On the Optimization of Bayesian D-Efficient DCE Designs for the Estimation of QALY Tariffs That are Corrected for Nonlinear Time Preferences

Objectives: This article explains how to optimize Bayesian D-efficient discrete choice experiment (DCE) designs for the estimation of quality-adjusted life year (QALY) tariffs that are unconfounded by respondents' time preferences. Methods: The calculation of Bayesian D-errors is explained for DCE designs that allow for the disentanglement of respondents' time and health-state preferences. Time preferences are modelled via an exponential, hyperbolic, or power discount function and the performance of the proposed DCE designs is compared with that of several conventional DCE designs that do not take nonlinear time preferences into account. Results: Based on the achieved D-error, asymptotic standard error, and estimated sample size to obtain statistically significant estimates of the discount rate parameters, the proposed designs outperform the conventional DCE designs. Conclusions: We recommend that applied researchers use appropriately optimized DCE designs for the estimation of QALY tariffs that are corrected for time preferences. The TPC-QALY software package that accompanies this article makes the recommended designs easily accessible for health-state valuation researchers

SPECT/CT-guided lymph drainage mapping for the planning of unilateral elective nodal irradiation in head and neck squamous cell carcinoma

To investigate the feasibility of lymph drainage mapping (LDM) using SPECT/CT to help select head and neck cancer (HNSCC) patients for unilateral elective neck irradiation (ENI). Patients with lateralized HNSCC treated with radiotherapy routinely undergo bilateral ENI, despite the incidence of contralateral regional failure being relatively low even after unilateral ENI. We hypothesized that patients with a lateralized tumor without visible lymph drainage to the contralateral neck have an extremely low risk of contralateral involved nodes. Excluding the contralateral neck from elective irradiation will reduce radiation-induced toxicity and improve quality-of-life.Fifty-five patients with lateralized cT1-3N0-2bM0 HNSCC not crossing the midline underwent LDM. Radiolabeled Tc-99m-nanocolloid was injected in 4-5 depots around and in the primary tumor. Lymph drainage patterns were visualized using planar scintigraphy and SPECT/CT after 4 h. We report on the incidence of contralateral drainage, the location of draining areas, and the size of underlying nodes.Lymphatic drainage was successfully visualized in 54 patients (98%). In 11 patients (20%) with visible contralateral drainage, 14 draining areas (16 nodes; median volume 0.50 cc, diameter 8.0 mm) were identified. Neck levels with contralateral drainage were level II (88%), III (25%), and IV (13%). Contralateral drainage was significantly higher in T3 compared to T1-2 tumors (45 and 14%, respectively, P = 0.035).SPECT/CT-guided LDM is feasible and can be used to guide unilateral ENI in HNSCC patients in prospective studies. In addition, the anatomical confidence in visualization of contralateral drainage indicates a potential for ENI limited to draining levels alone.Biological, physical and clinical aspects of cancer treatment with ionising radiatio

Reduction of GTV to high-risk CTV radiation margin in head and neck squamous cell carcinoma significantly reduced acute and late radiation-related toxicity with comparable outcomes

Background and purpose: We aim to retrospectively investigate whether reducing GTV to high-risk CTV margin will significantly reduce acute and late toxicity without jeopardizing outcome in head-and neck squamous cell carcinoma (HNSCC) treated with definitive (chemo)radiation. Materials and methods: Between April 2015 and April 2019, 155 consecutive patients were treated with GTV to high-risk CTV margin of 10 mm and subsequently another 155 patients with 6 mm margin. The CTV-PTV margin was 3 mm for both groups. All patients were treated with volumetric-modulated arc therapy with daily image-guidance using cone-beam CT. End points of the study were acute and late toxicity and oncologic outcomes. Results: Overall acute grade 3 toxicity was significantly lower in 6 mm, compared to 10 mm group (48% vs. 67%, respectively, p 2 dysphagia (67% vs. 85%, p 0.05, all). Conclusion: The first study reporting on reduction of GTV to high-risk CTV margin from 10 to 6 mm showed significant reduction of the incidence and severity of radiation-related toxicity without reducing local-regional control and survival. (c) 2021 Elsevier B.V. All rights reserved. Radiotherapy and Oncology 162 (2021) 170-177Otorhinolaryngolog