ESTRO 2023

Session Item

Sunday

May 14

15:15 - 16:15

Business Suite 1-2

Urology

Chair: Giulio Francolini, Italy

Session Code: 2450

Session Type: Poster Discussion

Track: Clinical

MRI before salvage radiotherapy after radical prostatectomy in prostate cancer: a case-control study

Letizia Cavallini, Italy

Presentation Number: PD-0566

Abstract

Abstract Title:

MRI before salvage radiotherapy after radical prostatectomy in prostate cancer: a case-control study

Authors:

Letizia Cavallini¹, Caterina Gaudiano², Erika Galietta¹, Filippo Mammini¹, Silvia Paolinelli¹, Viola Laghi¹, Daria Vallerossa¹, Elena Natoli¹, Alessio Giuseppe Morganti¹, Alessandra Arcelli³, Silvia Cammelli¹, Gabriella Macchia⁴, Francesco Deodato⁵, Rita Golfieri⁶, Giovanni Piero Frezza⁷, Maria Ntreta³

¹Radiation Oncology, Department of Experimental, Diagnostic and Specialty Medicine-DIMES, Alma Mater Studiorum University of Bologna, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; ²Department of Radiology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; ³Radiation Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; ⁴Radiation Oncology Unit, Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Campobasso, Italy; ⁵Radiation Oncology Unit, Istituto di Radiologia, Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Università Cattolica del Sacro Cuore, Campobasso, Roma, Italy; ⁶Department of Radiology, IRCCS Azienda Ospedaliero-Universitaria, Bologna, Italy; ⁷Radiotherapy Department, Ospedale Bellaria, Bologna, Italy

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Purpose or Objective

Current international guidelines recommend choline-PET or PSMA-PET in patients with prostate cancer candidates for salvage radiotherapy (RT) to rule out the presence of lymph node or hematogenous metastases prior to RT. However, in our centers, we tested the use of pelvic MRI in order to evaluate its effectiveness in detecting locoregional relapses and therefore to optimize salvage RT. Therefore, the aim of this analysis is to compare two matched cohorts of patients who underwent or did not undergo MRI before salvage RT in terms of biochemical disease control.

Material and Methods

One hundred sixteen patients from three centres were included in this study. Patients in the two cohorts were matched according to: PSA before SRT (<0.2; 0.2-0.5; 0.5-1.0; >1.0 ng/ml), pathological tumor stage, ISUP grade group (1, 2, 3, 4, 5), pelvic nodal irradiation, and adjuvant hormonal therapy. Kaplan-Meier survival curves were compared using the log-rank test. This analysis is part of a multicenter observational study (ICAROS trial) approved by the ethics committees of the participating centers.

Results

Macroscopic locoregional relapse was identified in forty-two/58 patients (72.4%) undergoing pelvic MRI and therefore these patients were treated with a median total dose of 70.4 Gy (range: 66-72.6), while patients without MRI or with negative MRI received a median total dose of 66 Gy (range: 62.5-72.0). Indeed, in patients with MRI-detected relapse, a focal boost (sequential or concomitant) was administered with a median dose of 4.4 Gy (range: 4.4-70.5). Overall, comparing the cohorts of patients who underwent and did not undergo MRI, a significantly higher rate of biochemical relapse-free survival was recorded in the first group (2-year rates: 91.5% versus 73.6%; p = 0.006; Figure 1).

Figure 1: Biochemical relapse-free survival in patient undergoing MRI (green) and not undergoing MRI (blue) before salvage radiotherapy (p<0.001).

Conclusion

An unexpectedly and surprisingly high rate of macroscopic relapses was recorded in patients undergoing MRI prior to salvage RT. This made it possible to adapt the treatment by delivering a boost to the disease site. This strategy produced a significant improvement in the biochemical outcome of these patients. Our findings challenge current guidelines on the pre-treatment restaging in this setting.