Main Session
Sep 28
QP 22 - Refining Prostate Cancer Care: Integration, Innovation, and Outcomes

LBA 24 - Multicenter MRI-Only vs. CT planning for Prostate Cancer: Implementation, Dosimetry and Two-Year Quality of Life Outcomes

05:05pm - 05:10pm ET
Room 205

Presenter(s)

Tony Young, PhD Headshot
Tony Young, PhD - Liverpool and Macarthur Cancer Therapy Centres, Liverpool Hospital, Liverpool, NSW

T. Young1, J. Dowling2, J. M. Martin3,4, M. Sidhom1,5, K. Wong1, M. Richardson6, K. Skehan6, D. Wilkinson7, A. Miller8, S. Sridharan6, Y. Trada6, S. F. Liu9, M. Lehman9,10, E. Cosgriff11, J. Lye12, E. S. Choong13, A. Scott14, C. I. Tang14, and P. Greer6; 1Liverpool and Macarthur Cancer Therapy Centres, Sydney, Australia, 2Australian e-Health Research Centre, CSIRO, Brisbane, Australia, 3GenesisCare Gateshead, Newcastle, NSW, Australia, 4Calvary Hospital Newcastle, Newcastle, Australia, 5South Western Sydney Clinical School, University of New South Wales, Sydney, Australia, 6Radiation Oncology Calvary Mater Newcastle Hospital, Newcastle, Australia, 7Department of Radiation Oncology, Illawara Cancer Care Centre, Wollongong, Australia, 8Department of Radiation Oncology, Illawarra Cancer Care Centre, Wollongong, Australia, 9Radiation Oncology, Princess Alexandra Hospital, Brisbane, Australia, 10Royal Australian and New Zealand College of Radiologists, Brisbane, Australia, 11Department of Radiation Oncology, The Crown Princess Mary Cancer Centre, Westmead, Australia, 12Australian Clinical Dosimetry Service - ARPANSA, Melbourne, Australia, 13Olivia Newton John Cancer Centre, Austin Health, Melbounre, VIC, Australia, 14Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, Australia

Purpose/Objective(s):

MRI-only prostate radiotherapy treatment planning may be an alternative to CT-based planning methods. Although MR-only plans are dosimetrically similar to CT plans, there are no multicenter clinical outcome data to fully validate this approach. This study presents a multi-phase MRI-only treatment planning implementation approach conducted within the auspices of a randomized clinical trial - to determine for the first time if MRI-only planning is equivalent in quality-of-life outcomes to conventional CT planning.

Materials/Methods:

TROG 1801 NINJA is an open-label, randomized, controlled phase 3 trial comparing two ultrahypofractionated regimens conducted at 20 centers in Australia and New Zealand. Recruitment is currently 471/472. The trial has HREC approval and is prospectively registered (ANZCTN 12615000223538). Eight centers participated in an MRI-only sub-study. A three-phase implementation model was adopted, where centers performed retrospective analysis of MRI-only plans for five patients, followed by prospective MRI-only plans compared to CT calculated plans for ten patients. Following this, prospective MRI-only plans were compared to plans calculated on a Bulk Anatomical Density bone-tissue map (BADBT). For all three phases 3D gamma evaluation was performed in additional to isocenter dose and DVH comparison. Expanded Prostate Cancer Index Composite-26 (EPIC-26) Quality of Life (QoL) assessments at baseline and 24 months following radiotherapy were compared between MRI-only and CT planned patients, assessing minimally clinically important differences in gastrointestinal and genitourinary side-effects.

Results: A total of 189 patients randomised across the two treatment fractionations have completed treatment on the MRI-only sub-study. Isocentre dose agreement against CT or BADBT calculated plans was on average -0.7% ± 1.0%, with 2%,2mm (10% dose threshold) gamma agreement on average 99.9% ± 0.5%.

A total of 286 patients (116 patients on the MRI-only arm) have reached 2 year follow-up, and QoL completion rate was >95% at all timepoints. A Kruskal-Wallis test comparing EPIC-26 QoL scores for MRI planned patients to CT planned patients showed no statistically significant results at baseline, 6 week follow up and 2 year follow up for GU obstructive (baseline p = 0.985, 6 weeks p = 0.102, 24 months p = 0.074), GU irritative (baseline p = 0.890, 6 weeks p = 0.102, 24 months p = 0.097), or GI (baseline p = 0.941, 6 weeks p = 0.152, 24 months p = 0.151) across the two treatment arms.

Conclusion: The MRI-only sub-study has demonstrated that this major change in planning technique and workflow can be implemented safely and effectively in a multi-centric setting using a three-phase approach. At two years, MRI-only planning for prostate cancer has been demonstrated to have equivalent QoL outcomes as conventional CT planning.