ESTRO 2023

Session Item

Urology

Session Code: 6018

Session Type: Poster (Digital)

Track: Clinical

Adjuvant radiotherapy of prostate cancer: a comprehensive analysis of toxicity predictors

Letizia Cavallini, Italy

Presentation Number: PO-1474

Abstract

Abstract Title:

Adjuvant radiotherapy of prostate cancer: a comprehensive analysis of toxicity predictors

Authors:

Letizia Cavallini¹, Claudio Malizia², Gabriella Macchia³, Maria Ntreta⁴, Alessandra Arcelli⁴, Filippo Mammini¹, Erika Galietta¹, Silvia Paolinelli¹, Viola Laghi¹, Daria Vallerossa¹, Elena Natoli¹, Savino Cilla⁵, Silvia Bisello¹, Annalisa Cortesi⁶, Silvia Cammelli¹, Giovanni Piero Frezza⁷, Alessio Giuseppe Morganti¹, Francesco Deodato⁸, Milly Buwenge¹

¹Radiation Oncology, Department of Experimental, Diagnostic and Specialty Medicine-DIMES, Alma Mater Studiorum University of Bologna, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; ²Nuclear Medicine, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; ³Radiation Oncology Unit, Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Campobasso, Italy; ⁴Radiation Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; ⁵Medical Physics Unit, Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Campobasso, Italy; ⁶Radiotherapy Unit, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", Meldola, Italy; ⁷Radiotherapy Department, Ospedale Bellaria, Bologna, Italy; ⁸Radiation Oncology Unit, Istituto di Radiologia, Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Università Cattolica del Sacro Cuore , Campobasso, Roma, Italy

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Purpose or Objective

The aim of this study was to analyze the prognostic impact on toxicity, in patients with prostate cancer treated with adjuvant radiotherapy, of several patients and treatment characteristics.

Material and Methods

Both acute and late toxicity were assessed in this observational study (ICAROS-1). The recorded and evaluated patients-related characteristics were age and Charlson’s comorbidity index. Analyzed treatment characteristics were: delivery of prophylactic lymph nodes irradiation, previous TURP, use of adjuvant ADT and its type (LH-RH analogues or high-dose Bicalutamide) and duration, RT fractionation and technique (including type of image-guidance systems), and Equivalent Dose in 2 Gy/fraction (EQD2) to the prostate bed and pelvic lymph nodes. Late toxicity-free survival curves were calculated by the Kaplan-Meier product-limit method and compared with the log-rank test. Variables with p value less than 0.05 or with a trend (p < 0.1) at univariate analysis were entered into a multivariate Cox’s regression model. Acute toxicity was assessed by RTOG scale while late toxicity was evaluated with the RTOG/EORTC scale.

Results

Three-hundred-eighty-one patients were enrolled. Acute GI and GU G3 toxicity rates were 0.5% and 1.3%, respectively. Median EQD2 to the prostate bed (α/β=1.5) was 71.4 Gy. Most patients (75.4%) were treated with IMRT/VMAT techniques. No patient showed G>3 acute toxicity. At multivariable logistic regression only younger age (< 65 years) was significantly correlated with increased acute toxicity (both GI and GU). Five-year GI and GU grade ≥ 3 late toxicity-free survival was 98.1% and 94.5%, respectively. The only significant correlation at Cox’s regression model was in terms of reduced risk of GI toxicity in patients undergoing hypofractionation (HR: 0.38; 95%CI: 0.18-0.78; p: 0.008)

Conclusion

"Modern" postoperative radiotherapy is safe, both in terms of acute and late effects, also in subjects undergoing hypofractionated regimens and especially in elderly patients.