Endorectal magnetic resonance imaging for risk classification of localized prostate cancer: Radiographic findings and influence on treatment decisions.

To the Editor: We appreciated the article of Liauw et al. [1] about the endorectal magnetic resonance imaging (MRI) and its influence in radiotherapeutic management. The influence of the 3 T endorectal MRI staging on the final radiotherapy (RT) treatment decision was analyzed in a total of 122 patients with prostate cancer. Briefly, in that study, the initially planned treatment was modified in 18% of patients. Surprisingly, the authors stated the following within the discussion: “There are no reports to our knowledge, which address the role of MRI on clinical decision-making from the radiation oncologist's perspective.” However, our group has already published 2 studies analyzing the influence on final decisions in RT treatment of 3 T multiparametric MRI (mpMRI) without endorectal coil [2,3]. In our series, with a total of 274 patients [3], the global change in the risk groups when considering all factors, such as prostate-specific antigen levels, Gleason score, and tumor category, occurred in 32.8% of patients. Our results are comparable to an article published by Panje et al. [4] (28.7%). According to these data, we might say that at least 18% to 32% of patients with prostate cancer staged with mpMRI with or without endorectal coil could face an alteration of the final RT treatment decision. We obtained a global alteration of RT treatment in 43.8% or 52.5% of patients (depending on hormone therapy [HT] criteria for intermediate-risk patients). Other studies have shown a change in RT treatment of between 8% and 34% [5–8]. Such variability can be due to several causes previously described [3], such as factors related to MRI (magnet and coil, the use of functional sequences, expertise of the radiologist, the use of previous HT, etc.); factors related to the initial clinical staging (expertise of the clinician for the digital rectal examination/transrectal ultrasound, the use of computerized tomography scan to evaluate pelvic lymph nodes, etc.); clinical features of the cohorts of patients included in the studies; factors related to the RT treatment given in each center (doses, fractionation, target volume, HT indication, brachytherapy use, etc.); and