ESTRO 2024 - Abstract Book

S2514

Clinical - Urology

ESTRO 2024

66 patients were treated within the OTT of 7 days, 28 patients within an OTT of 8-10 days and 4 patients within an OTT of more than 10 days. Reasons for OTT prolongation were diverse: too much air in the rectum, service on MRIdian, bank holidays, etc. Grade 0, 1, 2 and 3 acute GU toxicity was observed in 17, 52, 27 and 2 patients (see Figure 1). Grade 0, 1, 2 and 3 acute GI toxicity was observed in 39, 52, 7 and 0 patients respectively. No grade 4 or 5 acute toxicities were observed. Acute GI toxicity was observed to be significantly lower than reported in the PACE-B trial (7.1% [7/98] vs.15.7% [65/415]; p=0.028) For the late toxicity evaluation we cut the data collection at 1 year of follow-up, where currently 76 patients were eligible for evaluation. Data on 23 of these 76 patients is awaited from the referring hospitals at the time of this interim analysis. Of the remaining 53 patients, a late toxicity of grade 0 was observed in 29 and 46 patients, of grade 1 in 16 and 6 patients and of grade 2 in 8 and 1 patients for respectively GI and GU AEs (see Figure 1). No grade 3+ late toxicities were reported.

Conclusion:

The acute toxicity evaluation showed only 30% and 7% patients having grade 2+ toxicity GU and GI AEs. After one year follow-up we observed 15% GU and 2% GI late toxic effects. Our study shows that dose-escalation on the GTV using MRI-guided radiotherapy can be safely delivered with limited GI/GU toxicities.

Keywords: Prostate, MR-guided radiotherapy, Toxicities

References:

(1): Brand DH, Tree AC, Ostler P, van der Voet H, Loblaw A, Chu W, Ford D, et al; PACE Trial Investigators. Intensity modulated fractionated radiotherapy versus stereotactic body radiotherapy for prostate cancer (PACE-B): acute toxicity findings from an international, randomised, open-label, phase 3, non-inferiority trial. Lancet Oncol. 2019 Nov;20(11):1531-1543. doi: 10.1016/S1470-2045(19)30569-8. Epub 2019 Sep 17. PMID: 31540791; PMCID: PMC6838670.

JVL and JBB contributed equally and should therefore be considered joint first author

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