ESTRO 2023 - Abstract Book

S151

Saturday 13 May

ESTRO 2023

Conclusion Hy-IGIM-RT schedules, although applying higher biologically equivalent doses compared to those of previous randomized trials, resulted well tolerated without worsening acute and late toxicity in comparison with the StD-RT ones. If efficacy endpoints also indicate at least equivalence, the Hy-IGIM-RT schedules tested may be taken into consideration for the treatment of selected low and intermediate-risk PC pts. MO-0217 Pattern of relapse following hypofractionated radiotherapy of IR prostate cancer in the PROFIT trial M. Lange 1 , L. Ollivier 2 , M. Renouf 3 , N. Magne 4 , I. Latorzeff 5 , P. Pommier 6 , E. Martin 7 , A. Pommier 8 , G. Béra 9 , C. Catton 10 , K. Zhou 11 , M. Bellanger 12 , J. Martin 13 , S. Supiot 14 1 Institut de Cancérologie de l'Ouest René Gauducheau, Radiation Oncology, Saint-Herblain, France; 2 Institut de Cancérologie de l'Ouest René Gauducheau, Radiation Oncology, Saint-Herblain, France; 3 Centre hospitalier départemental , Radiation Oncology, La Roche Sur-Yon, France; 4 Institut de Cancérologie et d'Hématologie Universitaire de Saint-Étienne, Radiation Oncology, Saint Priest en Jarez, France; 5 Oncorad Clinique Pasteur, Radiation Oncology, Toulouse, France; 6 Institut de Cancérologie de l'Ouest Paul Papin, University of Angers, Radiation Oncology, Angers, France; 7 Centre Georges-François Leclerc, Radiation Oncology, Dijon, France; 8 Institut de Cancérologie de l'Ouest Paul Papin, Radiation Oncology, Angers, France; 9 Hôpital du Scorff, Groupe Hospitalier Bretagne Sud, Radiation Oncology, Lorient, France; 10 Princess Margaret Cancer Centre, University of Toronto, Radiation Oncology, Toronto, Canada; 11 Institut de Cancérologie de l'Ouest, Human and Social Sciences, Saint-Herblain, France; 12 UMR CNRS6051 Rennes1 – EHESP School of Public Health, Human and Social Sciences, Rennes, France; 13 Calvary Mater Hospital, University of Newcastle, Radiation Oncology, Newcastle, Australia; 14 Institut de Cancérologie de l’Ouest René Gauducheau, Radiation Oncology, Saint-Herblain, France Purpose or Objective To analyze the differential pattern of relapse of hypofractionated radiotherapy (HRT) as compared to conventionally fractionated RT (CFRT) of intermediate-risk (IR) prostate cancers patients in the international randomized phase 3 “PROstate Fractionated Irradiation Trial (PROFIT)” study (NCT00304759). Materials and Methods We retrospectively described the anatomical site of relapse in biochemically-relapsing patients following HFRT (60 Gy in 20 f) or CFRT (78 Gy in 39f) based on 18F Choline PET-CT or 68Galium Prostate Specific Membrane Antigen (PSMA) PET-CT in patients treated in France and Australia. Local failure-free survival (LFS), pelvic lymph node metastasis-free survival (pnMFS), extra-pelvic lymph node metastasis-free survival (epnMFS), and bone metastasis-free survival (bMFS) were compared between both treatment arms using Kaplan-Meier analyses. Results Median follow-up was 6.6 y interquartile range (IR) 5.7-8.9. Among a total 274 patients (n= 130 HRT; n+ 144 CFRT), 35 patients (24.3%) in the HRT arm and 28 patients (19.4%) in the CFRT arm relapsed. The sites of relapse were local (n=35), pelvic lymph nodes (n=32), extra-pelvic lymph nodes (n=10) and bone (n=14). Median time to relapse was 4.9 y (IR 4.2-6.6) locally, 4.4 years (IR 2.8-5.3) for pelvic lymph nodes, 3.3 years (IR 1.9-4.6) for extra-pelvic lymph node, 3.8 years (IR 2.2- 5.8) for bone metastasis. No statistically significant difference was observed between HRT and CFRT arms in terms of LFS (HR 1.09 [0.561-2.11], p=0.8), pnMFS (HR 1.7 [0.837-3.44] p=0.14), epnMFS (HR 1.74 [0.491-6.17] p=0.39), or bMFS (HR 1.14 [0.401-3.26] p=0.8. Conclusion Relapse rate following HRT or CFRT is low in IR prostate cancer patients. Most relapses are loco-regional (prostate and/or pelvic lymph nodes). Loco-regional relapses occurred later than extra-pelvic and bone relapse. No significant difference in anatomical patterns of relapse was observed between HRT and CFRT arms.