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Session Item

Tuesday

August 31

11:00 - 12:15

N105-N106

Recent developments in the treatment of rectal cancer

Chair: Sebastian Meltzer, Norway;

Chair: , Italy

Overview: Preoperative chemoradiation therapy is an integral part of the treatment of advanced rectal cancer. Intensification strategies in the neoadjuvant setting are debated, with improved local control at the cost of increasing toxicity. This session will provide an overview of dose-intensification trials, and what is needed to obtain a complete response. Further, the hype and pitfalls of radiosensitation and concomitant chemotherapy, as well as the total neoadjuvant treatment strategy will be discussed. Updated results from the RAPIDO trial will be presented. Lastly, patient selection to organ preservation strategies will be debated, with prediction models of complete response in the interface between research and clinic.

Session Type: Symposium

Track: Clinical

Journey:

Initial dosimetric experience using daily AI-assisted adaptive radiotherapy for laryngeal cancer

Noam Weizman, Israel

Presentation Number: PO-1567

Abstract

Abstract Title:

Initial dosimetric experience using daily AI-assisted adaptive radiotherapy for laryngeal cancer

Authors:

Noam Weizman¹, Philip Blumenfeld¹, Marc Wygoda¹, Isaac Darrs¹, Amichay Meirovitz¹, Janna Menhel¹, Jon Feldman¹, Aron Popovtzer¹

¹Hadassah medical center, Radiation department, Jerusalem, Israel

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Purpose or Objective

Adaptive radiation therapy (ART) provides a method to modify the radiation treatment plan secondary to structural and spatial changes that occur during a treatment course. Specifically, ART is relevant in head and neck cancers as many patients will experience changes of the target volumes and organs-at-risk (OARs) during treatment due to combination of treatment response, weight loss, inflammation and effects on normal tissues. Our institution recently began performing daily ART for select cases of locally advanced larynx cancers using a commercially available, online adaptive platform (ETHOS Varian) with AI-assisted workflows on daily cone-beam computed tomography (CBCT). Herein we report our initial dosimetric experience using this novel technique for laryngeal cancers.

Material and Methods

All patients were presented in the weekly physician conference. Patients potentially benefiting from daily adaptation underwent CT-simulation and were planned on the AI system. A total of three patients being treated (105 radiotherapy sessions/plans) were imaged using kV-CBCT prior to treatment. Subsequent workflow included: 1) patients’ set up, positioning and image approval, 2) AI-based auto-contour and structure deformation of OARs and Targets on CBCT, 3) editing of contours by treating physician, 4) two plans are generated, a CT sim-based plan with deformed structures(scheduled) and a re-optimized structures deformed plan (adaptive), 5) plans evaluation and approval of best option, 6) plan QA and 7) plan delivery. Data was collected using Ethos TPS and statistical analysis comparing the scheduled versus adaptive plans was performed using STATA 13.0.

Results

105 adaptive and scheduled radiotherapy plans were generated of which 78 adaptive were delivered. Average daily change in PTV size was: 1.5 cc (95% CI: -0.9cc - -2.0cc, p<.001). In all cases, cumulative adaptive plans demonstrated superior PTV coverage by 1.1% (95% CI: 0.6%-1.5%, p<.001) and a reduction in maximum dose by -2.4% (95% CI: -1.9%- -2.8%, p<.001). High priority OARs demonstrated a reduction in mean dose for the laryngeal constrictors by 2.2Gy ± 0.1Gy, submandibular gland right and left, 2 Gy ± 0.1Gy and 2.5 Gy ± 0.1Gy respectively.

Conclusion

AI-assisted adaptive radiation therapy for larynx cancer is feasible and may potentially improve the therapeutic index for different tumor types. Prospective clinical evaluation is indicated to further this novel approach.