven practice and on the consensus opinions of the authors group members.

RESULTS

Preventive measures and patient education are essential in the approach to dealing with oral injuries in chemotherapy, radiotherapy, risky targeted treatment and osteonecrosis of the jaw. Local care products are an important element of care, in case of infections, their antimicrobial action is essential, in case of graft-versus-host disease or in connection with targeted oncological therapy, corticoids are used.

CONCLUSION

The recommended procedures contribute to the reduction of the development, severity and consequences of oral complications in oncological and hemato-oncological patients.

Recommendation for preventive and therapeutic skin care of patients undergoing radiotherapy

BACKGROUND

Radiation dermatitis is a very common reaction to radiotherapy, affecting approx. 95% of patients with varying intensity. It is crucial to minimize its side effects. The working group that prepared this document includes physicians, nurses, representatives of the Society for Radiation Oncology, Biology and Physics of the Czech Medical Association of J. E. Purkyn&#283;, the Supportive Treatment and Care Section of the Czech Society for Oncology of the Czech Medical Association of J. E. Purkyn&#283;, the Czech Wound Management Association, the Oncological Section of Czech Association of Nurses, and dermatologists. The document has been approved by the committees of these associations.

PURPOSE

Recommendation for preventive and therapeutic skin care of patients undergoing radiotherapy in the Czech Republic.

A case report of successful elimination of recurrent ventricular tachycardia by repeated stereotactic radiotherapy: the importance of accurate target volume delineation

Background

Stereotactic body radiotherapy (SBRT) has emerged recently as a novel therapeutic alternative for patients with ventricular tachycardias (VTs) resistant to convetional treatment. Nevertheless, many aspects related to SBRT are currently unknown.

Case summary

A 66-year-old man with ischaemic heart disease, a history of coronary artery bypass graft surgery and left ventricular dysfunction was referred for recurrent symptomatic episodes of slow VT (108 b.p.m.). The arrhythmia was resistant to antiarrhythmic drug therapy with amiodarone and repeated catheter ablation. The patient was scheduled to SBRT, however, the first session failed to suppress VT recurrences. After 20 months, the patient underwent re-do ablation procedure that revealed a newly developed scar with its core adjacent to the presumed critical part of the VT substrate. Catheter ablation again failed to eliminate VT and the second session of SBRT was scheduled. To improve targeting of the VT substrate for SBRT, we applied our recently developed original method for integration of data from the electroanatomical mapping system with computer tomography images. The second session of SBRT with precise targeting using the novel strategy led within 3 months to the successful elimination of VT.

Discussion

This case report describes a patient in whom the recurrent VT was abolished only by properly targeted SBRT. Above all, the case highlights the importance of precise identification and targeting for SBRT. Our case also documents in vivo, by electroanatomical voltage mapping, the development of SBRT-related myocardial lesion. This represents an important mechanistic proof of the concept of SBRT.

The use of a battery of examination methods for detection of cervical metastases in squamous cell carcinoma of the oral cavity

INTRODUCTION

In patients with squamous cell carcinoma of the orofacial area, the presence of cervical metastases represents a single most significant prognostic factor. This fact underlines the importance of thorough examination of the cervical lymph nodes for potential tumor involvement. To verify this, the most common investigative methods are physical examination (PE), sonography (US) and computed tomography (CT), which have also been used to assess the stage of the disease in the patients in our research.

OBJECTIVE

To evaluate the performance of individual methods (physical examination, sonography, computed tomography) and combinations.

METHOD

Patients with squamous cell carcinoma of the oral cavity, who had undergone physical, US and CT examinations at our department followed by radical neck dissection were included in this retrospective study. A total of 57 patients were included.

RESULTS

The sensitivity of PE, US and CT were 38%, 69% and 61%, respectively, however CT+US combination yielded 83% sensitivity and combination of all these methods 86% sensitivity. The number of false positives was however relatively high with specificity of the 3-way combination at 65%.

CONCLUSION

A combination of our three widely available inexpensive methods detected 86% of metastases in cervical nodes. The large number of false positives however indicates that the method should rather be used for screening in selecting patients who need additional and more expensive imaging than for diagnosing cervical metastases. Also, as 14% of cervical metastases pass undetected using our method, we would recommend an additional examination at least by US+PE several weeks to a few months after the initial examination.

Osteolytic bone lesions, hypercalcemia and paraprotein, but not a myeloma: case report and review of literature

In June 2018, 77-year-old man was referred to The Department of Haematooncology, University Hospital Ostrava, for suspicion of multiple myeloma. This was supported by laboratory findings of hypercalcemia, paraprotein IgA κ in serum and by the presence of multiple osteolytic skeletal lesions. Low number of plasma cells in bone marrow sample - cytologically (3.6 %) as well as in flow cytometry (less than 95 % clonal plasma cells out of total bone marrow plasma cells) - pointed at the direction of monoclonal gammopathy of undetermined significance (MGUS). In the course of differential diagnosis of hypercalcemia, elevated level of parathormone had been found which led to the performance of 99mTc-MIBI scintigraphy where parathyroid adenoma was discovered and later histologically verified. The final diagnosis was determined as a coincidence of MGUS and primary hyperparathyroidism. This case report also contains brief differential diagnosis of hypercalcemia and osteolytic skeletal lesions and suggestions for their diagnostic algorithms.

3256Long-term safety of stereotactic body radiotherapy for ablation of ventricular tachycardia: a multicentric study

Background

Contemporary stereotactic body radiotherapy (SBRT) enables to accurately concentrate high radiation doses to small volumes of myocardial tissue. There is a rising interest in using SBRT to modify arrhythmogenic substrate in patients with previously failed radiofrequency catheter ablation. However, data on the safety of SBRT for the treatment of VT are lacking.

Purpose

This study evaluated the long-term safety of SBRT for the treatment of VT.

Methods

SBRT was performed in patients with structural heart disease and failed catheter ablation for VT. The critical part of the VT substrate was identified by electroanatomic mapping (EAM) using a combination of voltage mapping, pace mapping, and activation mapping; and it was marked on a contrast-enhanced computer tomography study as a target for radioablation. SBRT was performed using a radiosurgery system with real-time motion tracking using the tip of the electrode of an indwelling defibrillator as a fiducial marker. A total radiation dose of 25 Gy was delivered to the ablation target in a single session during free breathing. Radiation-induced toxicity was evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0.

Results

Between 2014 and 2018, 18 patients from two electrophysiology centres underwent SBRT for recurrent, drug-resistant VT after previously failed catheter ablation (17 male, 1 female; mean age 63±9 years; 14 ischemic cardiopathy, 3 dilated cardiopathy, 1 fibroma). The mean volume of the ablation target was 34±17 ml, and the mean duration of the therapy was 78±14 minutes. No patient exhibited acute (up to 3 months) elevation of troponin, pericardial effusion, or a decrease in left ventricular ejection fraction from baseline. Four patients developed acute mild nausea, which waned after antiemetic drugs. Two patients gradually developed significant progression of mitral regurgitation after SBRT. One of the patients was treated medically (grade 3 toxicity), but the other had to undergo mitral valve replacement (grade 4 toxicity). No other cardiac or pulmonary radiation related toxicity was observed during a median follow-up of 23 months. Three patients died at 54, 43, and 18 month after SBRT. None of the deaths was related to VT recurrence or complication of SBRT.

CARTO, Radiation dose and Survival

Conclusions

This is the largest series of patients who underwent EAM-guided SBRT for VT as a bailout therapy after previously failed radiofrequency catheter ablation. Our preliminary data indicate the feasibility and safety of the procedure. To further investigate long-term safety and efficacy of SBRT for VT, we initiated a prospective multicentric study (NCT03819504).

Acknowledgement/Funding

Supported by RVO-FNOs/2014

P5690Comparison of two methods to navigate the stereotactic body radiotherapy ablation for ventricular tachycardia, the invasive electrophysiological study and substrate identification

Purpose

To compare two methods used for identifying the arrhythmogenic substrate - invasive electrophysiological study versus PET-CT scar identification. The substrate is then targeted by stereotactic body radiotherapy (SBRT) in patients with previously unsuccessful radiofrequency catheter ablation.

Methodology

Patients with ischemic cardiomyopathy, LVEF less than 40% and unsuccessful conventional treatment resulting in recurring ventricular tachycardias, were divided into two groups with different methods of obtaining arrhythmogenic substrate. In the group A, invasive electrophysiological mapping was used, while in the group B, scar identification by PET-CT was done, enhanced with non-invasive body surface ecg mapping of all inducible ventricular tachycardias. This target obtained was then attacked with SBRT. We compared the size of the planned target volume (PVT), the SBRT duration, the calculated dose for the esophagus, stomach and lung and the incidence of acute complications.

Cohort description

Patients in group A were recruited from April 2014 to December 2018, patients in group B from June to December 2018. Group A (8 patients) – mean age 66, NYHA class 2.4, LVEF 29,4%. Group B (6 patients) – mean age 71, NYHA class 2.1, LVEF 25,2%. All patients were men.

Results

There was a statistically significant difference in PTV – Group A (mean 24.1ml, SD = 3,9), Group B (mean 76.0ml, SD 14.1), p<0,001 (two-sample t-test). There was no difference in the calculated secondary radiation doses acquired by surrounding organs. The most frequent adverse event was acute anorexia, occurring in 4 patients from Group A and in 2 patients from Group B. The anorexia subsided in one week time. One patient from Group B suffered from esophageal ulcer, which developed 6 months after the therapy.

Conclusion

Using invasive electrophysiology mapping to identify arrhythmogenic substrate for SBRT yields significantly smaller volume of targeted tissue. Despite this finding, we did not find any difference neither in radiation dose delivered to the surrounding organs, nor in the radiation duration.

5209Stereotactic radioablation of ventricular tachycardia guided by direct integration of 3D electroanatomic mapping: development and validation of a new method

Background

Stereotactic body radiotherapy (SBRT) has emerged as a promising bailout therapy for recurrent ventricular tachycardia (VT) in patients with failed radiofrequency catheter ablation. However, SBRT can function only if the ablation target is precisely identified.

Purpose

We sought to develop a novel method for direct integration of electroanatomic mapping (EAM) data to an SBRT work station for radioablation of VT.

Methods

Candidates for SBRT were patients with recurrent, drug-resistant VT who underwent ≥2 previous radiofrequency catheter ablations (CARTO 3, Biosense-Webster, Diamond Barr, CA) and continued to have inducible clinical VT or clinical recurrences of VT. At the end of the last catheter ablation, the operators performed additional EAM to obtain landmarks for image registration: aorta with the ostium of the left main coronary artery or left atrium with ostia of pulmonary veins. Correct position of the catheter at the landmark was verified by intra-cardiac echocardiography. VT substrate–defined by a combination of voltage mapping, pace mapping, and detection of local abnormal ventricular activity and/or late potentials was marked by custom tags as a target for SBRT. The CARTO maps were exported and converted to 3D shells with encoded EAM properties (VTK format). On the following day, the patients underwent contrast-enhanced computer tomography (CT) of the heart. Using 3D Slicer software 4.10 (slicer.org), the EAM-derived anatomical structures with the marked ablation target were projected onto CT images by landmark registration with manual correction. The CT study with the projected contours of the EAM-detected ablation target was imported as a DICOM-RT format into a stereotactic radiotherapy planning work station (Multiplan 3.5, Accuray, Sunnyvale, CA). SBRT was performed using a contemporary radiosurgery system with real-time motion tracking of the ablation target (CyberKnife 8.5, Accuray). The prescribed (X-ray) dose was 25 Gy during a single session.

Results

The proposed work-flow was verified in four patients with structural heart disease and drug-resistant VT who had 2–3 unsuccessful radiofrequency catheter ablations (all males; age: 68–78 years; left ventricular ejection fraction: 20–25%; ischemic/non-ischemic cardiomyopathy: 2/2). Integration of EAM data with CT was achieved in all patients. None of them experienced acute radiotoxicity after SBRT. At a follow-up checkup at one month, three of the patients remained arrhythmia-free. One patient experienced VT recurrence one day after SBRT, but no VTs recurred during the following month of follow-up.

Figure 1

Conclusions

This is the first report demonstrating the feasibility of SBRT of VT guided by direct integration of EAM. The proposed method is best suited as a bailout procedure for patients with previously failed catheter ablation.

Acknowledgement/Funding

M.S. was supported by ESC Research Fellowship 2018

Evaluation of spine structure stability at different locations during SBRT

BACKGROUND AND AIMS

Modern stereotactic body radiotherapy (SBRT) techniques and systems that use online image guidance offer frameless radiotherapy of spinal tumors and the ability to control intrafraction motion during treatment. These systems allow precise alignment of the patient during the entire treatment session and react immediately to random changes in this alignment. Online tracking data provide information about intrafractional changes, and this information can be useful for designing treatment strategies even if online tracking is not being used. The present study evaluated spine motion during SBRT treatment to assess the risk of verifying patient alignment only prior to starting treatment.

METHODS

This study included 123 patients treated with spine SBRT. We analyzed different locations within the spine using system log files generated during treatment, which contain information about differences in the pretreatment reference spine positions by CT versus positions during SBRT treatment. The mean spine motion and intra/interfraction motion was evaluated. We defined and assessed the spine stability and spine significant shifts (SSHs) during treatment.

RESULTS

We analyzed 462 fractions. For the cervical (C) spine, the greatest shifts were in the anterior-posterior (AP) direction (2.48 mm) and in pitch rotation (1.75 deg). The thoracic (Th) spine showed the biggest shift in the AP direction (3.68 mm) and in roll rotation (1.66 deg). For the lumbar-sacral (LS) spine, the biggest shift was found for left-right (LR) translation (3.81 mm) and roll rotation (3.67 deg). No C spine case exceeded 1 mm/1 deg for interfraction variability, but 7 of 54 Th spine cases exceeded 1 mm interfraction variability for translations (maximum value, 2.5 mm in the AP direction). The interfraction variability for translations exceeded 1 mm in 2 of 24 LS spine cases (maximum value, 1.7 mm in the LR direction). Only 13% of cases had no SSHs. The mean times to SSH were 6.5±3.9 min, 8.1±5.9 min, and 8.8±7.1 min for the C, Th, and LS spine, respectively, and the mean recorded SSH values were 1.6±0.66, 1.43±0.33, and 1.46±0.47 mm/deg, respectively.

CONCLUSION

Positional tracking during spine SBRT treatments revealed low mean translational and rotational shifts. Patient immobilization did not improve spine shifts compared with our results for the Th and LS spine without immobilization. For the most precise spine SBRT, we recommend checking the patient's position during treatment.

Stereotactic radiosurgery for ablation of ventricular tachycardia

Aims

Stereotactic body radiotherapy (SBRT) for ventricular tachycardias (VTs) could be an option after failed catheter ablation. In this study, we analysed the long-term efficacy and toxicity of SBRT applied as a bail-out procedure.

Methods and results

Patients with structural heart disease and unsuccessful catheter ablations for VTs underwent SBRT. The planning target volume (PTV) was accurately delineated using exported 3D electroanatomical maps with the delineated critical part of re-entry circuits. This was defined by detailed electroanatomic mapping and by pacing manoeuvres during the procedure. Using the implantable cardioverter-defibrillator lead as a surrogate contrast marker for respiratory movement compensation, 25 Gy was delivered to the PTV using CyberKnife. We evaluated occurrences of sustained VT, electrical storm, antitachycardia pacing, and shock; time to death; and radiation-induced events. From 2014 until March 2017, 10 patients underwent radiosurgical ablation (mean PTV, 22.15 mL; treatment duration, 68 min). After radiosurgery, four patients experienced nausea and one patient presented gradual progression of mitral regurgitation. During the follow-up (median 28 months), VT burden was reduced by 87.5% compared with baseline (P = 0.012) and three patients suffered non-arrhythmic deaths. After the blanking period, VT recurred in eight of 10 patients. The mean time to first antitachycardia pacing and shock were 6.5 and 21 months, respectively.

Conclusion

Stereotactic body radiotherapy appears to show long-term safety and effectiveness for VT ablation in structural heart disease inaccessible to catheter ablation. We report one possible radiation-related toxicity and promising overall survival, warranting evaluation in a prospective multicentre clinical trial.

Comparison of surgical intervention to Cyberknife® radiotherapy in the treatment of liver malignancies

INTRODUCTION

Surgical resection is the method of choice in treating liver malignancies. In patients who are not suitable for radical surgical treatment, the radiotherapeutic system Cyberknife® is a viable treatment option. The aim of this study is to compare short- and long-term results of both treatment methods.

METHODS

A retrospective analysis of prospectively collected data was performed, focused on patients undergoing treatment of liver malignancies either by surgical resection or by the Cyberknife® system from 2013 to 2016. Only patients treated using a single treatment method were included in the study.

RESULTS

A total of 260 patients were analysed; 142 were treated by performing surgical resection and the remaining 118 using Cyberknife® radiotherapy. Median survival was 30.65 months for the surgical resection and 22.93 for the Cyberknife® therapy; median overall survival was 27.63 months. Three-year cumulative survival was 47.4% for the resection and 19.9% for radiotherapy. Kaplan-Meier analysis did not demonstrate a statistically significant difference in disease-specific survival between both groups (p=0.082, CI 95%). Results limited only to colorectal liver metastases showed a statistically significant difference in disease-specific survival (p=0.031, CI 95%).

CONCLUSIONS

Results of this study show statistically indifferent overall disease-specific survival of both groups. However, the significant difference in 3-year survival still indicates a predominant position of surgery in the diagnostic and therapeutic management of patients with liver malignancies. Nevertheless, Cyberknife® radiotherapy may actually represent a viable treatment alternative, particularly in patients unable to undergo surgical resection, although a longer follow-up period is necessary to obtain more robust results.

[Intensity Modulated Hyperfractionated Accelerated Radiotherapy to Treat Advanced Head and Neck Cancer - Predictive Factors of Overall Survival]

AIM

The aim of this study was to evaluate overall survival (OS) and prognostic factors in patients ineligible for chemotherapy who were treated with a hyperfractionated accelerated schedule with simultaneous integrated boost.

MATERIAL AND METHODS

From May, 2008, to April, 2013, 122 patients with locally advanced nonmetastatic squamous laryngeal (14%), hypopharyngeal (30%), oropharyngeal (30%), and oral cavity (27%) cancer were treated at our institution. The median age, Karnofsky Performance Status (KPS), and gross tumor volume (GTV) of the patients were 63 years (range, 46-87 years), 80% (range, 50-100%), and 46 ml (range, 5-250 ml), resp. The median total dose of radiotherapy was 72.6 Gy (range, 62-77 Gy) at 1.4-1.5 Gy per fraction, and 55 Gy at 1.1 Gy per fraction was delivered for GTV (primary and lymphadenopathy) with a margin of 0.7 cm and regional lymphatic areas with a margin of 0.3 cm. The dose was delivered 2× a day, with a 6-8 hour interval between doses, via a 6 MeV linear accelerator. OS was estimated using the Kaplan-Meier method, and predictors of OS were analyzed using Cox proportional hazards regression.

RESULTS

The median duration of the radiotherapy series was 37 days (range, 32-45 days). The incidence of grade 3 acute toxicity was 62% for mucosa (oral cavity and/or pharynx) and 0% for skin. Confluent mucositis cleared in all cases within 21 days. No grade 4 or 5 toxicities were recorded. PEG was introduced before treatment in 55 patients (45%). The 1-and 2-year OS was 65% and 32%, resp. KPS less than 80% (RR 2.4, 95% CI 1.3-4.2; p = 0.004), cancers other than oropharyngeal or laryngeal cancer (RR 2.0, 95% CI 1.1-3.5; p = 0.016), and capacity of high GTV (RR 1.006, 95% CI 1.001-1.011; p = 0.017) were found to be negative prognostic factors for OS.

CONCLUSION

More than 30% of patients with poor prognosis survived for longer than 2 years. KPS before treatment was the strongest prognostic factor for better OS.Key words: head and neck cancer - radiotherapy dose fractionation - survival analysis - acceleration - hyperfractionation This work was supported by RVO-FNOs/2016 (HPV status as predictive and prognostic factor for primary and secondary head and neck cancer). The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 9. 3. 2017Accepted: 19. 4. 2017.

[Stereotactic Body Radiotherapy of Prostate Cancer - Effectiveness and Toxicity]

BACKGROUND

Prostate cancer is the most prevalent cancer in males and its incidence is steadily increasing. Most cases of prostate cancer are diagnosed during the early asymptomatic period, in which case the prognosis is very good. Therapies differ widely in their efficacies and toxicities, and this is an important consideration when it comes to deciding which treatment is optimal for a particular patient. One treatment method for early stage prostate cancer is stereotactic body radiotherapy (SBRT). We present the first results obtained using this modality at our institution.

PATIENTS AND METHODS

A total of 261 patients with low or intermediate risk prostate cancer were treated with SBRT between August 2010 and July 2012. Patients received a total dose of 36.25 Gy in five fractions of 7.25 Gy every other day. The toxicity of the treatment was evaluated according to RTOG criteria. For assessment of quality of life, patients filled out a modified EPIC questionnaire (Expanded Prostate Composite index).

RESULTS

Overall survival (OS) in this study was 93.1%. Biochemical relapse free survival (bRFS) was 97.7%. As expected, OS and bRFS were worse in the group of patients with an intermediate risk of recurrence. Acute and chronic urinary and gastrointestinal RTOG toxicity was very low. Quality of life after treatment, as determined using the EPIC questionnaire, was slightly reduced immediately after treatment but returned to baseline or even improved during long term follow-up.

CONCLUSION

SBRT is an effective therapeutic modality for early prostate cancer and has acceptable rates of acute and low late toxicity.Key words: prostate cancer - stereotactic body radiotherapy - quality of life The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 5. 1. 2017Accepted: 1. 2. 2017.