Cancer Care South East

Locally advanced rectal cancer is often treated with multimodal therapy. Patients may receive care at a single institution or across multiple institutions. We designed this population-level retrospective cohort to determine the association between fragmented care and timeliness of treatment and long-term oncologic outcomes. Patients with stage II/III rectal cancer who received at least two treatment modalities between 2010 and 2019 in Ontario, Canada were included. Fragmented care was defined as receiving at least one treatment modality at two or more institutions, while nonfragmented care was defined as receiving all treatments at a single institution. The primary outcome was timeliness of treatment as defined by Cancer Care Ontario Recommendations. Secondary outcomes included overall survival (OS). Overall, 3381 patients received fragmented care and 2026 patients received nonfragmented care. Patients receiving nonfragmented care were more likely to undergo timely initiation of treatment (OR: 1.72, 95% CI: 1.50-1.97, p < 0.0001). This was driven by timely initiation of chemotherapy (OR: 1.32, 95% CI: 1.16-1.49, p < 0.0001). There was little to no difference in OS (HR: 1.11, 95% CI: 0.95-1.30, p = 0.19). Patients with stage II/III rectal cancer receiving multimodal therapy may experience less timely initiation of treatment if their cancer care is fragmented. This did not translate into differences in long-term oncologic outcomes.

Protracted times to diagnosis of cancer can lead to increased patient anxiety, and in some cases, disease progression and worse outcomes. This study assessed the time to diagnosis for melanoma, and its variability, according to patient-, disease-, and system-level factors. This is a descriptive, cross-sectional study in Ontario, Canada from 2007-2019. We used administrative health data to measure the diagnostic interval (DI)-and its two subintervals-the primary care subinterval (PCI) and specialist care subinterval (SCI). Multivariable quantile regression was used. There were 33,371 melanoma patients. The median DI was 36 days (interquartile range [IQR]: 8-85 days), median PCI 22 days (IQR: 6-54 days), and median SCI 6 days (IQR: 1-42 days). Increasing comorbidity was associated with increasing DI. Residents in the most deprived neighbourhoods and those in rural areas experienced shorter DIs and PCIs, but no differences in SCI. There was substantial variation in the DI and SCI across health regions, but limited differences in the PCI. Finally, patients with a history of non-melanoma skin cancer, and those previously established with a dermatologist experienced significantly longer DI, PCI, and SCI. This study found variability in the melanoma DI, notably by system-level factors.

Globally, the rising cost of anticancer therapy has motivated efforts to quantify the overall value of new cancer treatments. Multicriteria decision analysis offers a novel approach to incorporate multiple criteria and perspectives into value assessment. The authors recruited a diverse, multistakeholder group who identified and weighted key criteria to establish the drug assessment framework (DAF). Construct validity assessed the degree to which DAF scores were associated with past pan-Canadian Oncology Drug Review (pCODR) funding recommendations and European Society for Medical Oncology Magnitude of Clinical Benefit Scale (ESMO-MCBS; version 1.1) scores. The final DAF included 10 criteria: overall survival, progression-free survival, response rate, quality of life, toxicity, unmet need, equity, feasibility, disease severity, and caregiver well-being. The first 5 clinical benefit criteria represent approximately 64% of the total weight. DAF scores ranged from 0 to 300, reflecting both the expected impact of the drug and the quality of supporting evidence. When the DAF was applied to the last 60 drugs (with reviewers blinded) reviewed by pCODR (2015-2018), those drugs with positive pCODR funding recommendations were found to have higher DAF scores compared with drugs not recommended (103 vs 63; Student t test P=.0007). DAF clinical benefit criteria mildly correlated with ESMO-MCBS scores (correlation coefficient, 0.33; 95% CI, 0.009-0.59). Sensitivity analyses that varied the criteria scores did not change the results. Using a structured and explicit approach, a criterion-based valuation framework was designed to provide a transparent and consistent method with which to value and prioritize cancer drugs to facilitate the delivery of affordable cancer care.

Reason for withdrawal from publication A systematic review using individual participant data has recently been conducted by the Early Breast Cancer Trialists’ Collaborative Group. This represents a very high-quality review of the evidence and a Cochrane Review on the same topic would not significantly add to the knowledge base. Therefore, we direct readers to the systematic review published in The Lancet (2015, volume 386, pages 1341-1352).

Designed experiments were performed to produce empirical models for the dose sensitivity, initial absorbance, and dose-rate dependence respectively for leucocrystal violet (LCV) micelle gel dosimeters containing cetyltrimethylammonium bromide (CTAB) and 2,2,2-trichloroethanol (TCE). Previous gels of this type showed dose-rate dependent behaviour, producing an ∼18% increase in dose sensitivity between dose rates of 100 and 600 cGy min-1. Our models predict that the dose rate dependence can be reduced by increasing the concentration of TCE, CTAB and LCV. Increasing concentrations of LCV and CTAB produces a significant increase in dose sensitivity with a corresponding increase in initial absorbance. An optimization procedure was used to determine a nearly dose-rate independent gel which maintained high sensitivity and low initial absorbance. This gel which contains 33 mM CTAB, 1.25 mM LCV, and 96 mM TCE in 25 mM trichloroacetic acid and 4 wt% gelatin showed an increase in dose sensitivity of only 4% between dose rates of 100 and 600 cGy min-1, and provides an 80% greater dose sensitivity compared to Jordan’s standard gels with similar initial absorbance.

Full three‐dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging.In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data in an irradiated volume can help understand interplay effects during TomoTherapy or VMAT. Titania Juang: Special techniques in the clinic and research Understand the potential for 3D dosimetry in validating dose accumulation in deformable systems, and Observe the benefits of high resolution measurements for precision therapy in SRS and in MicroSBRT for small animal irradiators Geoffrey S. Ibbott: 3D Dosimetry in end‐to‐end dosimetry QA Understand the potential for 3D dosimetry for end‐to‐end radiation therapy process validation in the in‐house and external credentialing setting.Canadian Institutes of Health Research; L. Schreiner, Modus QA, London, ON, Canada; T. Juang, NIH R01CA100835

Radiochromic leuco crystal violet (LCV) micelle gel dosimeters are promising three-dimensional radiation dosimeters because of their spatial stability and suitability for optical readout. The effects of surfactant type and surfactant concentration on dose sensitivity of LCV micelle gels are tested, demonstrating that dose sensitivity and initial colour of the gel increases with increasing Triton x-100 (Tx100) concentration. Using Cetyl Trimethyl Ammonium Bromide (CTAB) in place of Tx100 produces gels that are nearly colourless prior to irradiation, but reduces the dose sensitivity. The separate effects of Tri-chloro acetic acid concentration and pH are investigated, revealing that controlling the pH near 3.6 is crucial for achieving high dose sensitivity. The sensitizing effect of chlorinated species on dose sensitivity is tested using 2,2,2-trichloroethanol (TCE), chloroform, and 1,1,1-trichloro-2-methyl-2-propanol hemihydrate. TCE gives the largest improvement in dose sensitivity and is recommended for use in micelle gel dosimeters because it is less volatile and safer to use than chloroform. Preliminary experiments on a new gel containing CTAB as the surfactant and TCE show that this new gel gives a dose sensitivity that is 24% higher than that of previous LCV micelle gels and is nearly colourless prior to irradiation.

This paper reports on a survey of medical physicists who write and use in‐house written software as part of their professional work. The goal of the survey was to assess the extent of in‐house software usage and the desire or need for related software quality guidelines. The survey contained eight multiple‐choice questions, a ranking question, and seven free text questions. The survey was sent to medical physicists associated with cancer centers across Canada. The respondents to the survey expressed interest in having guidelines to help them in their software‐related work, but also demonstrated extensive skills in the area of testing, safety, and communication. These existing skills form a basis for medical physicists to establish a set of software quality guidelines.PACS number: 87.55.Qr