Lung Metastases Treated by CyberKnife® Image-Guided Robotic Stereotactic Radiosurgery at 41 Months:

AAPM task group report 135.B: Quality assurance for robotic radiosurgery

AAPM Task Group Report 135.B covers new technology components that have been added to an established radiosurgery platform and updates the components that were not well covered in the previous report. Considering the current state of the platform, this task group (TG) is a combination of a foundational task group to establish the basis for new processes/technology and an educational task group updating guidelines on the established components of the platform. Because the technology discussed in this document has a relatively small user base compared to C-arm isocentric linacs, the authors chose to emphasize the educational components to assist medical physicists who are new to the technology and have not had the opportunity to receive in-depth vendor training at the time of reading this report. The TG has developed codes of practice, introduced QA, and developed guidelines which are generally expected to become enduring practice. This report makes prescriptive recommendations as there has not been enough longitudinal experience with some of the new technical components to develop a data-based risk analysis.

Stereotactic ablative body radiotherapy with a central high dose using CyberKnife for metastatic lung tumors

BACKGROUND

The CyberKnife system features a robotically-positioned linear accelerator to deliver real-time image-guided stereotactic ablative body radiotherapy (SABR). It achieves steep dose gradients using irradiation from hundreds of different directions and increases the central dose of the gross tumor volume (GTV) without increasing the marginal dose to the planning target volume. We evaluated the effectiveness and safety of SABR with a central high dose using CyberKnife for metastatic lung tumors.

METHODS

A total of 73 patients with 112 metastatic lung tumors treated with CyberKnife were retrospectively analyzed. Local control, progression-free survival, and overall survival were calculated using the Kaplan-Meier method. The median age was 69.2 years. The most common primary sites were the uterus (n = 34), colorectum (n = 24), head and neck (n = 17), and esophagus (n = 16). For peripheral lung tumors, the median radiation dose was 52 Gy in 4 fractions, whereas for centrally located lung tumors, it was 60 Gy in 8-10 fractions. The dose prescription was defined as 99% of the solid tumor components of the GTV. The median maximum dose within the GTV was 61.0 Gy. The GTV and planning target volume were enclosed conformally by the 80% and 70% isodose lines of the maximum dose, respectively. The median follow-up period was extended to 24.7 months; it was 33.0 months for survivors.

RESULTS

The 2-year local control, progression-free survival, and overall survival rates were 89.1%, 37.1%, and 71.3%, respectively. Toxicities of grade ≥ 2 were noted as grade 2 and 3 radiation pneumonitis in one patient each. The two patients with grade 2 or higher radiation pneumonitis had both received simultaneous irradiation at two or three metastatic lung tumor sites. No toxicity of grade ≥ 2 was observed in patients with metastasis in one lung only.

CONCLUSIONS

SABR with a central high dose using CyberKnife for metastatic lung tumors is effective with acceptable toxicity.

TRIAL REGISTRATION

Number: 20557, Name: Stereotactic ablative radiotherapy using CyberKnife for metastatic lung tumor, URL: http://www.radonc.med.osaka-u.ac.jp/pdf/SBRT.pdf , Date of registration: April 1, 2021 (retrospectively registered), Date of enrollment: May 1, 2014.

Stereotactic radiotherapy for lung oligometastases

30-60% of cancer patients develop lung metastases, mostly from primary tumors in the colon-rectum, lung, head and neck area, breast and kidney. Nowadays, stereotactic radiotherapy (SRT ) is considered the ideal modality for treating pulmonary metastases. When lung metastases are suspected, complete disease staging includes a total body computed tomography (CT ) and/or positron emission tomography-computed tomography (PET -CT ) scan. PET -CT has higher specificity and sensitivity than a CT scan when investigating mediastinal lymph nodes, diagnosing a solitary lung lesion and detecting distant metastases. For treatment planning, a multi-detector planning CT scan of the entire chest is usually performed, with or without intravenous contrast media or esophageal lumen opacification, especially when central lesions have to be irradiated. Respiratory management is recommended in lung SRT, taking the breath cycle into account in planning and delivery. For contouring, co-registration and/or matching planning CT and diagnostic images (as provided by contrast enhanced CT or PET-CT ) are useful, particularly for central tumors. Doses and fractionation schedules are heterogeneous, ranging from 33 to 60 Gy in 3-6 fractions. Independently of fractionation schedule, a BED10 > 100 Gy is recommended for high local control rates. Single fraction SRT (ranges 15-30 Gy) is occasionally administered, particularly for small lesions. SRT provides tumor control rates of up to 91% at 3 years, with limited toxicities. The present overview focuses on technical and clinical aspects related to treatment planning, dose constraints, outcome and toxicity of SRT for lung metastases.

Radiation-Induced Secondary Cancer Risk Assessment in Patients With Lung Cancer After Stereotactic Body Radiotherapy Using the CyberKnife M6 System With Lung-Optimized Treatment

Background

To evaluate the lifetime secondary cancer risk (SCR) of stereotactic body radiotherapy (SBRT) using the CyberKnife (CK) M6 system with a lung-optimized treatment (LOT) module for lung cancer patients.

Methods

We retrospectively enrolled 11 lung cancer patients curatively treated with SBRT using the CK M6 robotic radiosurgery system. The planning treatment volume (PTV) and common organs at risk (OARs) for SCR analysis included the spinal cord, total lung, and healthy normal lung tissue (total lung volume - PTV). Schneider’s full model was used to calculate SCR according to the concept of organ equivalent dose (OED).

Results

CK-LOT-SBRT delivers precisely targeted radiation doses to lung cancers and achieves good PTV coverage and conformal dose distribution, thus posing limited SCR to surrounding tissues. The three OARs had similar risk equivalent dose (RED) values among four different models. However, for the PTV, differences in RED values were observed among the models. The cumulative excess absolute risk (EAR) value for the normal lung, spinal cord, and PTV was 70.47 (per 10,000 person-years). Schneider’s Lnt model seemed to overestimate the EAR/lifetime attributable risk (LAR).

Conclusion

For lung cancer patients treated with CK-LOT optimized with the Monte Carlo algorithm, the SCR might be lower. Younger patients had a greater SCR, although the dose–response relationship seemed be non-linear for the investigated organs, especially with respect to the PTV. Despite the etiological association, the SCR after CK-LOT-SBRT for carcinoma and sarcoma, is low, but not equal to zero. Further research is required to understand and to show the lung SBRT SCR comparisons and differences across different modalities with motion management strategies.

Peripheral Lung Nodule Diagnosis and Fiducial Marker Placement Using a Novel Tip-Tracked Electromagnetic Navigation Bronchoscopy System

BACKGROUND

Electromagnetic navigation (EMN) has improved bronchoscopic access to peripheral pulmonary nodules. A novel EMN system utilizing novel tip-tracked instruments for endobronchial [electromagnetic navigation bronchoscopy (ENB)] as well as transthoracic lung biopsy [electromagnetic-guided transthoracic needle aspiration (EMTTNA)] has become available. The system provides real-time feedback as well as the ability to biopsy lesions outside of the airway. These advances have the potential to improve diagnostic yield over previous EMN systems.

METHODS

We performed a retrospective review of consecutive peripheral bronchoscopy cases utilizing a novel EMN platform for biopsy and/or fiducial marker (FM) placement at a tertiary care university hospital. We analyzed factors that may influence diagnostic yield including lesion size.

RESULTS

Our study included 108 patients who underwent EMN-guided bronchoscopy between June 2015 and April 2017 for the diagnosis of peripheral lung lesions and/or the placement of FMs for stereotactic body radiotherapy. Ninety-three patients underwent biopsy utilizing ENB +/- EMTTNA. The combined diagnostic yield was 78%. EMTTNA provided a diagnosis for 5 patients in whom the ENB biopsy results were negative. Diagnostic yield by nodules <20, 20 to 30, and >30 mm in size was 30/45 (67%), 27/30 (90%), and 16/18 (89%), respectively. Sixty-five patients underwent FM placement with a total of 133 FM placed.

CONCLUSION

This novel tip-tracked EMN system incorporating both ENB and EMTTNA can guide biopsy and FM placement with a high degree of success and with a low complication rate. Multicentered prospective trials are required to develop algorithmic approaches to combine ENB and EMTTNA into a single procedure.

Convex Probe EBUS-guided Fiducial Placement for Malignant Central Lung Lesions

BACKGROUND

Stereotactic body radiotherapy (SBRT) had become a therapeutic modality in patients with primary tumors, locally recurrent as well as oligometastasis involving the lung. Some modalities of SBRT require fiducial marker (FM) for dynamic tumor tracking. Previous studies have focused on evaluating bronchoscopic-guided FM placement for peripheral lung nodules. We describe the safety and feasibility of placing FM using real-time convex probe endobronchial ultrasound (CP-EBUS) for SBRT in patients with centrally located hilar/mediastinal masses or lymph nodes.

METHODS

This is a retrospective review of patients who were referred to Beth Israel Deaconess Medical Center's multidisciplinary thoracic oncology program for FM placement to pursue SBRT.

RESULTS

Thirty-seven patients who underwent real-time CP-EBUS were included. Patients had a median age of 71 years [interquartile range (IQR), 59.5 to 80.5]. The median size of the lesion was 2.2 cm (IQR, 1.4 to 3.3 cm). The median distance from the central airway was 2.4 cm (IQR, 0 to 3.4 cm). A total of 51 FMs (median of 1 per patient) were deployed in 37 patients. At the time of SBRT planning, 46 (90.2%) were confirmed radiologically in 32 patients. Patients with unsuccessful fiducial deployment (n=5) underwent a second procedure using the same technique. Of those, 3 patients had a successful fiducial placement via bronchoscopy, 1 patient required FM placement by percutaneous computed tomography-guided approach and 1 patient required FM placement through EUS by gastroenterology.

CONCLUSION

CP-EBUS-guided FM placement for patients with malignant lymph nodes and central parenchymal lung lesions appears to be safe and feasible.

A matched-pair analysis of stereotactic body radiotherapy (SBRT) for oligometastatic lung tumors from colorectal cancer versus early stage non-small cell lung cancer

BACKGROUND

The use of stereotactic body radiotherapy (SBRT) for early-stage primary non-small cell lung cancer (NSCLC) reported excellent local control rates. But the optimal SBRT dose for oligometastatic lung tumors (OLTs) from colorectal cancer (CRC) has not yet been determined. This study aimed to evaluate whether SBRT to a dose of 48-60 Gy in 4-5 fractions could result in similar local outcomes for OLTs from CRC as compared to early-stage NSCLC, and to examine potential dose-response relationships for OLTs from CRC.

METHODS

OLTs from CRC and primary NSCLCs treated with SBRT to 48-60 Gy in 4-5 fractions at a single institution were evaluated, and a matched-pair analysis was performed. Local recurrence-free survival (LRFS) was estimated by the Kaplan-Meier method. Univariate Cox regression was performed to identify significant predictors.

RESULTS

There were 72 lung lesions in 61 patients (24 OLTs from CRC in 15 patients and 48 NSCLCs in 46 patients) were analyzed with a median follow-up of 30 months. LRFS for OLTs from CRC was significantly worse than that of NSCLC when treated with 48-60 Gy/4-5 fx (p = 0.006). The 1, 3 and 5-year LRFS of OLTs from CRC vs NSCLC were 80.6% vs. 100%, 68.6% vs. 97.2%, and 68.6% vs. 81.0%, respectively. On univariate analysis, OLTs from CRC treated with higher dose (BED₁₀ = 132 Gy) exhibited significantly better local recurrence-free survival than those treated to lower doses (BED₁₀ ≤ 105.6 Gy) (p = 0.0022). The 1 and 3-year LRFS rates for OLTs treated to a higher dose (BED₁₀ = 132 Gy) were 88.9% and 81.5%, vs 33.3%, and not achieved for lower doses (BED₁₀ ≤ 105.6 Gy).

CONCLUSION

The LRFS of OLTs from CRC after SBRT of 48-60 Gy/4-5 fx was significantly worse than that of primary NSCLC. Lower dose SBRT appeared to have inferior control for OLTs of CRC in this cohort. Further studies with larger sample sizes are needed.

Treatment for non-small-cell lung cancer and circulating tumor cells

Surgery is the main curative therapy for patients with localized non-small-cell lung cancer while radiotherapy (RT), alone or with concurrent platinum-based chemotherapy, remains the primary curative modality for locoregionally advanced non-small-cell lung cancer. The risk of distant metastasis is high after curative-intent treatment, largely attributable to the presence of undetected micrometastases, but which could also be related to treatment-related increases in circulating tumor cells (CTCs). CTC mobilization by RT or systemic therapies might either reflect efficient tumor destruction with improved prognosis, or might promote metastasis and thus represent a potential therapeutic target. RT may induce prometastatic biological alterations in CTC at the cellular level, which are detectable by 'liquid biopsies', though their rarity represents a major challenge. Improved methods of isolation and ex vivo propagation will be essential for the future of CTC research.

Stereotactic Ablative Body Radiotherapy for Lung Metastases: Where is the Evidence and What are We Doing With It?

This review provides an overview of the use of stereotactic ablative body radiotherapy (SABR) for pulmonary metastases. The local control rates after SABR are generally >90%. Whether this also translates into a significant improvement in overall survival is the subject of ongoing studies. New exciting opportunities including the integration of SABR with targeted and immune therapies as well as some competing treatment strategies are discussed.

Ablative Therapy for Oligometastatic Non-Small Cell Lung Cancer

The oligometastatic state represents a distinct entity among those with metastatic disease and consists of patients with metastases limited in number and location, representing an intermediate state between locally confined and widely metastatic cancer. Although similar, "oligorecurrence" (limited number of metachronous metastases under conditions of a controlled primary lesion) and "oligoprogressive" (disease progression at a limited number of sites with disease controlled at other disease sites) states are distinct entities. In non-small cell lung cancer (NSCLC), the oligometastatic state is relatively common, with 20% to 50% of patients having oligometastatic disease at diagnosis. This subgroup of patients when receiving ablative therapy, such as surgery or stereotactic body radiation radiotherapy, can obtain markedly long progression-free and overall survival. The role of radical treatment for intracranial oligometastases is well established. Fewer data exist regarding radical treatment of extracranial metastases in lung cancer; however, retrospective series using surgery or stereotactic body radiotherapy for extracranial oligometastatic disease in NSCLC have shown excellent local control, with a suggestion of improvement in progression-free survival. In the present report, we have reviewed the data on the treatment of brain metastases in oligometastatic NSCLC and the results of ablative treatment of extracranial sites. Recently, the first randomized trial comparing ablative treatment versus control in oligometastatic disease was reported, and those data are reviewed in the context of smaller series. Finally, areas of controversy are discussed and a therapeutic approach for patients with oligometastatic disease is proposed.

Gafchromic EBT-XD film: Dosimetry characterization in high-dose, volumetric-modulated arc therapy

Radiochromic films are important tools for assessing complex dose distributions. Gafchromic EBT-XD films have been designed for optimal performance in the 40-4,000 cGy dose range. We investigated the dosimetric characteristics of these films, including their dose-response, postexposure density growth, and dependence on scanner orientation, beam energy, and dose rate with applications to high-dose volumetric-modulated arc therapy (VMAT) verification. A 10 MV beam from a TrueBeam STx linear accelerator was used to irradiate the films with doses in the 0-4,000 cGy range. Postexposure coloration was analyzed at postirradiation times ranging from several minutes to 48 h. The films were also irradiated with 6 MV (dose rate (DR): 600 MU/min), 6 MV flattening filter-free (FFF) (DR: 1,400 MU/ min), and 10 MV FFF (DR: 2,400 MU/min) beams to determine the energy and dose-rate dependence. For clinical examinations, we compared the dose distribu-tion measured with EBT-XD films and calculated by the planning system for four VMAT cases. The red channel of the EBT-XD film exhibited a wider dynamic range than the green and blue channels. Scanner orientation yielded a variation of ~ 3% in the net optical density (OD). The difference between the film front and back scan orientations was negligible, with variation of ~ 1.3% in the net OD. The net OD increased sharply within the first 6 hrs after irradiation and gradually afterwards. No significant difference was observed for the beam energy and dose rate, with a variation of ~ 1.5% in the net OD. The gamma passing rates (at 3%, 3 mm) between the film- measured and treatment planning system (TPS)-calculated dose distributions under a high dose VMAT plan in the absolute dose mode were more than 98.9%.

Convex Endobronchial Ultrasound-Guided Fiducial Placement for Malignant Central Lung Lesions: A Case Series

BACKGROUND

Stereotactic radiotherapy is a useful therapeutic modality in patients with lung cancer and patients with pulmonary metastases who cannot tolerate, are not candidates for, or do not want surgery. Successful use of radial endobronchial ultrasound (EBUS) and navigation bronchoscopy to guide the placement of the fiducials required for stereotactic radiotherapy in peripheral lung lesions has been previously reported. We present the first series of patients in which convex-probe EBUS was used to deliver fiducials to hilar and mediastinal lymph nodes as well as central thoracic lesions.

METHODS

Retrospective case series of 5 patients in which convex-probe EBUS was used to place fiducials in central lesions.

RESULTS

Fiducial markers were successfully placed in all 5 patients and were durable. There were no procedure-related complications.

CONCLUSION

Convex-probe EBUS is a useful tool in the placement of fiducial markers in patients with malignant lymphadenopathy and central parenchymal lung lesions.

Stereotactic ablative radiotherapy for pulmonary oligometastases and oligometastatic lung cancer

An increasing body of experience suggests that oligometastasis represents a minimal metastatic state with the potential for cure or prolonged survival in selected patients treated with radical local therapy to all identified sites of disease. The main clinical scenarios managed by thoracic oncology specialists are pulmonary oligometastases from primary malignancies of other anatomic sites and primary lung cancer with oligometastases to lung or other organs. Surgery has been a mainstay of treatment in these situations, with remarkably favorable outcomes following pulmonary metastasectomy in well-selected patient cohorts. As with early stage lung cancer in patients who are medically inoperable, stereotactic ablative radiotherapy is emerging as a prominent local treatment option for oligometastatic disease. We review the role and clinical experience of stereotactic ablative radiotherapy for pulmonary oligometastases and oligometastatic lung cancer.

Clinical outcomes of cyberknife stereotactic radiosurgery for lung metastases

BACKGROUND

Cyberknife stereotactic radiosurgery is an emerging noninvasive technique for treating oligometastatic cancer. The aim of this study is to evaluate the efficacy and tolerability of cyberknife for the treatment of patients with lung metastases.

MATERIALS AND METHODS

A total of 134 lung metastases in 95 patients were treated with cyberknife in the radiotherapy center of our hospital from March 2009 to March 2013. The number of lung metastases per patient ranged from one to four (single lesions in 63 patients, 66.3%). The average tumor volume was 14.6 cm(3) and the prescribed radiation dosage ranged from 30  to 60 Gy, fractionated one to five times with a 60% to 88% isodose line. The primary end point was local control (LC); secondary end points were survival and toxicity.

RESULTS

The median follow-up was 17 months (ranging from 4 to 46 months). The 1-year LC rate was 97.6%, the 2-year LC rate was 90.6%, and the 3-year LC rate was 87.0%. The median survival time was 38.0 months and the median progression-free survival (PFS) time was 14.0 months. The 2-year PFS rate was 29.0% and the overall survival (OS) rate was 61.3%. No grade 4 or higher toxicity was encountered.

CONCLUSIONS

Cyberknife is safe and effective treatment for patients with lung metastases.

Retrospective evaluation of CTV to PTV margins using CyberKnife in patients with thoracic tumors

The objectives of this study were to estimate global uncertainty for patients with thoracic tumors treated in our center using the CyberKnife VSI after placement of fiducial markers and to compare our findings with the standard CTV to PTV margins used to date. Datasets for 16 patients (54 fractions) treated with the CyberKnife and the Synchrony Respiratory Tracking System were analyzed retrospectively based on CT planning, tracking information, and movement data generated and saved in the logs files by the system. For each patient, we analyzed all the main uncertainty sources and assigned a value. We also calculated an expanded global uncertainty to ensure a robust estimation of global uncertainty and to enable us to determine the position of 95% of the CTV points with a 95% confidence level during treatment. Based on our estimation of global uncertainty and compared with our general margin criterion (5 mm in all three directions: superior/inferior [SI], anterior/posterior [AP], and lateral [LAT]), 100% were adequately covered in the LAT direction, as were 94% and 94% in the SI and AP directions. We retrospectively analyzed the main sources of uncertainty in the CyberKnife process patient by patient. This individualized approach enabled us to estimate margins for patients with thoracic tumors treated in our unit and compare the results with our standard 5 mm margin.

PACS number: 87.55‐x

Stereotactic body radiation therapy for post-pulmonary lobectomy isolated lung metastasis of thoracic tumor: survival and side effects

BACKGROUND

Stereotactic body radiation therapy (SBRT) has emerged as an alternative treatment for patients with early stage non-small cell lung cancer (NSCLC) or metastatic pulmonary tumors. However, for isolated lung metastasis (ILM) of thoracic malignances after pulmonary lobectomy, reported outcomes of SBRT have been limited. This study evaluates the role of SBRT in the treatment of such patients.

METHODS

A retrospective search of the SBRT database was conducted in three hospitals. The parameters analyzed in the treated patients were local control, progression-free survival (PFS), overall survival (OS), and the treatment-related side-effects.

RESULTS

In total, 23 patients with single ILM after pulmonary lobectomy treated with SBRT were identified and the median follow-up time was 14 months (range: 6.0-47.0 months). Local recurrences were observed in two patients during follow-up and the 1-year local control rate was 91.3%. Median PFS and OS for the studied cohort were 10.0 months [95% confidence interval (CI) 5.1-14.9 months] and 21.0 months (95% CI 11.4-30.6 months), respectively. Acute radiation pneumonitis (RP) of grade 2 or worse was observed in five (21.7%) and three (13.0%) patients, respectively. Other treatment-related toxicities included chest wall pain in one patient (4.3%) and acute esophagitis in two patients (8.7%). By Pearson correlation analysis, the planning target volume (PTV) volume and the volume of the ipsilateral lung exposed to a minimum dose of 5 Gy (IpV5) were significantly related to the acute RP of grade 2 or worse in present study (p < 0.05). The optimal thresholds of the PTV and IpV5 to predict RP of acute grade 2 or worse RP were 59 cm3 and 51% respectively, according to the receiver-operating characteristics curve analysis, with sensitivity/specificity of 75.0%/80.0% and 62.5%/80.0%.

CONCLUSIONS

SBRT for post-lobectomy ILM was effective and well tolerated. The major reason for disease progression was distant failure but not local recurrence. The PTV and IpV5 are potential predictors of acute RP of grade 2 or higher and should be considered in treatment planning for such patients.

Image-guided robotic stereotactic radiotherapy for synchronous cancer of maxillary gingiva and lung

The use of stereotactic body radiation therapy is rapidly increasing among patients with lung cancer not amenable to surgery. The authors report their experience using the CyberKnife system (Accuray Inc., Sunnyvale, CA, USA) as a treatment option for synchronous cancer of oral squamous cell carcinoma and a malignant lung tumour. An 88-year-old woman with two cancers (oral and lung masses) underwent CyberKnife treatment, with fiducial gold pins implanted using bronchoscopy. Toxicity was limited, and at the 2-year follow-up the lesions had not recurred.

Successful treatment of non-small cell lung tumor with 15 lesions by CyberKnife radiosurgery: A case report

Stereotactic body radiation therapy (SBRT) plays an important role in the treatment of early stage non-small cell lung cancer (NSCLC), particularly when patients are unable to tolerate surgical resection due to comorbid conditions or are unwilling to undergo surgery. High rates of local tumor control that may rival the results of surgery have been demonstrated in certain cases with the practical advantage of a short course of treatment and acceptable toxicity. However, there are few reports of a marked change in the complete response of high risk lung cancer with more than ten lesions. In the present study, we report a case of adenocarcinoma of the lung with 15 lesions which had metastasized to the mediastinal lymph nodes. Due to advanced age, multiple lesions and metastasis to the mediastinal lymph nodes and the hilar region of the lung, the patient was treated using CyberKnife. A marked response was noted 42 days after CyberKnife radiosurgery with complete disappearance of the tumor and metastastic lesions.

Robotic stereotactic body radiation therapy for elderly medically inoperable early-stage non-small cell lung cancer

INTRODUCTION

Stereotactic body radiation therapy (SBRT) is being increasingly applied in the treatment of non-small cell lung cancer (NSCLC) because of its high local efficacy. This study aims to examine survival outcomes in elderly patients with inoperable stage I NSCLC treated with SBRT.

METHODS

A total of 31 patients with single lesions treated with fractionated SBRT from 2008 to 2011 were retrospectively analyzed. A median prescribed dose of 48 Gy was delivered to the prescription isodose line, over a median of four treatments. The median biologically effective dose (BED) was 105.6 (range 37.50-180), and the median age was 73 (65-90 years). No patient received concurrent chemotherapy.

RESULTS

With a median follow up of 13 months (range, 4-40 months), the actuarial median overall survival (OS) and progression-free survival (PFS) were 32 months, and 19 months, respectively. The actuarial median local control (LC) time was not reached. The survival outcomes at median follow up of 13 months were 80%, 68%, and 70% for LC, PFS, and OS, respectively. Univariate analysis revealed a BED of >100 Gy was associated with improved LC rates (P = 0.02), while squamous cell histology predicted for worse LC outcome at median follow up time of 13 months (P = 0.04). Increased tumor volume was a worse prognostic indicator of both LC and OS outcomes (P < 0.05). Finally, female gender was a better prognostic factor for OS than male gender (P = 0.006). There were no prognostic indicators of PFS that reached statistical significance. No acute or subacute high-grade toxicities were documented.

CONCLUSION

SBRT is a safe, feasible, and effective treatment option for elderly patients with inoperable early stage NSCLC. BED, histology, and tumor size are predictors of local control, while tumor size and gender predict OS.

Oligometastases: the new paradigm and options for radiotherapy. A critical review

Traditional oncology distinguishes between two separate and incommensurable states in the evolution of solid malignancies: the localized disease, which is curable; and the disseminated status, which is per se palliative. Recently, a huge body of evidence suggests a fundamental change in the understanding of cancer, indicating an intermediate state in the trajectory of solid malignancies: the oligometastatic state. The following review will critically analyse existing hypotheses and facts from the basic sciences and try to contextualize it in regard to the clinical evidence available to date. Consecutively, it will try to draw possible clinical consequences for application of radiotherapy in this specific clinical scenario.

Clinical efficacy of CyberKnife combined with chemotherapy and hyperthermia for advanced non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is responsible for at least 80% of all lung tumors and has a poor prognosis, since 75% of NSCLCs are first diagnosed at an advanced stage. This study was conducted to evaluate the therapeutic efficacy of CyberKnife in combination with chemotherapy and hyperthermia for selected patients with advanced non-small cell lung cancer (NSCLC). Clinical charts, imaging and pathology reports of patients with advanced NSCLC who underwent CyberKnife therapy in our Tumor Therapy Center were retrospectively reviewed. Clinical efficacy was evaluated for local control, Karnofsky performance status scale (KPS) and toxicity analysis. A total of 119 patients with 136 target areas were evaluated. A prescribed dose of 24-51 Gy to the gross tumor volume was delivered in 3-6 fractions. The median prescription dose was 35 Gy (mean, 34.73±4.80 Gy), with an average of five fractions. Patients, who voluntarily participated in the study, were assigned to one of three groups, which were as follows: CyberKnife therapy alone, CyberKnife combined with chemotherapy and CyberKnife combined with chemotherapy and hyperthermia. The median follow-up period was 6 months and curative efficiencies were 62.16, 71.79 and 90.70%, respectively, as determined by radiographic and clinical re-examinations. Patients treated by CyberKnife combined with chemotherapy and hyperthermia achieved optimal improvement in the aspect of KPS, which was statistically different compared to the other two groups (P<0.05). In conclusion, our results indicated that CyberKnife combined with chemotherapy and hyperthermia achieved favorable short-term outcomes and may be a more viable option for patients with advanced NSCLC. However, further investigations are required to evaluate long-term outcomes.

Efficacy study of CyberKnife stereotactic radiosurgery combined with CIK cell immunotherapy for advanced refractory lung cancer

CyberKnife (CK), hypofractionated stereotactic radiosurgery, is a preferred option for the treatment of advanced refractory lung cancer which is usually inoperable. Cytokine-induced killer (CIK) cell immunotherapy has a marked radiosensitization effect which aids the elimination of residual tumor cells in distant areas. The main purpose of the present study was to evaluate the clinical efficacy of CK alone and combined with CIK cell therapy for advanced refractory lung cancer. In one year, 22 patients with advanced lung cancer underwent CK therapy at a CyberKnife Center. Of these patients, 11 received CIK cell therapy before or after the CK therapy course. The median prescribed dose in the combined CK and CIK group was 35 Gy (mean, 33.8±5.0 Gy) with a median number of fractions of 5. The median dose for patients who underwent CK alone was 35 Gy (mean, 35.2±6.0 Gy). CIK cell therapy was administered according to the condition of each patient, generally 2 continuous therapeutic sessions in 2 months. The median follow-up period was 3 months. The preliminary curative efficiency rate was 81.82% for patients who underwent CK/CIK and 72.73% for those who received CK alone, according to radiographic re-examination (P>0.05). The median improvement in the Karnofsky scores of the CK/CIK group was 20 (18±10.51) compared with 10 (8.6±11.85) for those who underwent CK alone (P<0.05). The median expression of carcinoembryonic antigen (CEA) before and after treatment was 40.81 and 12.21 ng/ml, respectively, for the CK/CIK group compared with 39.04 and 26.36 ng/ml for CK alone. The median percentage of phenotype expression of the CIK cells (CD3⁺/CD8⁺ and CD3⁺/CD56⁺) in the patients who underwent CK/CIK was recorded as 64.35% (57.08±16.94%) and 15.27% (18.80±7.00%), respectively, prior to transfusion. The preliminary results of the present study suggest that CK combined with CIK cell immunotherapy improved the short-term outcomes of patients for curative efficacy, Karnofsky scores, tumor marker levels and immune status compared with alternative CK treatments, although further studies are required.

Stereotactic ablative body radiotherapy (SABR) for primary and secondary lung tumours

Stereotactic ablative body radiotherapy (SABR) represents a technological breakthrough in radiotherapy technique, with proven benefits to patients in terms of improved tumour control and overall survival. The key components of SABR are described. The current evidence base for SABR for the treatment of primary and secondary lung tumours is appraised, and key ongoing trials are identified.

Review and uses of stereotactic body radiation therapy for oligometastases

In patients with proven distant metastases from solid tumors, it has been a notion that the condition is incurable, warranting palliative care only. The term "oligometastases" was coined to refer to isolated sites of metastasis, whereby the entire burden of disease can be recognized as a finite number of discrete lesions that can be potentially cured with local therapies. Stereotactic body radiation therapy (SBRT) is a novel treatment modality in radiation oncology that delivers a very high dose of radiation to the tumor target with high precision using single or a small number of fractions. SBRT is the result of technological advances in patient and tumor immobilization, image guidance, and treatment planning and delivery. A number of studies, both retrospective and prospective, showed promising results in terms of local tumor control and, in a limited subset of patients, of survival. This article reviews the radiobiologic, technical, and clinical aspects of SBRT for various anatomical sites.

Correlation and prediction uncertainties in the cyberknife synchrony respiratory tracking system

PURPOSE

The CyberKnife uses an online prediction model to improve radiation delivery when treating lung tumors. This study evaluates the prediction model used by the CyberKnife radiation therapy system in terms of treatment margins about the gross tumor volume (GTV).

METHODS

From the data log files produced by the CyberKnife synchrony model, the uncertainty in radiation delivery can be calculated. Modeler points indicate the tracked position of the tumor and Predictor points predict the position about 115 ms in the future. The discrepancy between Predictor points and their corresponding Modeler points was analyzed for 100 treatment model data sets from 23 de-identified lung patients. The treatment margins were determined in each anatomic direction to cover an arbitrary volume of the GTV, derived from the Modeler points, when the radiation is targeted at the Predictor points. Each treatment model had about 30 min of motion data, of which about 10 min constituted treatment time; only these 10 min were used in the analysis. The frequencies of margin sizes were analyzed and truncated Gaussian normal functions were fit to each direction's distribution. The standard deviation of each Gaussian distribution was then used to describe the necessary margin expansions in each signed dimension in order to achieve the desired coverage. In this study, 95% modeler point coverage was compared to 99% modeler coverage. Two other error sources were investigated: the correlation error and the targeting error. These were added to the prediction error to give an aggregate error for the CyberKnife during treatment of lung tumors.

RESULTS

Considering the magnitude of 2sigma from the mean of the Gaussian in each signed dimension, the margin expansions needed for 95% modeler point coverage were 1.2 mm in the lateral (LAT) direction and 1.7 mm in the anterior-posterior (AP) direction. For the superior-inferior (SI) direction, the fit was poor; but empirically, the expansions were 3.5 mm. For 99% modeler point coverage, the AP margin was 3.6 mm and the lateral margin was 2.9 mm. The SI margins for 99% modeler point coverage were highly variable. The aggregate error at 95% was 6.9 mm in the SI direction, 4.6 mm in the AP direction, and 3.5 in the lateral direction.

CONCLUSIONS

The Predictor points follow the Modeler points closely. Margins were found in each clinical direction that would provide 95% modeler point coverage for 95% of the models reviewed in this study. Similar margins were found in two clinical directions for 99% modeler point coverage in 95% of models. These results can offer guidance in the selection of CTV margins for treatment with the CyberKnife.

Individualized higher dose of 70-75 Gy using five-fraction robotic stereotactic radiotherapy for non-small-cell lung cancer: a feasibility study

OBJECTIVE

To determine whether robotic stereotactic radiotherapy of 70-75 Gy delivered in five fractions results in an improved therapeutic ratio, compared with three fractions, in the treatment of peripheral non-small-cell lung cancer (NSCLC), in which case doses of up to 85 Gy in five fractions may be feasible.

MATERIALS AND METHODS

Between December 2006 and May 2010, 20 patients (9 female, 11 male, aged 65 to 88) were treated using the CyberKnife® Robotic Radiosurgery System for NSCLC with doses ranging from 67 Gy to 75 Gy based on location, histopathological type, grade of histopathological differentiation, tumor diameter/volume, and normal tissue constraints, with the doses being delivered in five fractions over 5 to 8 days. Tumor diameters ranged from 1.5 cm to 3.4 cm (median: 2.5 cm). Patients with Stage I to IV NSCLC were treated, and the results and observations were analyzed for clinical characteristics and outcomes including toxicity. All patients, except one who had refused surgery, had co-morbid conditions that precluded a lobectomy.

RESULTS

Twenty patients were followed every three months by positron emission tomography/computed tomography (PET/CT). Mean follow-up was 23 months (range: four to 58 months). Local control was achieved in all treated tumors. Three patients expired, and three developed new regional metastases, none of which was within the planning target volume (PTV). The remainder of the patients demonstrated no evidence of recurrence or continued growth detectable by PET/CT. There was no toxicity above Grade 1.

CONCLUSIONS

It is feasible to treat peripheral NSCLC with individualized maximal tolerable doses ranging from 67 Gy to 75 Gy in five fractions chosen on the basis of location, histopathological type, grade of histopathological differentiation, tumor diameter/volume, and normal tissue constraints.

CyberKnife stereotactic ablative radiotherapy for lung tumors

Stereotactic ablative radiotherapy (SABR) has emerged as a promising treatment for early stage non-small cell lung cancer, particularly for patients unable to tolerate surgical resection. High rates of local tumor control have been demonstrated with acceptable toxicity and the practical advantage of a short course of treatment. The CyberKnife image-guided robotic radiosurgery system has unique technical characteristics that make it well suited for SABR of tumors that move with breathing, including lung tumors. We review the qualities of the CyberKnife platform for lung tumor SABR, and provide a summary of clinical data using this system specifically.

Stereotactic radiotherapy for pulmonary oligometastases: a systematic review

INTRODUCTION

Hypofractionated stereotactic body radiotherapy (SBRT) is an emerging noninvasive technique for the treatment of oligometastatic cancer. The use of small numbers of large doses, should in theory, achieve high rates of local control. The aim of this literature review is to critically assess the use of SBRT for the treatment of pulmonary metastases as judged by its effect on local control, survival, and toxicity.

METHODS

A systematic literature search was performed. Both single fraction stereotactic radiosurgery (SRS) and hypofractionated radiotherapy (SBRT) were considered individually. Thirteen institutions reported results regarding SBRT and seven institutions regarding SRS (a total of 29 publications). Outcomes, techniques, radiobiology, and the scientific rigor of the reported studies were analyzed.

RESULTS

A wide range of techniques, doses, and dose fractionation schedules were found. Three hundred thirty-four patients with 564 targets were reported in the SBRT series. The 2-year weighted local control was 77.9%. The corresponding 2-year weighted overall survival was 53.7%, with a 4% rate of grade 3 or higher radiation toxicities. One hundred fifty-four patients with 174 targets were treated in the SRS series. The 2-year weighted local control was 78.6%. The corresponding weighted 2-year overall survival was 50.3%, with 2.6% rate of grade 3 or higher toxicities.

CONCLUSION

There was insufficient evidence to recommend a consensus view for optimal tumor parameters, dose fractionation, and technical delivery of treatment. This indicates the need for further prospective studies. However, high local control rates that could potentially lead to a survival benefit justifies the consideration of stereotactic radiotherapy for patients with limited pulmonary oligometastases.

Coil spring fiducial markers placed safely using navigation bronchoscopy in inoperable patients allows accurate delivery of CyberKnife stereotactic radiosurgery

OBJECTIVES

CyberKnife stereotactic body radiosurgery is a potentially curative option for medically inoperable Stage I lung cancer. Fiducial marker placement in or near the tumor is required. Transthoracic placement using computed tomography guidance has been associated with a high risk of iatrogenic pneumothorax. Electromagnetic navigation bronchoscopy offers a safer method of placing markers; however, previous studies using linear markers have shown at least a 10% dislocation rate. We describe the use of coil-spring fiducial markers placed under moderate sedation in an outpatient bronchoscopy suite.

METHODS

A total of 52 consecutive nonoperative patients with isolated lung tumors underwent fiducial placement using electromagnetic navigation bronchoscopy. Of the 52 patients, 4 received 17 linear fiducial markers, and 49 patients with 56 tumors received 217 coil-spring fiducial markers. The procedures were considered successful if the fiducial markers had been placed in or near the tumors and had remained in place without migration, allowing radiosurgery without the need for additional fiducial markers.

RESULTS

A total of 234 fiducial markers were successfully deployed in 52 patients with 60 tumors (mean diameter 23.7 mm). Of these 60 tumors, 35 (58%) were adjacent to the pleura. At CyberKnife planning, 8 (47%) of 17 linear fiducial markers and 215 (99%) of 217 coil-spring fiducial markers (P = .0001) were still in place. Of the 4 patients with linear fiducial markers, 2 required additional fiducial placements; none of the patients with coil fiducial markers required additional procedures. Three pneumothoraces (5.8%) occurred in peripheral lesions (2 were treated with a pig-tail chest tube and 1 with observation only).

CONCLUSIONS

Deployment of coil spring fiducial markers using navigation bronchoscopy can safely be performed with the patient under moderate sedation with almost no migration and a 5.8% rate of pneumothorax.

Stereotactic body radiotherapy: a review

Stereotactic body radiotherapy (SBRT) combines the challenge of meeting the stringent dosimetric requirements of stereotactic radiosurgery with that of accounting for the physiological movement of tumour and normal tissue. Here we present an overview of the history and development of SBRT and discuss the radiobiological rationale upon which it is based. The published results of SBRT for lung, liver, pancreas, kidney, prostate and spinal lesions are reviewed and summarised. The current evidence base is appraised and important ongoing trials are identified.

Surgical management of pulmonary metastases

Metastasectomy is the only curative option for some patients with secondary pulmonary malignancy. Many studies suggest a survival benefit in selected patients if complete resection of pulmonary metastases is accomplished. There are several operative approaches that may be used, with the goal of complete resection and with minimal parenchymal loss. Evaluation for resection must include ascertainment of control of the primary tumor and assessment of the ability to achieve complete resection. Minimally invasive approaches may offer advantages in quality of life outcomes, with equivalent oncologic outcomes.

Can stereotactic fractionated radiation therapy become the standard of care for early stage non-small cell lung carcinoma

Management of early stages non-small cell lung carcinoma has traditionally been surgery with radiation selected for medically inoperable patients. Recent emergence of stereotactic body radiation therapy allows for delivery of high radiation dose to the tumor while sparing normal lungs. This reviews compares loco-regional control, survival and complications rates between these two treatment modalities. Literature search identifies studies with stereotactic body radiation therapy and surgery for early stages non-small cell lung cancer. Effectiveness and toxicity of these two modalities was assessed. Stereotactic body radiation therapy is associated with minimal morbidity and provides comparable local control and survival in patients with multiple co-morbidities factors. Stereotactic body radiation therapy may become standard of care for operable early stages non-small cell lung cancer.