Efficacy evaluation of retrospectively applying the Varian normal breathing predictive filter for volume definition and artifact reduction in 4D CT lung patients.

Phase-based sorting of four-dimensional computed tomography (4D CT) datasets is prone to image artifacts due to patient's breathing irregularities that occur during the image acquisition. The purpose of this study is to investigate the effect of the Varian normal breathing predictive filter (NBPF) as a retrospective phase-sorting parameter in 4D CT. Ten 4D CT lung cancer datasets were obtained. The volumes of all tumors present, as well as the total lung volume, were calculated on the maximum intensity projection (MIP) images as well as each individual phase image. The NBPF was varied retrospectively within the available range, and changes in volume and image quality were recorded. The patients' breathing trace was analysed and the magnitude and location of any breathing irregularities were correlated to the behavior of the NBPF. The NBPF was found to have a considerable effect on the quality of the images in MIP and single-phase datasets. When used appropriately, the NBPF is shown to have the ability to account for and correct image artifacts. However, when turned off (0%) or set above a critical level (approximately 40%), it resulted in erroneous volume reconstructions with variations in tumor volume up to 26.6%. Those phases associated with peak inspiration were found to be more susceptible to changes in the NBPF. The NBPF settings selected prior to exporting the breathing trace for patients evaluated using 4D CT directly affect the accuracy of the targeting and volume estimation of lung tumors. Recommendations are made to address potential errors in patient anatomy introduced by breathing irregularities, specifically deep breath or cough irregularities, by implementing the proper settings and use of this tool.

Technical challenges of linac-based stereotactic ablative body radiotherapy: short review for non-radiation oncologists.

Stereotactic ablative radiotherapy (SABR) is a radiation technique delivering high doses of radiation in a small number of treatments, to extracranial targets. It is standard of care in patients with inoperable early stage non-small cell lung cancer, and it is increasingly used in patients with oligometastatic disease. The main advantage of SABR is a steep dose gradient, allowing delivery of high biologically effective doses to the target, while minimizing irradiation exposure of the neighboring normal tissues. This results in high rates of local control of the treated target and minimal toxicity risks, and minimal impact on the quality of life of the patients. However, it requires high precision, accuracy and reproducibility during the entire process, from simulation to treatment planning and treatment delivery. This article will focus on general principles of SABR treatment planning and delivery, with emphasis on the strategies to reduce errors related to immobilization, respiratory management and treatment verification.

Treatment of multiple intracranial metastases in radiation oncology: a contemporary review of available technologies.

The use of stereotactic radiosurgery to treat multiple intracranial metastases, frequently concurrently, has become increasingly common. The ability to accurately and safely deliver stereotactic radiosurgery treatment to multiple intracranial metastases (MIM) relies heavily on the technology available for targeting, planning, and delivering the dose. A number of platforms are currently marketed for such applications, each with intrinsic capabilities and limitations. These can be broadly categorised as cobalt-based, linac-based, and robotic. This review describes the most common representative technologies for each type along with their advantages and current limitations as they pertain to the treatment of multiple intracranial metastases. Each technology was used to plan five clinical cases selected to represent the clinical breadth of multiple metastases cases. The reviewers discuss the different strengths and limitations attributed to each technology in the case of MIM as well as the impact of disease-specific characteristics (such as total number of intracranial metastases, their size and relative proximity) on plan and treatment quality.

Linac-Based Radiosurgery for Patients With Brain Oligometastases From a Breast Primary, in the Trastuzumab Era-Impact of Tumor Phenotype and Prescribed SRS Dose.

Background: The role of stereotactic radiosurgery (SRS) in the treatment of limited numbers of brain metastases in selected breast cancer patients is well-established. Aims: To analyse outcome from a single institutional experience with SRS, to identify any significant prognostic factors and to assess the influence of Her-2, estrogen receptor status, and prescribed dose on outcome. Methods: The medical records of 56 patients treated at in a single institution between 2009 and 2014 were reviewed. Demographic, treatment related and outcome data were analyzed to identify prognostic factors in this patient population. The primary endpoints were overall survival and local control. Secondary endpoint was distant intra-cranial progression-free survival. Results: The median follow- up time for the entire cohort was 10.33 months (1.25-97.28). The overall median survival was 12.5months (95%CI = 5.8-19.2), with 53.3%, and 35.8% surviving at 1- and 2- years post-SRS. After adjustment for the effect of Her 2 status, uncontrolled extra-cranial disease at the time of SRS predicted for shorter survival (HR for death = 3.1, 95% CI = 1.4-6.9, p = 0.006). At the time of death, 75% of the patients had active, uncontrolled intra-cranial disease, with 56% these patients presenting intra-cranial disease only. Sustained local control was observed in 56 (59.6%) of 94 treated metastases. In univariate analysis, Her2 status, ERHer2 group status?, and prescribed SRS dose were highly significant for local progression free-survival (LPFS). After adjustment for the effect of Her 2 status, patients receiving 12-16 Gy can expect shorter LPFS than those receiving 18-20 Gy (HR = 1.7, 95% CI = 1.0-2.8, p = 0.043). After adjustment for the effect of dose group, patients with Her 2 negative cancer can expect shorter LPFS than those with Her 2 positive cancer (HR = 2.6, 95% CI = 1.5-4.4, p < 0.0005). Use of prior WBRT did not impact survival, local or distant intra-cranial progression-free survival. Conclusions: Survival outcome is similar to the published literature. Improved outcomes are observed in patients with Her 2-positive, controlled extracranial disease at the time of SRS and higher SRS dose delivered. Achieving intra-cranial control appears to be an important factor for the survival of the breast cancer patients in the era of targeted therapies.

Treatment completion, treatment compliance and outcomes of old and very old patients treated by dose adapted stereotactic ablative radiotherapy (SABR) for T1-T3N0M0 non-small cell lung cancer.

AIM: This is a retrospective single-institution review of the treatment completion and clinical outcomes of patients aged 75 and older, treated with stereotactic ablative body radiotherapy (SABR) for T1-T3 N0 M0 non-small cell lung cancer (NSCLC). METHODS: From April 2008 to September 2015, 200 patients, aged 75-93, received respiratory-managed, intensity-modulated-based SABR. Dose fractionation was risk-adapted and delivered in 2-3 weekly treatments. Treatment completion, local control, overall survival and treatment-related toxicities were evaluated. RESULTS: All patients completed the prescribed SABR course. However, 29 patients required interruption of at least one fraction of SABR and optimization of pain control before continuation of the fraction. Median follow-up was 20.9 months. The median OS was 31.6 months with 1-,3-year survival rates of 80.7%, and 44.4% respectively. Local control at 1- and 3- years were 97.6%, 83.5% respectively. Treatment was well-tolerated. However, there were two (1%) G5 (fatal) toxicities: one acute sudden dyspnoea of unknown cause and one late SABR-related haemoptysis. No statistically significant differences in outcomes/toxicities were observed between old (75-84 years old) and very old patients (>85 years old). CONCLUSIONS: Old and very old patients can successfully complete SABR for NSCLC, with good local control, survival and acceptable toxicity. Old patients might require increased supportive care for successful treatment delivery.

Patients with colorectal lung oligometastases (L-OMD) treated by dose adapted SABR at diagnosis of oligometastatic disease have better outcomes than patients previously treated for their metastatic disease.

AIM: To evaluate the clinical outcomes of patients with OMD from a CRC primary, who underwent SABR either as first treatment at diagnosis of metachronous oligometastatic disease to lung or at progression in lung after prior treatments for metastatic disease. METHODS: This is a retrospective review of 60 patients with 85 lung oligometastases treated by SABR at two institutions, between May 2009 and September 2014. Local control (LC), overall survival (OS), progression - free survival (PFS), and toxicity were evaluated. RESULTS: Median follow-up was 22.9±15.5 months (range: 2.6-68.6). For the entire cohort, LC was observed for 76.6% of the target lesions; the 2- year OS and PFS were 77% and 28 % respectively. After a median of 7.9 months from SABR, 39 patients presented a first progression. In univariate analysis, patients with multiple recurrences prior to SABR (p=0.001) and those who received chemotherapy for metastatic progression (p=0.014) had poorer PFS from time of SABR. Median PFS for patients with no prior treatment for L-OMD vs. prior chemotherapy +/- local treatment vs. local treatment only was: not reached vs. 8.83 (± 2) vs. 32.5 (±2.75) months. The main pattern of first progression was out of field progression: in-field progression alone occurred in 7 patients (12%) and with synchronous regional/distant progression in 10 patients (17%. In all patients, chemotherapy was withheld until progression post-SABR. Treatment was well tolerated; only one patient experienced grade 3 bronchial toxicity, three months after completion of SABR. CONCLUSIONS: SABR achieves high rates of local control with limited toxicities in patients with lung oligometastatic disease from a colorectal primary. This retrospective data indicates that patients with newly diagnosed lung oligometastatic disease may be safely treated with SABR as first treatment, with chemotherapy held in reserve. In heavily pretreated patients, SABR may allow patients a treatment break from systemic therapy, which may be beneficial both psychologically and physically. Future randomized SABR studies should evaluate sequencing of chemotherapy, the role of immunotherapies, and the quality of life of patients undergoing SABR.