Purpose/Objective(s) In this pilot study, we test the utility of hybrid PET/MRI and circulating biomarkers to non-invasively detect early cardiac inflammatory and functional responses at one month and one year follow-up, simultaneously after radiation therapy (RT) in patients with left-sided breast cancer. Materials/Methods Fifteen left-sided breast cancer patients enrolled in the RICT-BREAST study underwent hybrid PET/MRI cardiac imaging at baseline, 1-month, and 1-year after standard RT. Thirteen patients had scans at baseline, eleven patients had 1-month follow-up scans, while ten patients had scans at 1-year. Overall, eight patients had scans at all timepoints, and ten patients had both 1-month and 1-year follow-up scans. For each scan, a 60-minute list-mode 18FDG/PET scan with prior glucose suppression was acquired. Regional myocardial inflammation was quantified by calculating the percent change of mean18FDG standard uptake (meanSUVbw) at 40-60 minutes post-injection, based on the supplying artery (left anterior descending (LAD), left circumflex or right coronary artery). LV functional matrices were quantified from MR cine images and late gadolinium images acquired simultaneously during PET imaging. Circulating biomarker measurements of high-sensitivity troponin T, C-reactive protein and erythrocyte sedimentation rate were also compared at each timepoint. Results A significant increase of 18FDG/PET myocardial uptake (meanSUVbw) in LAD segments (p = 0.04, 0.14, 10%.) was detected at 1-month follow-up in 8 of 11 patients up. However, in only 5 of 10 patients increased uptake was observed in LAD segments at 1-year follow-up compared to 1-month (mean of 0.1) and 4 of 8 had an increase at 1-year compared to baseline (mean increase of 0.2). However, it was insignificant (p ≥ 0.96). A significant reduction of LV stroke volume (p < 0.03, < -7%) was identified both at 1-month and 1-year follow-up. No significant changes in any biomarkers were seen at both follow-up timepoints. No abnormal enhancement from late gadolinium MR images was observed across patients at 1-year timepoint. Conclusion 18FDG/PET-MRI can simultaneously detect cardiac inflammation, functional response changes, and LV stroke volume changes in left-sided breast cancer patients as early as 1-month post radiotherapy, which, in some patients, persists out to one year. Clinical outcomes must be tracked to determine the predictive value of these biomarkers.

Phyllodes tumor (PT) is a rare fibroepithelial breast neoplasm that is typically graded histopathologically as benign, borderline, and malignant. Malignant PTs (MPTs) exhibit marked stromal cellularity, atypia, overgrowth, increased mitotic activity, and the propensity to metastasize. MPTs represent 10%-15% of all PT cases and often have a notably aggressive disease course. Infrequently, these tumors contain heterologous histological elements, including liposarcoma and fibrosarcoma, among others. Rhabdomyosarcomatous differentiation is an exceptionally rare example of such variation. This report documents the clinical presentation and disease course of a 62-year-old woman diagnosed with MPT with rhabdomyosarcomatous differentiation, just the seventh such confirmed case in the English literature. The patient experienced an arduous disease course, developing metastases to her lungs and axial skeleton just months after her initial diagnosis. Palliative radiation and chemotherapy were initiated, but the patient unfortunately succumbed to her disease just 10 months after the initial diagnosis. This case adds to the scarce literature surrounding the rare development of a heterologous rhabdomyosarcomatous element in an MPT, as well as the decisionmaking process surrounding the use of radiation to treat such lesions. The details discussed in this paper may inform future approaches for patients diagnosed with this disease.

Visual Abstract Our purpose was to investigate the utility of 18F-FDG PET/MRI and serial blood work to detect early inflammatory responses and cardiac functionality changes at 1 mo after radiation therapy (RT) in patients with left-sided breast cancer. Methods: Fifteen left-sided breast cancer patients who enrolled in the RICT-BREAST study underwent cardiac PET/MRI at baseline and 1 mo after standard RT. Eleven patients received deep-inspiration breath-hold RT, whereas the others received free-breathing RT. A list-mode 18F-FDG PET scan with glucose suppression was acquired. Myocardial inflammation was quantified by the change in 18F-FDG SUVmean (based on body weight) and analyzed on the basis of the myocardial tissue associated with the left anterior descending, left circumflex, or right coronary artery territories. MRI assessments, including left ventricular functional and extracellular volumes (ECVs), were extracted from T1 (before and during a constant infusion of gadolinium) and cine images, respectively, acquired simultaneously during the PET acquisition. Cardiac injury and inflammation biomarker measurements of high-sensitivity troponin T, high-sensitivity C-reactive protein, and erythrocyte sedimentation rate were measured at the 1-mo follow-up and compared with preirradiation values. Results: At the 1-mo follow-up, a significant increase (10%) in myocardial SUVmean in left anterior descending segments (P = 0.04) and ECVs in slices at the apex (6%) and base (5%) was detected (P ≤ 0.02). Further, a significant reduction in left ventricular stroke volume (−7%) was seen (P < 0.02). No significant changes in any circulating biomarkers were seen at follow-up. Conclusion: Myocardial 18F-FDG uptake and functional MRI, including stroke volume and ECVs, were sensitive to changes at 1 mo after breast cancer RT, with findings suggesting an acute cardiac inflammatory response to RT.

Palliative radiotherapy (PRT) is an effective treatment for managing symptoms of advanced cancer. At least half of all radiation treatments are delivered with palliative intent, aimed at relieving symptoms, such as pain or shortness of breath. Symptomatic patients must receive PRT quickly, therefore expeditious treatment planning is essential. Standard radiation planning requires a dedicated CT scan acquired at the cancer centre, called a ‘CT simulation’, which facilitates treatment planning (i.e. tumor delineation, placement of radiation beams and dose calculation). However, the CT simulation process creates a bottleneck and often leads to delays in starting treatment. Other researchers have indicated that CT simulation can be replaced by the use of standard diagnostic CT scans for target delineation and planning, which are normally acquired through the radiology department as part of standard patient workup. The goals of this feasibility study are to assess the efficacy, acceptability and scalability of diagnostic-CT-enabled planning, compared to conventional CT simulation planning, for patients receiving PRT to bone, soft tissue and lung disease. This is a randomized, phase II study, with 33 PRT patients to be randomized in a 1:2 ratio between conventional CT simulation (Arm 1), and the diagnostic CT enabled planning workflow (Arm 2). Patients will be stratified by treatment target volume (bone and soft tissue metastasis vs. primary or metastatic intrathoracic disease targets). The primary endpoint is the amount of time the patient spends at the cancer centre. Secondary endpoints include efficacy (rate of plan deliverability and rate of plan acceptability on blinded dose distribution review), stakeholder acceptability (based on patient and clinician perception of acceptability questionnaires) and scalability. This study will investigate the efficacy, acceptability and scalability of a “sim-free” PRT pathway compared to conventional CT simulation. The workflow may provide opportunity for resource optimization by using pre-existing diagnostic imaging and requires minimal investment due to its similarity to current PRT models. It also offers potential benefit to patients by eliminating an imaging procedure, reducing the amount of time spent at the cancer centre, and expediting time to treatment. Clinicaltrials.gov identifier: NCT05233904. Date of registration: February 10, 2022; current version: 1.4 on April 29, 2022.

Abstract Purpose: To investigate the utility of hybrid 18FDG-PET/MRI and serial blood work to detect early inflammatory response and cardiac functionality changes at one-month post-radiation therapy (RT) in patients with left-sided breast cancer.Methods: Fifteen left-sided breast cancer patients enrolled in the RICT-BREAST study underwent hybrid PET/MRI cardiac imaging at baseline and one-month after standard RT. Eleven patients received deep-inspiration breath-hold RT, while others received free-breathing RT. A list-mode 18FDG/PET scan with glucose suppression was acquired. Myocardial inflammation was quantified by the change of mean 18FDG standard uptake and analyzed based on the coronary vascular territory (left anterior descending (LAD), left circumflex or right coronary artery).MR assessments, including LV functional and extracellular volume matrices (ECV), were extracted from T1 (pre and during-constant infusion of gadolinium) and cine images, respectively, acquired simultaneously during PET acquisition. Cardiac injury and inflammation biomarker measurements of hs-TnT, hs-CRP and erythrocyte sedimentation rate were compared at the 1-month follow-up in this study.Results: At one-month follow-up, a significant increase (10%) of 18FDG/PET myocardial uptake (meanSUVbw) in LAD segments (p=0.04) and ECV in slices at the apex (6%) and base (5%) were detected (p≤0.02). Further, a significant reduction of LV stroke volume (-7%) was seen (p <0.02). No significant changes in all circulating biomarkers at follow-up were shown. Conclusions: 18FDG/PET myocardial uptake and functional MR, including SV and ECV were sensitive to changes at one-month after breast cancer RT with findings suggesting an acute cardiac inflammatory response which is an important cardiotoxicity surrogate to RT. The clinical pilot study (NCT03748030, November 16, 2018) was approved by the Western University Human Research Ethics Board (HSREB ID 112991), funded by Lawson Strategic Research Fund (R19-292).

BACKGROUND:Adjuvant whole-breast radiotherapy (RT) is a significant part of the standard of care treatment after breast cancer (BC) conserving surgery. Modern techniques including intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) have constituted to better target coverage and critical organs sparing. However, BC survivors are at risk of developing radiation-induced cardiac toxicity. Hence, deep-inspiration breath-hold (DIBH) techniques have been implemented at many centers to further reduce cardiac exposure but require compliance. 4D-CT robust optimization can account for heart intrafractional motion per breathing phase. The optimization has been explored in cardiac sparing of breast IMRT compared to DIBH in a small sample size but has not been evaluated in substructures sparing, nor in VMAT. To provide patients who are not compliant to breath-hold with an optimal treatment approach, various heart sparing techniques need to be evaluated for statistical significance and clinical feasibility. AIM:This retrospective study aimed to provide an extensive dosimetric heart sparing comparison of free-breathing, 4D-CT-based treatment planning, including robust optimization with DIBH-based treatment planning. Combinations of forward and inverse IMRT and VMAT are also considered. METHODS:Fifteen early stage left-sided BC standard treatment plans were selected. Breast, lung, left anterior descending artery (LAD), left ventricle (LV), and the whole heart were contoured on each 4D-CT phase and DIBH CT dataset. Each treatment plan was optimized using forward/inverse IMRT and VMAT on the following CT datasets: DIBH, average 4D-CT, and the complete 4D-CT dataset needed for robust optimization. Dose-volume histograms were used to compare V5GyHeart, mean heart dose, mean and max LAD dose, mean LV dose, and V50%Lung. RESULTS:All RT techniques assessed including 4D robust optimization were clinically feasible. Statistically significant differences in mean heart, LAD and LV dose, max LAD dose, and V5GyHeart (p < 0.01) but no difference in V50%Lung (p = 0.29) were found between different techniques. IMRT DIBH achieved the optimal cardiac and substructure sparing among treatment plans. 4D robust IMRT had significantly greater mean heart and LV dose than DIBH IMRT (p ≤ 0.01), except LAD dose. Among free-breathing methods, no difference in all cardiac and substructure dose parameters was observed (p > 0.2) in comparing forward and inverse IMRT with average 4D-CT, inverse average 4D-CT, and 4D robust with IMRT, and between average 4D-CT VMAT and 4D robust VMAT. Only V5GyHeart and mean LV dose were significantly greater in 4D robust VMAT (p < 0.01) compared to DIBH VMAT. Mean heart and LV doses were significantly reduced (p < 0.01) in DIBH IMRT compared to DIBH VMAT. Moreover, mean heart and LV dose, V5GyHeart were significantly reduced in inverse IMRT average 4D-CT compared to average 4D-CT VMAT (p < 0.02) and in 4D robust IMRT compared to 4D robust VMAT (p < 0.04). CONCLUSION:This study demonstrated the clinical feasibility of 4D robust optimization in limiting the cardiac and substructures dose during free-breathing RT with both IMRT/VMAT for patients who are not compliant with breath-hold RT. However, this study also presents that 4D robust optimization can reduce LAD dose but not fully outperform DIBH or conventional 4D-CT-based planning with IMRT/VMAT in heart sparing in treating early staged left-sided BC patients.

e17052 Background: Men with localized prostate cancer have many options for initial definitive treatment. In 2015, Cancer Care Ontario Quality Based Procedures (QBP) recommended that men undergoing radical prostatectomy (RP) in Ontario be seen by a radiation oncologist (RO) or discussed at a multidisciplinary case conference (MCC) prior to surgery. An a-priori target rate of 76% was set by QBP, but to our knowledge, has not been reported upon to date. Our objective was to use population-based data to explore factors associated with not receiving RO consult/MCC prior to RP. Methods: Men with localized prostate cancer diagnosed and treated in Ontario, Canada with RP between 2007 and 2017 were identified using administrative data from the Institute for Clinical Evaluative Sciences. Physician billing data was utilized to identify patients who received RO consult/MCC prior to RP. Trends were evaluated using the Cochran-Armitage test. Multivariable logistic regression was used to identify patient and provider factors predictive of RO/MCC prior to RP. Results: 31,467 men with localized prostate cancer underwent RP between 2007 and 2017. Prior to RP, 29.3% of men were seen by RO, 1.0% underwent MCC, and 1.6% had both. RO consult/MCC prior to RP increased from 18.0% in 2007 to 47.8% in 2017 ( p<0.001). On multivariable analysis, the Odds Ratio (OR) of RO consult/MCC prior to RP between the lowest and highest geographic regions (LHINs) was 8.79 (95% CI 6.83–11.32, p<0.001). RO consult/MCC was less likely to occur for patients living further from the nearest cancer center (OR 0.74 per 50km, 95% CI 0.70–0.77, p<0.001) and more likely to occur for men residing in the highest versus lowest income quintile regions (OR 1.42, 95% CI 1.30–1.55, p<0.001). Men with NCCN Low (OR 1.31, 95% CI 1.16–1.47, p<0.001), High (OR 1.20, 95% CI 1.09–1.31, p<0.001) or Very High (OR 1.24, 95% CI 1.11–1.30, p<0.001) risk disease were more likely to receive RO consult/MCC compared to those with favourable-intermediate risk disease. Of the 128 urologists who performed at least 10 RP between 2016 and 2017, RO referral/MCC rate ranged from 0% to 100%, with 31 urologists (24.2%) having ≥76% of their patients seen prior to RP. To meet QBP targets in 2017, an additional 701 men would have needed RO consult/MCC. If all were seen by RO, approximately 2.4 additional full time equivalent RO positions would be needed. Conclusions: Despite increasing rates of utilization, a large proportion of men are not seen by RO or MCC prior to RP in Ontario, Canada. While the largest factors predicting RO consult/MCC discussion appear to be geographic and which urologist performs the RP, these factors are closely intertwined. In addition, these factors may be related to RO availability and radiation system capacity, which would need to be addressed to meet patient demand should QBP consultation rates be mandated to reduce disparities in pre-RP consultation practices.

Early-stage breast cancer patients comprise a large proportion of patients treated with radiotherapy in Canada. Proponents have suggested that five-fraction hypofractionated radiotherapy for these patients would result in significant cost savings. An assessment of this argument is thus warranted. The FAST-Forward and UK FAST clinical trials each demonstrated that their respective hypofractionated regimens provided equivalent outcomes compared with standard regimens. Thus, a cost-minimization analysis was performed to quantify the potential savings associated with these regimens, which were designated as FAST-Forward 1 (26 Gy/5 fractions/1 week) and FAST-Forward 2 (27 Gy/5 fractions/1 week), and UK FAST 1 (28.5 Gy/5 fractions/5 weeks) and UK FAST 2 (30 Gy/5 fractions/5 weeks). A standard regimen of 42.5 Gy/16 fractions/5 weeks was also included. A comprehensive model of radiotherapy costs for a Canadian cancer centre was created. Time, labour costs, and capital costs were calculated for each regimen and applied using established measures. The total costs per patient for the FAST-Forward trials were $851.77 for FAST-Forward 1 and $874.77 for FAST-Forward 2, providing a total savings of $487.99 and $464.99, respectively. Similarly, the total costs per patient for the FAST trials were $979.75 for UK FAST 1 and $1017.70 for UK FAST 2, providing savings of $360.01 and $322.06, respectively. Following the FAST-Forward 1 regimen results in the greatest reduction of infrastructure and human resources costs at 36.42% compared with the standard. Sensitivity analysis shows a maximum per-patient costs savings ranging from $474.60 to $508.53 for the FAST-Forward 1 trial, which translates to an annual savings of $174,700/year locally and $2.06 million/year province-wide, based on a moderate-to-large size department workload. Compared with a standard radiotherapy regimen, all FAST-Forward and UK FAST hypofractionated regimens provide cost savings for the treatment of early-stage breast cancer. The cost savings associated with each of these equivalent regimens can be directly calculated; activities in this model can easily be adjusted to account for cost variations, allowing other centres to calculate cost impacts specific to their own centres.

Importance Men and women should earn equal pay for equal work. An examination of the magnitude of pay disparities could inform strategies for remediation. Objective To examine gender-based differences in pay within a large, comprehensive physician population practicing within a variety of payment systems. Design, Setting, and Participants This cross-sectional study used data from the Ontario Health Insurance Plan (OHIP) in the 2017 to 2018 fiscal year to estimate differences in gross payments between men and women physicians in Ontario, Canada. Pay gaps were calculated annually and daily. Regression analyses were used to control for observable practice characteristics that could account for individual differences in daily pay. In Canada's largest province, Ontario, medical services are predominantly provided by self-employed physicians who bill the province's single payer, OHIP. All physicians who submitted claims to OHIP were included. Data were analyzed from January 2020 to July 2021. Exposures Physician gender, obtained from the OHIP Corporate Provider Database. Gender is recorded as male or female. Main Outcomes and Measures Gross clinical payments were tabulated for individual physicians on a daily and annual basis in conjunction with each physician's practice characteristics, setting, and specialty. Results A total of 31 481 physicians were included in the study sample (12 604 [40.0%] women; 18 877 [60.0%] men; mean [SD] time since graduation, 23.3 [13.6] years), representing 99% of active physicians in Ontario. The unadjusted differences in clinical payments between male and female physicians were 32.8% (95% CI, 30.8%-34.6%) annually and 22.5% (95% CI, 21.2%-23.8%) daily. After accounting for practice characteristics, region, and specialty, the overall daily payment gap was 13.5% (95% CI, 12.3%-14.8%). The pay gap persisted with differing magnitudes when examined by specialty (ranging from 6.6% to 37.6%), practice setting (8.3% to 17.2%), payment model (13.4% to 22.8% for family medicine; 8.0% to 11.6% for other specialties), and rurality (8.0% to 16.5%). Conclusions and Relevance This cross-sectional study examined differences in magnitude of annual and daily payment gaps and between unadjusted and adjusted gaps. Comparing the gaps for different specialties, geography, and payment systems illustrated the complexity of the issue by showing that the pay gap varied for physicians in different practice settings. As such, multiple directed interventions will be necessary to ensure that all physicians are paid equally for equal work, regardless of gender.

The need to minimize in-person interactions during the COVID-19 pandemic has led to fewer clinical learning opportunities for trainees. With ongoing utilization of virtual platforms for resident education, efforts to maximize their value are essential. Herein we describe a resident-led quality improvement initiative to optimize remote contouring and virtual contour review. From April to June 2020, radiation oncology (RO) residents at our institution were assigned modified duties. We implemented a program to source and assign cases to residents for remote contouring and to promote and optimize virtual contour review. Resident-perceived educational value was prospectively collected and analyzed. All nine RO residents at our institution (PGY1–5) participated, and 97 cases were contoured during the evaluation period. Introduction of the Remote Contouring and Virtual Review (RECOVR) program coincided with a significant increase in mean cases contoured per week, from 5.5 to 17.3 (p = 0.015), and an increased proportion of cases receiving virtual review, from 14.8% to 58.6% (p < 0.001). Residents reported that the value of immediate feedback during virtual review was similar to that of in-person review (4.6 ± 0.1 vs. 4.5 ± 0.2, p = 0.803) and significantly higher than feedback received post hoc (e.g., email; 3.6 ± 0.2, p < 0.001). The implementation of a remote process for contour review led to significant increases in contouring, and virtual contour review was rated as highly as in-person interactions. Our findings provide a data-driven rationale and framework for integrating remote contouring and virtual review into competency-based medical education.

Purpose: We develop a multi-centric response predictive model using QUS spectral parametric imaging and novel texture-derivate methods for determining tumour responses to neoadjuvant chemotherapy (NAC) prior to therapy initiation. Materials and Methods: QUS Spectroscopy provided parametric images of mid-band-fit (MBF), spectral-slope (SS), spectral-intercept (SI), average-scatterer-diameter (ASD), and average-acoustic-concentration (AAC) in 78 patients with locally advanced breast cancer (LABC) undergoing NAC. Ultrasound radiofrequency data were collected from Sunnybrook Health Sciences Center (SHSC), University of Texas MD Anderson Cancer Center (MD-ACC), and St. Michaels Hospital (SMH) using two different systems. Texture analysis was used to quantify heterogeneities of QUS parametric images. Further, a second-pass texture analysis was applied to obtain texture-derivate features. QUS, texture- and texture-derivate parameters were determined from both tumour core and a 5-mm tumour margin and were used in comparison to histopathological analysis for developing a response predictive model to classify responders versus non-responders. Model performance was assessed using leave-one-out cross-validation. Three standard classification algorithms including a linear discriminant analysis (LDA), k-nearest-neighbors (KNN), and support vector machines-radial basis function (SVM-RBF) were evaluated. Results: A combination of tumour core and margin classification resulted in a peak response prediction performance of 88% sensitivity, 78% specificity, 84% accuracy, 0.86 AUC, 84% PPV, and 83% NPV, achieved using the SVM-RBF classification algorithm. Other parameters and classifiers performed less well running from 66% to 80% accuracy. Conclusions: A QUS-based framework and novel texture-derivative method enabled accurate prediction of responses to NAC. Multi-centric response predictive model provides indications of the robustness of the approach to variations due to different ultrasound systems and acquisition parameters.

As the coronavirus disease 2019 (COVID-19) pandemic continues to disrupt nearly all facets of daily life, residency programs must ensure the safety and wellness of their residents while maintaining a commitment to their training and advancement. In addition to standard clinical training, radiation oncology residency programs integrate highly specialized elements specific to the delivery of radiation therapy. Few publications have addressed the significant effects of the pandemic on medical training and even fewer have addressed concerns specific to radiation oncology. We report our experience developing a resident-led adaptation of our training program in response to the COVID-19 pandemic with the aim of assisting other programs to meet this challenge.

Background and purpose: Declining prostate brachytherapy utilization has been reported in several studies, despite strong evidence for efficacy and safety compared to alternatives. We sought to evaluate contemporary trends in brachytherapy, external beam radiotherapy (EBRT) and prostatectomy utilization in a publicly funded healthcare system. Materials and methods: Men with localized prostate cancer diagnosed and treated between 2006 and 2017 in Ontario, Canada were identified using administrative data. Men received EBRT, brachytherapy (monotherapy or boost) or prostatectomy as initial definitive management. Multivariable logistic regression evaluated patient-, tumour-, and provider-factors on treatment utilization. Results: 61,288 men were included. On multivariable regression, the odds of receiving brachytherapy boost increased 24% per year (odds ratio [OR]:1.24, 95% CI 1.22-1.26, p < 0.01), brachytherapy monotherapy increased 3% per year (OR:1.03, 95% CI:1.02-1.04, p < 0.01), and prostatectomy declined by 6% per year (OR:0.94, 95% CI 0.93-0.95, p < 0.01). Treatment year was not significant on multivariable modelling of EBRT. In a separate multivariable model limited to those who received radiotherapy, if the first radiation oncologist seen performed brachytherapy, the OR of receiving brachytherapy monotherapy over EBRT was 5.66 (95% CI: 5.11-6.26, p < 0.01) and 2.88 (95% CI: 2.60-3.19, p < 0.01) for brachytherapy boost over EBRT alone. Substantial geographic, provider and patient variation in treatment receipt was observed. Conclusion: We found increasing brachytherapy utilization, largely driven by increasing utilization of brachytherapy boost. To our knowledge, this is the first report of increasing brachytherapy use in the era of dose escalated EBRT. (C) 2020 Published by Elsevier B.V.

Background:Cigarette smoking is carcinogenic and has been linked to inferior treatment outcomes and complication rates in cancer patients. Here, we report the results of an 18-month pilot smoking cessation program that provided free nicotine replacement therapy (nrt). Methods:In January 2017, the smoking cessation program at our institution began offering free nrt for actively cigarette-smoking patients with cancer. The cost of 4 weeks of nrt was covered by the program, and follow-up was provided by smoking cessation champions. Results:From January 2017 to June 2018, 8095 patients with cancer were screened for cigarette use, of whom 1135 self-identified as current or recent smokers. Of those 1135 patients, 117 enrolled in the program and accepted a prescription for nrt. The rates of patient referral and patients attending a referral appointment were significantly higher in 2018-2018 than they had been in 2015-2016 (100% vs. 80.3%, p < 0.001, and 27.6% vs. 11.3%, p < 0.001, respectively). Median follow-up was 9.0 months (25%-75% interquartile range: 5.7-11.6 months). Of the patients who accepted nrt and who also had complete data (n = 71), 25 (35.2%) reported complete smoking cessation, and 32 (45.1%) reported only decreased cigarette smoking. On univariable analysis, no factors were significantly predictive of smoking cessation, although initial cigarette use (>10 vs. ≤10 initial cigarettes) was significantly predictive of smoking reduction (odds ratio: 5.04; 95% confidence interval: 1.46 to 17.45; p = 0.011). Conclusions:This pilot study of free nrt demonstrated rates of referral and acceptance of nrt that were improved compared with historical rates, and most referred patients either decreased their use of cigarettes or quit entirely.

e17608 Background: A worldwide decline in prostate brachytherapy (BT) utilization has been reported in multiple health care settings/jurisdictions, despite strong evidence for efficacy and safety compared to other alternatives. We sought to evaluate contemporary trends in BT, EBRT and prostatectomy utilization in a publicly funded healthcare system. Methods: Men with localized prostate cancer diagnosed and treated between 2007 and 2017 in Ontario, Canada were identified using administrative data from the Institute for Clinical Evaluative Sciences. Men were coded to have received EBRT, BT (monotherapy or boost) or prostatectomy as initial definitive management. Trends were evaluated using the Cochran-Armitage test. Multivariate logistic regression was used to evaluate patient-, tumour-, and provider-factors on treatment utilization over time. Results: 57,655 men were included in our study. Prostate BT use increased from 7.5% of all treatments in 2007 to 15.4% in 2017 ( p< 0.01), primarily due to increased use of BT boost (1.7% in 2007 to 10.4% in 2017, p < 0.01). Relative to EBRT, BT use increased from 17.9% in 2007 to 28.1% in 2017 ( p< 0.01). On multivariate analysis (MVA), BT boost use increased by 28% per year (OR 1.28, 95% CI 1.26–1.31, p< 0.01) and BT monotherapy use increased by 12% per year (OR 1.12, 95% CI 1.10–1.14, p< 0.01), offset by decreasing prostatectomy use (12% per year, OR 0.88, 95% CI 0.87–0.89, p< 0.01). Comparing BT to EBRT, the strongest predictors of receiving BT were geographic residence (OR 27.6, 95% CI: 20.3–37.6, p< 0.01 between highest/lowest Local Health Integration Networks) and whether the first consulting radiation oncologist performed BT (OR 3.46, 95% CI: 3.15–3.80, p< 0.01). Other significant factors predicting BT use vs. EBRT included lower age, lower PSA, lower Charlson comorbidity score and increasing neighborhood income quintile. Low-intermediate, high-intermediate and high-risk groups were predictive of receiving BT boost, whereas BT monotherapy was predominantly used in low-risk disease. Conclusions: Contrary to trends observed in other jurisdictions, utilization of prostate BT is increasing over time in Ontario. However, substantial variation in BT utilization was found, strongly driven by both geographic region and radiation oncologist BT practice patterns. To our knowledge, this is the first study to report increasing BT utilization in the era of dose-escalated EBRT, with Ontario potentially serving as a model to promote BT utilization elsewhere.