European Journal of Radiology 85 (2016) 2231–2237 Contents lists available at ScienceDirect European Journal of Radiology j ourna l h om epage: www.elsevier.com/locate/ejrad Can multiparametric MRI replace Roach equations in staging prostate cancer before external beam radiation therapy? Rossano Girometti a,∗ , Marco Andrea Signor b , Martina Pancot a , Lorenzo Cereser a , Chiara Zuiani a a Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, University of Udine, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia - via Colugna, 50–33100, Udine, Italy b Department of Oncological Radiation Therapy, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia, Piazzale S. M. della Misericordia, 15–33100, Udine, Italy a r t i c l e i n f o Article history: Received 21 July 2016 Received in revised form 27 September 2016 Accepted 21 October 2016 Keywords: Prostate cancer External beam radiation therapy Roach equations Magnetic resonance imaging T stage a b s t r a c t Purpose: To investigate the agreement between Roach equations (RE) and multiparametric magnetic resonance imaging (mpMRI) in assessing the T-stage of prostate cancer (PCa). Materials and methods: Seventy-three patients with biopsy-proven PCa and previous RE assessment prospectively underwent mpMRI on a 3.0T magnet before external beam radiation therapy (EBRT). Using Cohen’s kappa statistic, we assessed the agreement between RE and mpMRI in defining the T- stage (≥T3 vs.T ≤ 2) and risk category according to the National comprehensive cancer network criteria (≤intermediate vs. ≥high). We also calculated sensitivity and specificity for ≥T3 stage in an additional group of thirty-seven patients with post-prostatectomy histological examination (mpMRI validation group). Results: The agreement between RE and mpMRI in assessing the T stage and risk category was moderate (k = 0.53 and 0.56, respectively). mpMRI changed the T stage and risk category in 21.9% (95%C.I. 13.4–33- 4) and 20.5% (95%C.I. 12.3–31.9), respectively, prevalently downstaging PCa compared to RE. Sensitivity and specificity for ≥T3 stage in the mpMRI validation group were 81.8% (95%C.I. 65.1–91.9) and 88.5% (72.8–96.1). Conclusion: RE and mpMRI show moderate agreement only in assessing the T-stage of PCa, translating into an mpMRI-induced change in risk assessment in about one fifth of patients. As supported by high sensitivity/specificity for ≥T3 stage in the validation group, the discrepancy we found is in favour of mpMRI as a tool to stage PCa before ERBT. © 2016 Elsevier Ireland Ltd. All rights reserved. 1. Introduction External beam radiation therapy (EBRT) has gained widespread acceptance as definitive treatment for prostate cancer (PCa). EBRT is indicated in all patients with non-metastatic disease, using intensity-modulated radiation therapy (IMRT) as the technical standard to deliver highly conformal treatments [1]. Most influencing factors affecting EBRT planning are cancer T stage, prostatic specific antigen (PSA) level and Gleason score (GS) after biopsy, which in turn are combined to stratify patients for the risk of PCa recurrence after therapy [1,2]. In accordance with ∗ Corresponding author. E-mail addresses: rgirometti@sirm.org (R. Girometti), marco.signor@asuiud.sanita.fvg.it (M.A. Signor), martypancot@libero.it (M. Pancot), lcereser@sirm.org (L. Cereser), chiara.zuiani@uniud.it (C. Zuiani). risk categories, EBRT regimens can be modulated in terms of dose, volume, fractionation and duration of concomitant androgen depri- vation therapy (ADT) [2,3]. However, clinical determination of the T stage is still a major challenge [1,2], leading to widespread use of nomograms as a tool to increase the sensitivity in predicting organ-confined (stages T1-T2) vs. extraprostatic disease (stages T3- T4) [4]. Roach equations (RE) combine Gleason Score (GS) and the PSA level to estimate the individual risk of extracapsular extension (ECE) (stage T3a) and seminal vesicle invasion (SVI) (stage T3 b) [5–7] and in turn to take a “go or no-go” decision on how extended the clinical target volume should be [8]. In patients with PCa addressed to EBRT, final pathological proof will lack by definition, thus emphasizing the need for planning the treatment based on the most objective available evidence of dis- ease extension. Despite the limited capability of mpMRI in assessing microscopic T3a stage, this technique is regarded as the method of http://dx.doi.org/10.1016/j.ejrad.2016.10.023 0720-048X/© 2016 Elsevier Ireland Ltd. All rights reserved.