Comparing outcomes of concurrent chemotherapy regimens in patients 65 years old or older with locally advanced oropharyngeal carcinoma.

BACKGROUND: The comparative efficacy of cisplatin (CDDP), carboplatin, and cetuximab (CTX) delivered concurrently with radiation for locally advanced oropharyngeal squamous cell carcinoma continues to be evaluated. METHODS: The linked Surveillance, Epidemiology, and End Results-Medicare database was used to identify and compare patient and disease profiles, mortality, toxicity, and overall cost for patients with oropharynx cancer undergoing definitive concurrent chemoradiation with CDDP, carboplatin, or CTX between 2006 and 2011. The human papillomavirus status was unknown. The primary outcome was 2-year overall survival (OS). RESULTS: Four hundred nine patients receiving concurrent CDDP (n = 167), carboplatin (n = 69), or CTX (n = 173) were included. Those who were older, those who were nonwhite, and those with a Charlson Comorbidity Index ≥ 2 were less likely to receive CDDP. Two-year OS was inferior with CTX (hazard ratio [HR], 1.68; 95% confidence interval [CI], 1.08-2.60; P = .020) and no different with carboplatin (HR, 1.31; 95% CI, 0.73-2.35; P = .362) in a Cox proportional hazards model (reference CDDP). There was no statistically significant difference between carboplatin and CTX (HR, 1.28; 95% CI, 0.77-2.14; P = .891). Rates of antiemetic use and hospital visits for nausea/emesis/diarrhea or dehydration were statistically higher with CDDP. Pneumonia rates were higher with carboplatin. In the multivariate model, the corrected mean per-patient spending was significantly higher for CTX and carboplatin than CDDP ($61,133 and $65,721 vs $48,709). CONCLUSIONS: Patients who received CDDP had improved OS. CDDP was also associated with slightly lower overall costs and higher antiemetic usage and hospital visit rates, although a strong selection bias was observed because those receiving CTX and carboplatin were older and had higher comorbidity scores.

Impact of facility volume on outcomes in patients with squamous cell carcinoma of the anal canal: Analysis of the National Cancer Data Base.

BACKGROUND: Given the rarity of anal cancer and the technical aspects involved in radiation (RT) planning, the authors conducted a population-based analysis evaluating the impact of radiation oncology facility volume on overall survival (OS) in patients with squamous cell carcinoma (SCC) of the anal canal. METHODS: The National Cancer Data Base (NCDB) was queried for patients with SCC of the anal canal who underwent RT. All patients were coded as having received their entire course of RT at the NCDB reporting facility. Facility volume was categorized into tertiles (low, intermediate, and high) and was based on the number of times a facility's unique identification code appeared. RESULTS: In total, 13,550 patients were identified. Patients who received treatment at higher volume radiation oncology facilities had longer OS based on multivariate analysis (MVA) (hazard ratio, 0.81; 95% confidence interval [CI], 0.73-0.90; P < .001) and propensity score matching analysis (hazard ratio, 0.79; 95% CI, 0.69-0.91; P < .001). For patients who received treatment at low-volume, intermediate-volume, and high-volume centers, the 5-year OS rate was 70%, 72.2%, and 75.4%, respectively (P < .001). Compared with low/intermediate-volume radiation oncology centers, high-volume centers were more likely to treat patients with concurrent chemotherapy (odds ratio, 1.27; 95% CI, 1.07-1.51; P = .006) and less likely to have treatment delays leading to an RT duration of >45 days (odds ratio, 0.74; 95% CI, 0.69-0.80; P < .001). CONCLUSIONS: Treatment at higher volume radiation oncology centers appears to be associated with improved OS in patients with SCC of the anal canal. These results likely reflect the relation between physician experience and delivery of high-quality RT, which perhaps is best evident in rare tumors such as anal SCC. Cancer 2017;123:228-236. © 2016 American Cancer Society.

A comprehensive comparative analysis of treatment modalities for sinonasal malignancies.

BACKGROUND: Sinonasal malignancies are a rare and heterogeneous group of tumors for which there is a paucity of robust data with which to guide management decisions. The authors used the National Cancer Data Base to better understand the presenting characteristics of these tumors and to compare outcomes by treatment modality. METHODS: The National Cancer Data Base was queried for sinonasal malignancies diagnosed between 2004 and 2012. Overall survival was assessed using multivariate analyses and propensity score matching. RESULTS: A total of 11,160 patients were identified for the initial analysis. The majority were male, aged 40 to 69 years, with tumors of the nasal cavity or maxillary sinus. Squamous cell histology was most common. The majority of patients presented with advanced tumor stage but without locoregional lymph node or distant metastases. Treatment modalities were compared for squamous cell carcinomas. In multivariate analysis, compared with surgery alone, patients who received adjuvant radiotherapy (hazard ratio [HR], 0.658 [P<.001]), adjuvant chemoradiotherapy (HR, 0.696 [P = .002]), or neoadjuvant therapy (HR, 0.656 [P = .007]) had improved overall survival. Patients who received radiotherapy alone (HR, 1.294 [P = .001]) or chemotherapy alone (HR, 1.834 [P<.001]) had worse outcomes. These findings were validated in propensity score matching. It is important to note that neoadjuvant chemoradiotherapy was associated with achieving a negative surgical margin (odds ratio, 2.641 [P = .045]). CONCLUSIONS: Surgery is the mainstay of therapy for patients with sinonasal malignancies, but multimodality therapy is associated with improved overall survival. Cancer 2017;123:3040-49. © 2017 American Cancer Society.

Adjuvant radiotherapy improves overall survival in patients with resected gastric adenocarcinoma: A National Cancer Data Base analysis.

BACKGROUND: For patients with resectable gastric adenocarcinoma, perioperative chemotherapy and adjuvant chemoradiotherapy (CRT) are considered standard options. In the current study, the authors used the National Cancer Data Base to compare overall survival (OS) between these regimens. METHODS: Patients who underwent gastrectomy for nonmetastatic gastric adenocarcinoma from 2004 through 2012 were divided into those treated with perioperative chemotherapy without RT versus those treated with adjuvant CRT. Survival was estimated and compared using univariate and multivariate models adjusted for patient and tumor characteristics, surgical margin status, and the number of lymph nodes examined. Subset analyses were performed for factors chosen a priori, and potential interactions between treatment and covariates were assessed. RESULTS: A total of 3656 eligible patients were identified, 52% of whom underwent perioperative chemotherapy and 48% of whom received postoperative CRT. The median follow-up was 47 months, and the median age of the patients was 62 years. Analysis of the entire cohort demonstrated improved OS with adjuvant RT on both univariate (median of 51 months vs 42 months; P = .013) and multivariate (hazard ratio, 0.874; 95% confidence interval, 0.790-0.967 [P = .009]) analyses. Propensity score-matched analysis also demonstrated improved OS with adjuvant RT (median of 49 months vs 39 months; P = .033). On subset analysis, a significant interaction was observed between the survival impact of adjuvant RT and surgical margins, with a greater benefit of RT noted among patients with surgical margin-positive disease (hazard ratio with RT: 0.650 vs 0.952; P for interaction <.001). CONCLUSIONS: In this National Cancer Data Base analysis, the use of adjuvant RT in addition to chemotherapy was associated with a significant OS advantage for patients with resected gastric cancer. The survival advantage observed with adjuvant CRT was most pronounced among patients with positive surgical margins. Cancer 2017;123:3402-9. © 2017 American Cancer Society.

A comparison of overall survival for patients with T4 larynx cancer treated with surgical versus organ-preservation approaches: A National Cancer Data Base analysis.

BACKGROUND: Although laryngectomy is the treatment of choice for patients with T4 larynx cancer, many patients are unable or unwilling to undergo laryngectomy and instead pursue larynx-preservation strategies combining radiotherapy (RT) and chemotherapy. Herein, the authors analyzed the National Cancer Data Base to evaluate overall survival (OS) between patients treated with surgical and organ-preserving modalities. METHODS: The National Cancer Data Base was queried for patients diagnosed from 2004 through 2012 with T4M0 laryngeal cancer who underwent either laryngectomy (surgery) with adjuvant RT (SRT), chemotherapy starting concurrently within 7 days of RT (CCRT), or multiagent induction chemotherapy starting 43 to 98 days before RT (ICRT). Multivariate analysis and propensity score matching were used to explore the association between the intervention and OS. Recursive partitioning analysis was performed to identify groups benefiting from particular modalities. RESULTS: A total of 1559 patients who underwent SRT, 1597 patients who underwent CCRT, and 386 patients who underwent ICRT were included. Adjusting for covariates, CCRT was found to be associated with inferior OS compared with SRT (hazard ratio [HR], 1.55; 95% confidence interval [95% CI], 1.41-1.70 [P<.01]) and with ICRT (HR, 1.25; 95% CI, 1.07-1.45 [P<.01]). OS among the patients treated with SRT did not appear to differ significantly from that of the ICRT cohort (HR, 0.87; 95% CI, 0.73-1.03 [P = 0.10]), a finding confirmed with propensity score matching. Recursive partitioning analysis identified no subset of patients that derived an OS benefit from either approach over the other. CONCLUSIONS: OS among patients undergoing SRT was found to be superior to that of patients treated with CCRT but did not significantly differ from that of those undergoing ICRT. Because these intriguing findings require validation, SRT should remain the standard of care for patients with this disease. However, organ preservation with ICRT may be a reasonable alternative in certain patients. Cancer 2017;123:600-608. © 2016 American Cancer Society.

Survival outcomes with concurrent chemoradiation for elderly patients with locally advanced head and neck cancer according to the National Cancer Data Base.

BACKGROUND: The overall survival (OS) benefit of concurrent chemoradiotherapy (CRT) for head and neck squamous cell carcinoma patients older than 70 years is debated. This study examines the outcomes of elderly patients receiving CRT versus radiotherapy (RT) alone. METHODS: The National Cancer Data Base was queried for patients older than 70 years with nonmetastatic oropharyngeal, laryngeal, or hypopharyngeal cancer (T3-4 or N(+)). CRT was defined as chemotherapy started within 14 days of the initiation of RT. Univariate analysis, multivariate analysis (MVA), propensity score matching (PSM), and recursive partitioning analysis (RPA) were performed. RESULTS: The study included 4042 patients: 2538 (63%) received CRT. The median follow-up was 19 months. The unadjusted median OS was longer with the addition of CRT (P < .001). OS was superior with CRT in the MVA (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.58-0.68; P < .001) and PSM analyses (HR, 0.73; 95% CI, 0.66-0.80; P < .001) in comparison with RT alone. According to RPA, CRT was associated with longer OS for patients 81 years or younger with low comorbidity scores and either T1-2/N2-3 disease or T3-4/N0-3 disease. The survival benefit with CRT disappeared for 2 subgroups in the 71- to 81-year age range: those with T1-2, N1, and Charlson-Deyo 0-1 (CD0-1) disease and those with T3-4, N1+, and CD1+ disease. Patients who were older than 81 years did not have increased survival with CRT. The receipt of CRT was associated with a longer duration of RT (odds ratio, 1.74; 95% CI, 1.50-2.01; P < .001). CONCLUSIONS: Patients older than 70 years should not be denied concurrent chemotherapy solely on the basis of age; additional factors, including the performance status and the tumor stage, should be taken into account. Cancer 2016;122:1533-43. © 2016 American Cancer Society.

Improved survival with combined modality therapy in the modern era for primary mediastinal B-cell lymphoma.

Primary mediastinal B-cell lymphoma (PMBCL) is an uncommon lymphoma for which existing data is limited. We utilized the National Cancer Database (NCDB) to evaluate PMBCL and the impact of radiotherapy (RT) on outcomes in the years following FDA approval of rituximab. We queried the NCDB for patients with PMBCL diagnosed from 2006 to 2011 and treated with multiagent chemotherapy. Kaplan-Meier overall survival (OS) estimates, univariate (UVA), and multivariate (MVA) Cox proportional hazards regression analyses were performed. Propensity score matched analysis (PSMA) was performed to account for indication bias and mitigate heterogeneity between treatment groups. 465 patients were identified with a median follow-up of 36 months. Median age was 36 years; 43% received RT. 5-year OS for the entire cohort was 87%, and for the no-RT and RT groups, 83% versus 93%, respectively. On UVA, OS was improved with RT (HR 0.34, P = 0.002). On MVA, RT remained significantly associated with improved OS (HR 0.44, P = 0.028) while Medicaid insurance status and increasing stage remained significantly associated with OS decrement. PSMA confirmed the OS benefit associated with RT. This analysis is the largest PMBCL dataset to date and demonstrates a significant survival benefit associated with RT in patients receiving multiagent chemotherapy in the rituximab era. More than half of patients treated in the United States during this time period did not receive RT. In the absence of phase III data to support omission, combined modality therapy with its associated survival benefit should be the benchmark against which other therapies are compared.

Association of health insurance with outcomes in adults ages 18 to 64 years with melanoma in the United States.

BACKGROUND: Studies evaluating insurance status and melanoma outcomes are limited. OBJECTIVE: We investigated whether health insurance correlates with more advanced disease, receipt of treatment, and survival in melanoma. METHODS: This was a cross-sectional analysis of 61,650 patients with cutaneous melanoma using the Surveillance, Epidemiology, and End Results database. RESULTS: Under multivariate analysis, patients with either Medicaid insurance (hazard ratio, 1.83; 95% confidence interval [CI], 1.65-2.04; P < .001) or uninsured status (hazard ratio, 1.63; 95% CI, 1.44-1.85; P < .001) were more likely to die of any cause, including melanoma. Uninsured compared with non-Medicaid insured cases more often presented with increasing tumor thickness (odds ratio [OR], 2.19; 95% CI, 1.76-2.73; P < .001) and presence of ulceration (OR, 1.64; 95% CI, 1.40-1.92; P < .001), and less often received treatment (OR, 1.87; 95% CI, 1.60-2.19; P < .001). Compared with non-Medicaid insured, Medicaid cases more often had increasing tumor thickness (OR, 2.36; 95% CI, 1.91-2.91; P < .001), advanced stage (OR, 1.59; 95% CI, 1.37-1.85; P < .001), and presence of ulceration (OR, 1.40; 95% CI, 1.19-1.63; P < .001), and less often received treatment (OR, 1.61; 95% CI, 1.37-1.89; P < .001). LIMITATIONS: This was a retrospective study. CONCLUSION: Patients with melanoma and Medicaid or uninsured status were more likely to present with advanced disease and were less likely to receive treatment, likely contributing to an overall and cause-specific survival detriment. Addressing access to care may help improve these outcomes.

Clinical and Dosimetric Impact of 2D kV Motion Monitoring and Intervention in Liver Stereotactic Body Radiation Therapy.

Purpose: Positional errors resulting from motion are a principal challenge across all disease sites in radiation therapy. This is particularly pertinent when treating lesions in the liver with stereotactic body radiation therapy (SBRT). To achieve dose escalation and margin reduction for liver SBRT, kV real-time imaging interventions may serve as a potential solution. In this study, we report results of a retrospective cohort of liver patients treated using real-time 2D kV-image guidance SBRT with emphasis on the impact of (1) clinical workflow, (2) treatment accuracy, and (3) tumor dose. Methods and Materials: Data from 33 patients treated with 41 courses of liver SBRT were analyzed. During treatment, planar kV images orthogonal to the treatment beam were acquired to determine treatment interventions, namely treatment pauses (ie, adequacy of gating thresholds) or treatment shifts. Patients were shifted if internal markers were >3 mm, corresponding to the PTV margin used, from the expected reference condition. The frequency, duration, and nature of treatment interventions (ie, pause vs shift) were recorded, and the dosimetric impact associated with treatment shifts was estimated using a machine learning dosimetric model. Results: Of all fractions delivered, 39% required intervention, which took on average 1.9 ± 1.6 minutes and occurred more frequently in treatments lasting longer than 7 minutes. The median realignment shift was 5.7 mm in size, and the effect of these shifts on minimum tumor dose in simulated clinical scenarios ranged from 0% to 50% of prescription dose per fraction. Conclusion: Real-time kV-based imaging interventions for liver SBRT minimally affect clinical workflow and dosimetrically benefit patients. This potential solution for addressing positional errors from motion addresses concerns about target accuracy and may enable safe dose escalation and margin reduction in the context of liver SBRT.

Fiducial Markers Allow Accurate and Reproducible Delivery of Liver Stereotactic Body Radiation Therapy.

Fiducial markers are utilized for image guided radiotherapy (IGRT) alignment during the delivery of liver stereotactic body radiosurgery (SBRT). There are limited data demonstrating the impact of matching fiducials on the accuracy of liver SBRT. This study quantifies the benefit of fiducial-based alignment and improvements in inter-observer reliability. Nineteen patients with 24 liver lesions were treated with SBRT. Target localization was performed using fiducial markers on cone-beam computed tomography (CBCT). Each CBCT procedure was retrospectively realigned to match both the liver edge and fiducial markers. The shifts were recorded by seven independent observers. Inter-observer variability was analyzed by calculating the mean error and uncertainty for the set-up. The mean absolute Cartesian error observed from fiducial and liver edge-based alignment was 1.5 mm and 5.3 mm, respectively. The mean uncertainty from fiducial and liver edge-based alignment was 1.8 mm and 4.5 mm, respectively. An error of 5 mm or greater was observed 50% of the time when aligning to the liver surface versus 5% of the time when aligning to fiducial markers. Aligning to the liver edge significantly increased the error, resulting in increased shifts when compared to alignment to fiducials. Tumors of 3 cm or farther from the liver dome had higher mean errors when aligned without fiducials (4.8 cm vs. 4.4 cm, p = 0.003). Our data support the use of fiducial markers for safer and more accurate liver SBRT.

Evaluation of variables predicting PFT changes for lung cancer patients treated on a prospective 4DCT-ventilation functional avoidance clinical trial.

PURPOSE: Functional avoidance radiotherapy uses functional imaging to reduce pulmonary toxicity by designing radiotherapy plans that reduce doses to functional regions of the lung. A phase-II, multi-center, prospective study of 4DCT-ventilation functional avoidance was completed. Pre and post-treatment pulmonary function tests (PFTs) were acquired and assessed pulmonary function change. This study aims to evaluate which clinical, dose and dose-function factors predict PFT changes for patients treated with 4DCT-ventilation functional avoidance radiotherapy. MATERIALS AND METHODS: 56 patients with locally advanced lung cancer receiving radiotherapy were accrued. PFTs were obtained at baseline and three months following radiotherapy and included forced expiratory volume in 1-second (FEV1), forced vital capacity (FVC), and FEV1/FVC. The ability of patient, clinical, dose (lung and heart), and dose-function metrics (metrics that combine dose and 4DCT-ventilation-based function) to predict PFT changes were evaluated using univariate and multivariate linear regression. RESULTS: Univariate analysis showed that only dose-function metrics and the presence of chronic obstructive pulmonary disease (COPD) were significant (p<0.05) in predicting FEV1 decline. Multivariate analysis identified a combination of clinical (immunotherapy status, presence of thoracic comorbidities, smoking status, and age), along with lung dose, heart dose, and dose-function metrics in predicting FEV1 and FEV1/FVC changes. CONCLUSION: The current work evaluated factors predicting PFT changes for patients treated in a prospective functional avoidance radiotherapy study. The data revealed that lung dose- function metrics could predict PFT changes, validating the significance of reducing the dose to the functional lung to mitigate the decline in pulmonary function and providing guidance for future clinical trials.

Characterizing Pulmonary Function Test Changes for Patients With Lung Cancer Treated on a 2-Institution, 4-Dimensional Computed Tomography-Ventilation Functional Avoidance Prospective Clinical Trial.

Purpose: Four-dimensional computed tomography (4DCT)-ventilation-based functional avoidance uses 4DCT images to generate plans that avoid functional regions of the lung with the goal of reducing pulmonary toxic effects. A phase 2, multicenter, prospective study was completed to evaluate 4DCT-ventilation functional avoidance radiation therapy. The purpose of this study was to report the results for pretreatment to posttreatment pulmonary function test (PFT) changes for patients treated with functional avoidance radiation therapy. Methods and Materials: Patients with locally advanced lung cancer receiving chemoradiation were accrued. Functional avoidance plans based on 4DCT-ventilation images were generated. PFTs were obtained at baseline and 3 months after chemoradiation. Differences for PFT metrics are reported, including diffusing capacity for carbon monoxide (DLCO), forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC). PFT metrics were compared for patients who did and did not experience grade 2 or higher pneumonitis. Results: Fifty-six patients enrolled on the study had baseline and posttreatment PFTs evaluable for analysis. The mean change in DLCO, FEV1, and FVC was -11.6% ± 14.2%, -5.6% ± 16.9%, and -9.0% ± 20.1%, respectively. The mean change in DLCO was -15.4% ± 14.4% for patients with grade 2 or higher radiation pneumonitis and -10.8% ± 14.1% for patients with grade <2 radiation pneumonitis (P = .37). The mean change in FEV1 was -14.3% ± 22.1% for patients with grade 2 or higher radiation pneumonitis and -3.9% ± 15.4% for patients with grade <2 radiation pneumonitis (P = .09). Conclusions: The current work is the first to quantitatively characterize PFT changes for patients with lung cancer treated on a prospective functional avoidance radiation therapy study. In comparison with patients treated with standard thoracic radiation planning, the data qualitatively show that functional avoidance resulted in less of a decline in DLCO and FEV1. The presented data can help elucidate the potential pulmonary function improvement with functional avoidance radiation therapy.

Dosimetric and deformation effects of image-guided interventions during stereotactic body radiation therapy of the prostate using an endorectal balloon.

PURPOSE: During stereotactic body radiation therapy (SBRT) for the treatment of prostate cancer, an inflatable endorectal balloon (ERB) may be used to reduce motion of the target and reduce the dose to the posterior rectal wall. This work assessed the dosimetric impact of manual interventions on ERB position in patients receiving prostate SBRT and investigated the impact of ERB interventions on prostate shape. METHODS: The data of seven consecutive patients receiving SBRT for the treatment of clinical stage T1cN0M0 prostate cancer enrolled in a multi-institutional, IRB-approved trial were analyzed. The SBRT dose was 50 Gy in five fractions to a planning target volume (PTV) that included the prostate (implanted with three fiducial markers) with a 3-5 mm margin. All plans were based on simulation images that included an ERB inflated with 60 cm(3) of air. Daily kilovoltage cone-beam computed tomography (CBCT) imaging was performed to localize the PTV, and an automated fusion with the planning images yielded displacements required for PTV relocalization. When the ERB volume and/or position were judged to yield inaccurate repositioning, manual adjustment (ERB reinflation and/or repositioning) was performed. Based on all 59 CBCT image sets acquired, a deformable registration algorithm was used to determine the dose received by, displacement of, and deformation of the prostate, bladder (BLA), and anterior rectal wall (ARW). This dose tracking methodology was applied to images taken before and after manual adjustment of the ERB (intervention), and the delivered dose was compared to that which would have been delivered in the absence of intervention. RESULTS: Interventions occurred in 24 out of 35 (69%) of the treated fractions. The direct effect of these interventions was an increase in the prostate radiation dose that included 95% of the PTV (D95) from 9.6 ± 1.0 to 10.0 ± 0.2 Gy (p = 0.06) and an increase in prostate coverage from 94.0% ± 8.5% to 97.8% ± 1.9% (p = 0.03). Additionally, ERB interventions reduced prostate deformation in the anterior-posterior (AP) direction, reduced errors in the sagittal rotation of the prostate, and increased the similarity in shape of the prostate to the radiotherapy plan (increased Dice coefficient from 0.76 ± 0.06 to 0.80 ± 0.04, p = 0.01). Postintervention decreases in prostate volume receiving less than the prescribed dose and decreases in the voxel-wise displacement of the prostate, bladder, and anterior rectal wall were observed, which resulted in improved dose-volume histogram (DVH) characteristics. CONCLUSIONS: Image-guided interventions in ERB volume and/or position during prostate SBRT were necessary to ensure the delivery of the dose distribution as planned. ERB interventions resulted in reductions in prostate deformations that would have prevented accurate localization of patient anatomy.

Population-level and individual-level explainers for propensity score matching in observational studies.

Precis: The exclusion of unmatched observations in propensity score matching has implications for the generalizability of causal effects. Machine learning methods can help to identify how the study population differs from the unmatched subpopulation. Background: There has been widespread use of propensity scores in evaluating the effect of cancer treatments on survival, particularly in administrative databases and cancer registries. A byproduct of certain matching schemes is the exclusion of observations. Borrowing an analogy from clinical trials, one can view these exclusions as subjects that do not satisfy eligibility criteria. Methods: Developing identification rules for these "data-driven eligibility criteria" in observational studies on both population and individual levels helps to ascertain the population on which causal effects are being made. This article presents a machine learning method to determine the representativeness of causal effects in two different datasets from the National Cancer Database. Results: Decision trees reveal that groups with certain features have a higher probability of inclusion in the study population than older patients. In the first dataset, younger age categories had an inclusion probability of at least 0.90 in all models, while the probability for the older category ranged from 0.47 to 0.65. Most trees split once more on an even higher age at a lower node, suggesting that the oldest patients are the least likely to be matched. In the second set of data, both age and surgery status were associated with inclusion. Conclusion: The methodology presented in this paper underscores the need to consider exclusions in propensity score matching procedures as well as complementing matching with other propensity score adjustments.

Results of a Multi-Institutional Phase 2 Clinical Trial for 4DCT-Ventilation Functional Avoidance Thoracic Radiation Therapy.

PURPOSE: Radiation pneumonitis remains a major limitation in the radiation therapy treatment of patients with lung cancer. Functional avoidance radiation therapy uses functional imaging to reduce pulmonary toxic effects by designing radiation therapy plans that reduce doses to functional regions of the lung. Lung functional imaging has been developed that uses 4-dimensional computed tomography (4DCT) imaging to calculate 4DCT-based lung ventilation (4DCT-ventilation). A phase 2 multicenter study was initiated to evaluate 4DCT-ventilation functional avoidance radiation therapy. The study hypothesis was that functional avoidance radiation therapy could reduce the rate of grade ≥2 radiation pneumonitis to 12% compared with a 25% historical rate, with the trial being positive if ≤16.4% of patients experienced grade ≥2 pneumonitis. METHODS AND MATERIALS: Lung cancer patients receiving curative-intent radiation therapy (prescription doses of 45-75 Gy) and chemotherapy were accrued. Patient 4DCT scans were used to generate 4DCT-ventilation images. The 4DCT-ventilation images were used to generate functional avoidance plans that reduced doses to functional portions of the lung while delivering the prescribed tumor dose. Pneumonitis was evaluated by a clinician at 3, 6, and 12 months after radiation therapy. RESULTS: Sixty-seven evaluable patients were accrued between April 2015 and December 2019. The median prescription dose was 60 Gy (range, 45-66 Gy) delivered in 30 fractions (range, 15-33 fractions). The average reduction in the functional volume of lung receiving ≥20 Gy with functional avoidance was 3.5% (range, 0%-12.8%). The median follow-up was 312 days. The rate of grade ≥2 radiation pneumonitis was 10 of 67 patients (14.9%; 95% upper CI, 24.0%), meeting the phase 2 criteria. CONCLUSIONS: 4DCT-ventilation offers an imaging modality that is convenient and provides functional imaging without an extra procedure necessary. This first report of a multicenter study of 4DCT-ventilation functional avoidance radiation therapy provided data showing that the trial met phase 2 criteria and that evaluation in a phase 3 study is warranted.

Genome sequences for five strains of the emerging pathogen Haemophilus haemolyticus.

We report the first whole-genome sequences for five strains, two carried and three pathogenic, of the emerging pathogen Haemophilus haemolyticus. Preliminary analyses indicate that these genome sequences encode markers that distinguish H. haemolyticus from its closest Haemophilus relatives and provide clues to the identity of its virulence factors.

Estimation of microscopic dose enhancement factor around gold nanoparticles by Monte Carlo calculations.

PURPOSE: An approach known as gold nanoparticle-aided radiation therapy (GNRT) is a recent development in radiation therapy which seeks to make a tumor more susceptible to radiation damage by modifying its photon interaction properties with an infusion of gold nanoparticles (GNPs). The purpose of this study was to quantify the energy deposition due to secondary electrons from GNPs on a nanometer scale and to calculate the corresponding microscopic dose enhancement factor around GNPs. METHODS: The Monte Carlo code EGSnrc was modified to obtain the spectra of secondary electrons from atoms of gold approximating GNPs and molecules of water under photon irradiation of a tumor loaded with GNPs. Six different photon sources were used: 125I, 103Pd, 169Yb, 192Ir, 50 kVp, and 6 MV x rays. Treating the scored electron spectra as point sources within an infinite medium of water, the event-by-event Monte Carlo code NOREC was used to quantify the radial dose distribution, giving rise to gold/water electron dose point kernels and corresponding microscopic dose enhancement factors. These kernels were applied to a test case based on a scanning electron microscope image of a GNP distribution in tissue, enabling the determination of the microscopic dose enhancement at each dose point. RESULTS: For the lower energy sources 125I, 103Pd, 169Yb, and 50 kVp, the secondary electron fluence within a GNP-loaded tumor was increased by as much as two orders of magnitude, leading to two orders of magnitude increase in electron energy deposition over radial distances up to 10 microm. For the test case considered, the dose was enhanced by factors ranging from 2 to 20 within 5 microm of GNPs, and by 5% as far away as 30 microm. CONCLUSIONS: This study demonstrates a remarkable microscopic dose enhancement due to GNPs and low energy photon sources. By quantifying the microscopic dose enhancement factor for a given photon source as a function of distance from GNPs, it also enables the selection of either a passive or an active tumor targeting strategy using GNPs which will maximize the radiobiological benefit from GNRT.

Optimizing Coded Aperture Imaging techniques to allow for online tracking of fiducial markers with high-energy scattered radiation from treatment beam.

PURPOSE: Real-time visualization of target motion using fiducial markers during radiation therapy treatment will allow for more accurate dose delivery. The purpose of this study was to optimize techniques for online fiducial marker tracking by detecting the scattered treatment beam through coded aperture imaging (CAI). Coded aperture imaging is a novel imaging technique that can allow target tracking in real time during treatment, and do so without adding any additional radiation dose, by making use of the scattered treatment beam radiation. METHODS: Radiotherapy beams of various energies, incident on phantoms containing gold fiducial markers were modeled using MCNP6.2 Monte Carlo transport code. Orthogonal scatter radiographs were collected through a CAI geometry. After decoding the simulated radiograph data, the centroid location and FWHM/SNR of the fiducial signals were analyzed. The effects of properties related to the CA (rank, pattern, and physical dimensions), detector (dimensions and pixel count), position (CA and phantom), and the incident beam (spectrum and direction) were investigated. These variables were evaluated by quantifying the positional accuracy, resolution, and SNR of the fiducials' signal. The effects of phantom scatter and decoding artifacts were reduced via Fourier filtering to avoid treatment interruption and physical interaction with the coded mask. RESULTS: The method was able to accurately localize the markers to within 1 pixel of a simulated radiograph. A 10 × 10 × 2 cm tungsten mask was chosen to attenuate >99 % of incident scatter through opaque elements, while minimizing collimation artifacts which arise from vignetting of the coded radiograph. Clear separation of centroids from fiducial signals with 2.5 mm separation was maintained, and initial optimization of parameters has produced an aperture which decodes the location of multiple fiducial markers inside a human phantom properly with a high SNR in the final radiograph image. CONCLUSION: Current results show a proof of concept for a novel real-time imaging method. Coded aperture imaging is a promising technique for extracting the fiducial scatter signal from a broader Compton-scatter background. These results can be used to further optimize the CAI parameter space and guide fabrication and testing of a clinical device.

Simulation of x-ray-induced acoustic imaging for absolute dosimetry: Accuracy of image reconstruction methods.

PURPOSE: Three-dimensional in-vivo dose verification is one of the standing challenges in radiation therapy. X-ray-induced acoustic tomography has recently been proposed as an imaging method for use in in-vivo dosimetry. The aim of this study was to investigate the accuracy of reconstructing three-dimensional (3D) absolute dose using x-ray-induced acoustic tomography. We performed this investigation using two different tomographic dose reconstruction techniques. METHODS: Two examples of 3D dose reconstruction techniques for x-ray acoustic imaging are investigated. Dose distributions are calculated for varying field sizes using a clinical treatment planning system. The induced acoustic pressure waves which are generated by the increase in temperature due to the absorption of pulsed MV x-rays are simulated using an advanced numerical modeling package for acoustic wave propagation in the time domain. Two imaging techniques, back projection and iterative time reversal, are used to reconstruct the 3D dose distribution in a water phantom with open fields. Image analysis is performed and reconstructed depth dose curves from x-ray acoustic imaging are compared to the depth dose curves calculated from the treatment planning system. Calculated field sizes from the reconstructed dose profiles by back projection and time reversal are compared to the planned field size to determine their accuracy. The iterative time reversal imaging technique is also used to reconstruct dose in an example clinical dose distribution. Image analysis of this clinical test case is performed using the gamma passing rate. In addition, gamma passing rates are used to validate the stopping criteria in the iterative time reversal method. RESULTS: Water phantom simulations showed that back projection does not adequately reconstruct the shape and intensity of the depth dose. When compared to the depth of maximum dose calculated by a treatment planning system, the maximum dose depth by back projection is shifted deeper by 55 and 75 mm for 4 × 4 cm and 10 × 10 cm field sizes, respectively. The reconstructed depth dose by iterative time reversal accurately agrees with the planned depth dose for a 4 × 4 cm field size and is shifted deeper by 12 mm for the 10 × 10 cm field size. When reconstructing field sizes, the back projection method leads to 18% and 35% larger sizes for the 4 × 4 cm and 10 × 10 cm fields, respectively, whereas the iterative time reversal method reconstructs both field sizes with < 2% error. For the clinical dose distribution, we were able to reconstruct the dose delivered by a 1 degree sub-arc with a good accuracy. The reconstructed and planned doses were compared using gamma analysis, with> 96% gamma passing rate at 3%/2 mm. CONCLUSIONS: Our results show that the 3D x-ray acoustic reconstructed dose by iterative time reversal is considerably more accurate than the dose reconstructed by back projection. Iterative time reversal imaging has a potential for use in 3D absolute dosimetry.