Predicting genitourinary toxicity in three-dimensional conformal radiotherapy for localized prostate cancer: A dose-volume parameters analysis of the bladder.

In prostate cancer radiotherapy, the relationship between genitourinary (GU) toxicity and clinical-dosimetric parameters is debated. We report our analysis of the parameters associated with GU toxicity.

Eighty-six consecutive patients treated with conformal radiotherapy for localized prostate cancer were retrospectively analyzed; the bladder was delineated both as "whole bladder" (WB: Defined in its entirety as a solid organ) and "inferior bladder" (IB: Corresponding to the distal part of the bladder). GU toxicity and dose-volume parameters were correlated using the point biserial correlation coefficient. The normal tissue complication probability (NTCP) cut-off volume model was fitted to toxicity data; univariate analysis between GU toxicity and clinical parameters was done.

Acute GU toxicity was correlated to doses higher than 80 Gy (P < 0.05) while late GU was correlated to doses higher than 77 Gy for WB and from 77.5 Gy for IB. The NTCP cut-off volume model identified for both WB and IB a bladder volume of 6 cc receiving a dose ≥77 Gy corresponding to a 50% probability of GU toxicity. At univariate analysis, acute GU toxicity was correlated with smoke (P < 0.001).

Bladder maximal doses quantified as hotspots show a correlation to GU toxicity.

Journal of cancer research and therapeutics. 0000 [Epub]

Paolo Bagalà, Gianluca Ingrosso, Maria Daniela Falco, Sara Petrichella, Marco D'Andrea, Maria Rago, Andrea Lancia, Claudia Bruni, Elisabetta Ponti, Riccardo Santoni

Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, University of Rome Tor Vergata, Viale Oxford 81, 00133 Rome, Italy., Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, University of Rome Tor Vergata, Viale Oxford 81, 00133 Rome, Italy., Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, University of Rome Tor Vergata, Viale Oxford 81, 00133 Rome, Italy., Computer Science and Bioinformatics Laboratory, Integrated Research Centre, Campus Bio-Medico University, Via Alvaro del Portillo 21, 00128, Rome, Italy., Laboratory of Medical Physics and Expert Systems, National Cancer Institute Regina Elena, V. E. Chianesi 53, 00144 Rome, Italy., Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, University of Rome Tor Vergata, Viale Oxford 81, 00133 Rome, Italy., Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, University of Rome Tor Vergata, Viale Oxford 81, 00133 Rome, Italy., Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, University of Rome Tor Vergata, Viale Oxford 81, 00133 Rome, Italy., Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, University of Rome Tor Vergata, Viale Oxford 81, 00133 Rome, Italy., Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, University of Rome Tor Vergata, Viale Oxford 81, 00133 Rome, Italy.