Purpose: Identifying the target region is critical for successfully treating ventricular tachycardia (VT) with single fraction stereotactic arrhythmia radioablation (STAR). We report the feasibility of target definition based on direct co-registration of electroanatomic maps (EAM) and radioablation planning images. Materials and methods: The EAM consists of 3D cardiac anatomy representation with electrical activity at endocardium and is acquired by a cardiac electrophysiologist (CEP) during electrophysiology study. The CEP generates an EAM using a 3D cardiac mapping system anticipating radioablation planning. Our in-house software read these non-DICOM EAMs, registered them to a planning image set, and converted them to DICOM structure files. The EAM based target volume was finalized based on a consensus of CEPs, radiation oncologists and medical physicists, then expanded to ITV and PTV. The simulation, planning, and treatment is performed with a standard STAR technique: a single fraction of 25 Gy using volumetric-modulated arc therapy or dynamic conformal arc therapy depending on the target shape. Results: Seven patients with refractory VT were treated by defining the target based on registering EAMs on the planning images. Dice similarity indices between reference map and reference contours after registration were 0.814 +/- 0.053 and 0.575 +/- 0.199 for LV and LA/RV, respectively. Conclusions: The quality of the transferred EAMs on the MR/CT images was sufficient to localize the treatment region. Five of 7 patients demonstrated a dramatic reduction in VT events after 6 weeks. Longer follow-up is required to determine the true safety and efficacy of this therapy using EAM-based direct registration method.

Purpose/Objective(s)Non-small cell lung carcinoma (NSCLC) represents a diverse array of malignancies with the primary histologic subtypes of adenocarcinoma (ADC) and squamous cell carcinoma (SCC). Nearly one third of patients diagnosed with NSCLC will present with stage III disease. In patients with unresectable disease, the current standard is definitive chemoradiotherapy (CRT) followed by immunotherapy. Even though the systemic therapeutic landscape has changed based on histological subtype, radiation treatment remains the same for all NSCLC. Also it remains unclear whether certain clinicopathologic factors are associated with either histology or if histology influences survival outcomes following definitive CRT. Therefore, we analyzed the national cancer database (NCDB) to compare overall survival (OS) in Stage III NSCLC patients with ADC and SCC treated with definitive CRT.Materials/MethodsWe queried the NCDB for patients diagnosed with Stage III ADC or SCC of the lung between the years 2004 – 2015 who were treated non-surgically with concurrent CRT to a definitive dose (60-74 Gy). Univariable and multivariable analyses identified characteristics predictive of OS. Survival was calculated using Kaplan Meier method. Multivariable logistic regression was performed to identify clinicopathologic variables associated with each histology.ResultsUltimately 17,015 Stage III NSCLC patients with either SCC (n=9,406) or ADC (n=7,609) were eligible for analysis. Univariable analysis demonstrated a median OS of 24 months and 20 months (p<0.0001) and 3-year OS rates of 36% and 30% (p<0.0001) in patients diagnosed with ADC and SCC, respectively. Patients with SCC were more likely to be older (OR: 1.14, 95% CI: 1.07-1.23), have higher comorbidity scores (OR: 1.60, 95% CI: 1.43-1.80), left sided tumors (OR: 1.23, 95% CI: 1.14-1.31), and T4 lesions [OR: 2.68, 95% CI: 2.40-2.99, (p<0.0001, for all)]. Patients with SCC were less likely to have N2 (OR: 0.83, 95% CI: 0.72-0.94) or N3 disease (OR: 0.53, 95% CI: 0.46-0.62) and to receive treatment at an academic treatment facility (OR: 0.90, 95% CI: 0.84-0.97). Younger age, lower comorbidity score, higher radiation dose (i.e. ≥ 70 Gy), female sex, lower T stage, lower N stage, and ADC histology were associated with improved OS on multivariable comparison (p<0.01, for all).ConclusionCompared to ADC, SCC was associated with higher T stage, lower N stage, older patients with greater comorbidity scores, and left sided tumors. Both median, as well as, 3-year and 5-year OS rates were inferior in patients with SCC compared to ADC. Prospective studies are needed to validate these findings and potentially identify radiotherapeutic strategies that may improve outcomes in this histologic subset.

To test the hypothesis that dynamic conformal arc therapy (DCAT) in Monaco, compared with volumetric modulated arc therapy (VMAT), maintains plan quality with higher delivery efficiency for lung stereotactic body radiotherapy (SBRT) and to investigate dosimetric benefits of DCAT with active breath-hold (DCAT+ABH), compared with free-breathing (DCAT+FB) for varying tumor sizes and motions. Fifty DCAT plans were used for lung SBRT. Randomly selected 17 DCAT plans were evaluated with respect to the retrospectively generated volumetric modulated arc therapy (VMAT) plans. The maximum dose at 2 cm from planning target volume (PTV) in any direction (D2cm/Rx), the ratio of 50% prescription isodose volume to the PTV (R50%), conformity index (CI), the lung volume receiving ≥20 Gy (V20), and monitor unit (MU) were evaluated. A t-test was used to evaluate the difference of plan quality between DCAT and VMAT. Internal target volume (ITV)/integrated-gross target volume (GTV) attributed by intra-fraction motion and lung V20 were stratified for DCAT+ABH and DCAT+FB across varying GTVs. DCAT maintained plan quality (p = 0.154 for D2cm/Rx, p = 0.089 for R50%, p = 0.064 for CI, and p = 0.780 for lung V20) while reducing MUs up to 30% (p <0.001) from 2748 MU (VMAT) to 1868 MU (DCAT). DCAT+ABH, compared to DCAT+FB, reduced tumor motion, resulting in 19% volume reduction of PTV and 60% reduction in lung V20, on average. The difference in lung V20 between DCAT+ABH and DCAT+FB increased as the target size increased. The DCAT is a favorable approach compared with VMAT. These results support the utility of DCAT as a routine planning platform for lung SBRT, especially when utilized with respiratory motion management using the ABH.

Background:Verrucous carcinoma of the larynx (VCL) is a rare form of laryngeal squamous cell carcinoma. We analyzed the National Cancer Database (NCDB) to examine national treatment pattern, identify factors associated with primary radiation therapy (RT), and compare outcomes in patients with Tis-T2 N0 VCL treated primary surgery and primary RT. Methods:We accessed the NCDB from 2004 to 2015 for patients with Tis-T2 N0 VCL and recorded the treatment modality employed. Multivariable logistic regression was used to identify predictors for radiation therapy. Cox regression was used to calculate hazard ratios for survival. A propensity score matched Kaplan-Meier analysis compared primary surgical treatment to definitive radiation. Results:We identified 732 patients with laryngeal verrucous carcinoma from the NCDB. The majority were cTis-T2 (87%) N0 (96%). We identified 286 vs. 110 Tis-T2N0 patients treated primary surgery and with definitive radiation, respectively, for the purpose of this study. Predictors of radiation were treatment at a community center, no insurance, and higher T stage. Cox regression identified increased age, higher comorbidity score, and government insurance as predictive of worse survival. Propensity matching revealed a trend toward worse survival with definitive radiation, with a median survival of 98 months compared to 143 months (p= 0.02). When including only T1-2 lesions, that is, invasive disease, the trend toward increased survival with surgery [98 months vs. 135 months (p= 0.08)] persisted. Conclusion:The results of the present study support the use of surgery in the management of Tis-T2 N0 VCL when organ preservation is possible.

Sarcomatoid squamous cell carcinoma of the larynx is a rare entity comprising <1% of diagnoses. Case reports/series report a more aggressive disease course and call for more aggressive therapy, though data in this realm are lacking.

Purpose Radiation therapy remains an important palliative tool for patients with bone metastases. The guidelines from the American Society for Therapeutic Radiation Oncology recommend the use of fewer fractions based on randomized data. We used the National Cancer Database to examine trends in radiation fractionation for patients with bone metastases. Methods and Materials We queried breast, prostate, and non-small cell lung cancer in the National Cancer Database from 2010 to 2015 for patients with bone metastases at the time of diagnosis who received bone-directed radiation therapy of 8 Gy in 1 fraction, 20 Gy to 24 Gy in 5 to 6 fractions, 30 Gy in 10 fractions, or >30 Gy in 10 fractions. We tabulated the baseline characteristics, and a multivariable logistic regression analysis was used to identify predictors of single-fraction treatment. Results We identified 17,859 patients who met the study criteria. The median patient age was 67 years, and the majority of patients (67%) had primary prostate cancer. Most patients (62%) received spine treatment. Single-fraction treatment increased over time from 3% in 2010 to 7% by 2015. Use of more protracted courses (>30 Gy in 10 fractions) decreased from 34% to 15% over the same interval. The most commonly used regimen (50%-60% of cases) remained 30 Gy in 10 fractions. Predictors of single-fraction treatment included increased age, no systemic therapy, increasing distance from facility, treatment at an academic center, nonspine/nonskull metastasis, and more recent treatment year. Conclusions Use of single-fraction radiation for bone metastases has increased steadily but still accounts for <10% of palliative courses. The use of more protracted regimens has decreased significantly, although 30 Gy in 10 fractions remains the most widely used regiment.

Purpose: Definitive radiotherapy remains a primary treatment option for early stage glottic cancer. Intensity-modulated radiation therapy (IMRT) has emerged as the standard treatment technique for advanced head and neck cancers, whereas three-dimensional conformal radiotherapy (3D-CRT) has remained standard for early glottic cancers. We used the National Cancer Database (NCDB) to identify predictors of IMRT use and effect on outcome in these patients. Materials and Methods: We queried the NCDB from 2004-2015 for squamous cell carcinoma of the glottic larynx staged Tis-T2N0 treated with radiation alone. Logistic regression was used to identify predictors of IMRT. Cox regression was used to identify factors predictive of overall survival. Propensity matching was conducted to account for indication bias. Results: We identified 15,627 patients, of which 11% received IMRT. IMRT use rose from 2% in 2004 to 16% in 2015. Predictors of IMRT include: increased comorbidity, T2 stage, urban location, chemotherapy, treatment at an academic center, and later treatment year. Predictors of improved survival were female gender, higher income, lower stage, no chemotherapy, academic facility, and more remote year. There was no difference in survival between 3D-CRT and IMRT across all stages. Conclusions: The rate of IMRT use for early stage glottic laryngeal cancer has increased over time. There was no difference in outcome in patients receiving IMRT versus 3D-CRT across the cohort.

Objective: The COVID-19 pandemic necessitated drastic and rapid changes throughout the field of radiation oncology, some of which were unique to the discipline of radiosurgery. Guidelines called for reduced frame use and reducing the number of fractions. Our institution implemented these guidelines, and herein we show the resultant effect on patient treatments on our Gamma Knife Icon program. Methods: In early March 2020 we rapidly implemented suggested changes according to ASTRO and other consensus guidelines as they relate to stereotactic radiosurgery in the COVID-19 era. We reviewed the GK Icon schedule at our institution between January 01 and April 30, 2020. We documented age, condition treated, technique (frame vs. mask), and number of fractions. We then tabulated and graphed the number of patients, framed cases, and fractions delivered. Results: Seventy-seven patients were treated on the GK Icon over that period, for a total of 231 fractions. The number of unique patients varied from 18 (April) to 22 (January). Of the 77 patients only 5 were treated using a frame. The number of fractions per month decreased significantly over time, from 70 in January to 36 in April. Likewise, the percentage of single fraction cases increased from 4.5% per month in January to 67% in April. Conclusions: The results presented here show that it is possible to quickly and efficiently change work flows to allow for reduced fractionation and frame use in the time of a global pandemic. Multidisciplinary cooperation and ongoing communication are integral to the success of such programs.

Definitive radiation remains a treatment option for early stage glottic larynx cancer. Intensity modulated radiation therapy (IMRT) has been the standard treatment for more advanced head and neck cancers, while 3D conformal radiotherapy (3D CRT) has remained standard for early glottic cancers. We used the National Cancer Database (NCDB) to identify predictors of IMRT use and effect on outcome in these patients.

Background Surgery is the standard of care for early stage non‐small cell lung cancer (NSCLC). Stereotactic body radiotherapy (SBRT) is another definitive treatment option for those patients who have not been treated surgically. Comparison of approaches is being explored in NSCLC, but has yet to be compared exclusively in large cell neuroendocrine carcinoma (LCNEC) of the lung. We used the National Cancer Database (NCDB) to conduct such a comparison. Methods We accessed the NCDB for patients with LCNEC who were recorded as having lung stage T1‐2N0M0 treated with lobectomy/pneumonectomy or SBRT. Multivariable logistic regression identified predictors of SBRT. Multivariable Cox regression was used to identify predictors of survival propensity matching and account for indication bias. Results A total of 3209 patients met the criteria, of which 238 (7%) received SBRT. The median SBRT dose was 50 Gy (48–60) in four fractions (3–5). Predictors of SBRT were age >68, T1 disease, and most recent year of treatment. Predictors of survival were younger age, surgical treatment, female sex, and T1 disease. After propensity matching, median survival was 57 months versus 35 months in favor of surgical resection, P < 0.0001. Conclusion Surgical resection in comparison to SBRT has improved survival for patients with early stage LCNEC of the lung. SBRT represents a viable treatment alternative for those patients who do not meet the criteria for surgery.

e21073 Background: Large cell neuroendocrine carcinoma (LCNEC) is a rare pulmonary malignancy with clinicopathologic features of both non-small cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). The optimal treatment approach for LCNEC is not well established, likely a result of the histology’s underrepresentation in randomized clinical trials. Given the paucity of available data regarding LCNEC management, we queried the National Cancer Database (NCDB) to describe trends in management, identify predictors of treatment receipt, and compare outcomes in patients receiving chemotherapy (ChT) and chemoradiotherapy (CRT). Methods: We identified patients with locally advanced (Stage III) LCNEC of the lung treated with definitive ChT or CRT between the years of 2004-2015. Odds ratios were calculated to determine predictors of CRT receipt. Multivariable cox regression was used to determine predictors of overall survival. Results: Using the above criteria, 6,802 patients were identified, 46% of whom received CRT (n = 3,153) while 39% (n = 2,644) received ChT alone. Median age of the entire cohort was 68 years old. Most patients had T4 (35%) and N2 (59%) disease. Median overall survival was 11.9 months (11.3-12.6) in patients receiving ChT compared to 16.1 months (15.4-16.9) in patients receiving CRT (p < 0.0001). Overall survival at 1, 3, and 5 years was 50%, 20%, and 13% versus 60%, 27%, and 18%, in patients receiving ChT and CRT, respectively. Older patients and those with higher comorbidity scores were less likely to receive CRT; whereas patients with higher education level, treatment receipt at an academic/research program facility, N2 disease, and later treatment year were more likely to receive CRT. On multivariable analysis, older age, greater comorbidity score, presence of N2 disease, and presence of T4 disease were all associated with decreased OS, whereby female sex, private insurance, higher income, lower T stage, and more recent treatment were associated with increased overall survival. CRT receipt was an independent predictor of increased overall survival. Conclusions: Definitive CRT was an independent predictor of increased overall survival in patients with locally advanced LCNEC of the lung. Findings from our study may help guide potential areas of future investigation to help define an ideal treatment approach for LCNEC.

Abstract PURPOSE The COVID-19 pandemic necessitated drastic and rapid changes throughout the field of radiation oncology, some of which were unique to the discipline of radiosurgery. Available guidelines called for reduced frame use, postponing non-urgent cases, and reducing the number of fractions delivered. Our institution enacted many of these guidelines, and herein we show the resultant effect on patient treatments on our Gamma Knife Icon system. METHODS & MATERIALS In early to mid-March of 2020 our institution rapidly implemented suggested changes according to ASTRO and other consensus guidelines as they relate specifically to stereotactic radiosurgery in the COVID-19 era. We reviewed the GK Icon schedule at our institution between January 01 and April 30, 2020. We documented age, condition treated, technique (frame vs. mask), and number of fractions. We then tabulated and graphed the number of patients, framed cases, and fractions across that time period. RESULTS Seventy-seven patients were treated on the GK Icon between January and April 2020, for a total of 231 fractions. The number of unique patients per month varied from 18 (April) to 22 (January). Of the 77 patients only 5 were treated using a frame. The number of fractions per month decreased significantly over time, from 70 in January to 36 in April. Likewise, the percentage of single fraction cases increased from 4.5% per month in January to 67% in April. CONCLUSIONS The results presented here show that it is possible to quickly and efficiently change work flows to allow for reduced fractionation and frame use in the time of a global pandemic. Multidisciplinary cooperation and ongoing communication are integral to the success of such programs.

AIM:Some patients with early stage large cell neuroendocrine carcinoma (LCNEC) of the lung are not surgical candidates and will be managed with radiotherapy. We used the national cancer database to identify predictors of stereotactic radiotherapy and compare outcomes.MATERIALS & METHODS:We queried national cancer database for T1-2N0 LCNEC treated with radiation. Logistic regression and Cox regression identified predictors of stereotactic ablative body radiotherapy (SABR) and survival, respectively.RESULTS:We identified 754 patients, with 238 (32%) treated with SABR. Predictors of SABR were distance to facility, no chemotherapy, academic center, T1 and recent year. After propensity matching, median survival was 34.7 months compared with 23.7 months in favor of SABR (p = 0.02).CONCLUSION:SABR for LCNEC has increased over time and was associated with improved survival.

Guideline-based cancer screening is crucial for early detection and improved patient outcomes. However, there are many barriers to effective cancer screening including insurance coverage, healthcare access, patient education/compliance, and physician non-adherence to established best practices. One solution to these barriers is to implement comprehensive community-based cancer screening events to provide increased access to care. From 2014-2019 we implemented a total of 35 comprehensive cancer screening events across 13 community sites. All screenings were performed by physician volunteers and were free-of-cost. Pre-screening questionnaires were completed to evaluate qualifying screenings, compliance with primary care, and incidence of past screenings. Screening sites included skin (total skin check), head and neck (laryngoscopy), breast (mammogram and exam), cervical (PAP spear), colorectal (FIT test), prostate (PSA and DRE), and lung (low dose CT). A report of results was given to the patient with counseling done at the time of abnormal screening results. Additionally, reports were sent to primary care physicians and appropriate sub-specialty referrals were placed. A total of 4835 cancer screenings were performed on 1972 individual patients. Median age was 65 with 58.7% female and 41.3% male. A total of 1040 (21.5%) of individual screenings had an abnormal result. Abnormal results were highest with skin (40.9%) and lung (36.7%) subsites (P<0.05). Abnormal results were lowest with colorectal (3.1%) and cervical (6.6%) subsites. Patient satisfaction surveys were completed with a majority indicating excellent/good quality of screenings. Large scale community-based cancer screenings are feasible and yield a significant proportion of abnormal results. Further investigation is underway to evaluate follow up compliance, false positive/negative rate, treatment related outcomes, patient satisfaction and cost effectiveness.Tabled 1Abstract 2873; TableScreeningabnormalnormaltotal% abnormalSkin659951161040.9%H&N6341948213.1%Mammogram5315120426.0%Breast exam324364686.8%Cervical436126556.6%Colorectal144324463.1%DRE7831639419.8%PSA4338342610.1%Lung CT559515036.7%Total10403795483521.5% Open table in a new tab

Clinical use of stereotactic body radiation therapy (SBRT) has increased dramatically over the last 2 decades and is the current standard-of-care in cases of inoperable early stage non-small-cell lung cancer. While surgical resection remains the standard-of-care for operable patients, several ongoing clinical trials are investigating the role of SBRT in these operative candidates as well. Taking into consideration the expanding role and utility of SBRT, this paper will: review the historical basis of SBRT; examine landmark trials establishing the framework for the current body of evidence; discuss areas of active and future research; and identify epidemiological trends that are likely to further increase the use of SBRT.

There is an ongoing debate of surgical resection versus stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer. However, no study to date has compared these modalities for early-stage bronchopulmonary carcinoid tumors. The National Cancer Database was queried for histologically-confirmed T1-2N0M0 typical carcinoid tumors. Additional exclusion criteria were lack of treatment, conventionally-fractionated radiotherapy, or postoperative radiotherapy. Multivariable logistic regression ascertained factors associated with SBRT delivery. Cox proportional hazards modeling examined factors associated with overall survival (OS). Kaplan-Meier OS analysis was performed following propensity matching. Of 6,276 patients, 98.7% underwent resection (most commonly bi/lobectomy (67%) or sublobar resection (31%)) and 1.3% underwent SBRT (median dose/fractionation of 50 Gy in 4 fractions). Patients receiving SBRT were older, had greater comorbidities, and lower income (p<0.05 for all). Median follow-up had not been reached. SBRT was associated with poorer OS on Cox multivariate analysis (p<0.001). Following propensity matching, median OS was not reached in either group; respective mean and 5-year OS were 95.6 months and 87%, versus 68.8 months and 79% (p<0.001). Differences between cohorts persisted when removing patients who underwent SBRT specifically owing to surgical contraindications (p<0.001). Surgical resection should remain the cornerstone of therapy for early-stage bronchopulmonary carcinoid tumors. For inoperable cases, SBRT also produces acceptable survival and should be preferred over conventionally-fractionated radiotherapy. However, because causation cannot be implied in any retrospective comparison of surgery versus SBRT, investigations evaluating cancer-related endpoints are required to corroborate these results.

Objectives: Large cell neuroendocrine carcinoma (LCNEC) of the lung is a rare pulmonary tumor, having similar natural history and management strategy as small cell lung cancer. Therefore, the management of brain metastases in these patients has mirrored that of SCLC through the use of whole brain radiation therapy (WBRT). We used the National Cancer Database (NCDB) to look at predictors of stereotactic radiosurgery (SRS) and any potential differences in outcomes for patients with brain metastases from LCNEC. Material and methods: We queried the NCDB from 2004 to 2015 for patients with LCNEC of the lung with brain metastases that received brain radiation. Univariable and multivariable analyses were performed to identify factors predictive of SRS use and overall survival (OS). Propensity-adjusted Cox proportional hazard ratios for survival were used to account for indication bias. Results: Out of 9970 patients with LCNEC of the lung we identified 348 with brain metastases. Sixty-eight patients were treated with upfront SRS and 280 were treated with WBRT. Patients that were treated at an academic facility or received chemotherapy as part of upfront treatment were more likely to receive SRS. Univariable analysis revealed improved outcomes with SRS compared to WBRT, with a median OS of 11 months compared to 6 months, respectively (p = .007). Multivariable Cox regression with propensity score confirmed SRS to have improved survival (HR: 0.68, 95%CI: 0.51-0.91, p = .0093). Multivariable Cox regression with propensity score also identified younger age, receipt of chemotherapy, absence of extracranial disease and non-rural locations as additional predictors of improved OS. Conclusions: Treatment of brain metastases from LCNEC of the lung with SRS was associated with improved survival. For the appropriate patients, upfront treatment of limited brain metastases with SRS may be appropriate.