ESTRO 2022 - Abstract Book

S1615

Abstract book

ESTRO 2022

A retrospective-comparative study where demographic, tumor, treatment and toxicity characteristics of 22 patients treated with BT at 42Gy/7fx and 24 treated with ET at 45-55Gy/9-11fx from June/2020 to June/2021 were collected and analyzed. Table 1. ASTRO indications for radiation therapy in NMSC. Type of treatment Histology Indications

Patients who cannot undergo or decline surgical resection. Patients with tumors in anatomic locations where surgery can compromise function or cosmesis. For groos perineural spread that is clinically or radiologically apparent. Close or positive margins that cannot be corrected with further surgery (secondary to morbidity or adverse cosmetic outcome). In the setting of recurrence after a prior margin- negative resection. Locally advanced or neglected tumors involving bone or infiltrating into muscle. T3 and T4 tumors. For desmoplastic or infiltrative tumors in the setting of chronic immunosuppression.

BCC and SCC

Radical

BCC and SCC

Adjuvant

BCC

SCC

Results Median follow-up was 8 months (range 3-11). 21 patients received treatment with radical intention and 24 as adjuvant. Median age was 77.5 years (57.8% were male). In terms of histology, 53.3% were squamous cell carcinomas and 46.7% basal cell carcinomas. The most frequently treated site was frontoparietal (35.6%). The most frequent collimator diameters used in BT were 45 and 30mm. Of those treated with BT, 66.7% presented acute toxicity (42.9% G-I and 28.6 G-II) and 46.6% chronic toxicity, compared to 100% (62.5% G-I and 33.3% G-II) (p=0.011) and 50% of those treated with ET, respectively. A total of 86.7% obtained excellent aesthetic results with BT and 75% with ET. 100% obtained a complete response at 90 days. There were no recurrences and only one death occurred due to non-tumor causes. Conclusion With equal effectiveness in the treatment of NMSC, BT with Leipzig applicators appears to have better acute toxicity profiles than ET.

Poster (digital): Brachytherapy: Urology (prostate, bladder, penile)

PO-1813 Developing a High-Volume, High-Efficiency CT-Based High Dose Rate Prostate Brachytherapy Workflow

B. Barney 1 , R. Manigold 2 , I. Gordon 1 , M. Cornia 1 , R. Hecox 1

1 Intermountain Healthcare, Radiation Oncology, Salt Lake City, USA; 2 Scripps Health, Radiation Oncology, San Diego, USA

Purpose or Objective To illustrate a robust CT-based single daily fraction, high-dose rate (HDR) brachytherapy (BT) workflow modified over several years to utilize available resources, with a goal of optimizing clinical efficiency and reducing patient procedural time while maintaining quality treatment plans. Materials and Methods An approach of (1) parallel-processing, (2) mitigation of possible errors/uncertainty, and (3) development of tools and ideal setups were utilized to streamline the implantation, treatment planning and treatment delivery processes. Parallel-processing consisted of simultaneous target and avoidance structure definition at a Velocity workstation, BT catheter digitization at an Eclipse workstation, and catheter-transfer tube-afterloader connections, with each process conducted by a capable member of the care team. Concern regarding needle migration was reduced by employing a Diacor Zephyr patient transfer system to safely and quickly transport the patient to the CT table and to the BT vault without displacing BT catheters. Standardized templates for dose prescription, target/normal structure naming, planning optimization, and plan objectives were utilized to accelerate and homogenize the treatment planning process, enabling reproducible plan quality. Physics second checks were facilitated through the creation and implementation of a custom Excel sheet. A free-hand, non-fixed, non-stepper-stabilizer approach was employed by the implanting radiation oncologist/urologist team, allowing for more freedom during the implant and quicker setup/tear down times in the operating room (OR). Results Data for 293 implants treated from 2014-2018 was analyzed. Some implants did not have all data points available, but implants with at least 1 data point were included in the analysis. Times were as follows: 38±8 minutes for implant time, 96±18 minutes from OR start time until planning CT scan completion, 55±15 minutes for treatment planning, 13.5±7 minutes for final treatment preparation, and 187±26 minutes for total procedure time (OR start time until BT catheter removal).