Impact of PI-RADS During Active Surveillance for Prostate Cancer on Pathological Findings at Repeat Biopsy

Sep 23, 2026

Background/Aim: Determine whether lesion visibility on prostate MRI predicts repeat-biopsy outcomes during active surveillance for prostate cancer. Patients and Methods: Retrospective analysis of 111 PRIAS-Japan participants at Kagawa University (Jan 2010–Feb 2025), excluding 19 who discontinued within one year; 92 analyzed. MRI visibility was PI-RADS ≥3 (visible) vs ≤2 (invisible), with outcomes defined as pathological reclassification beyond AS criteria or no cancer. Results: At 1-year rebiopsy, reclassification was more frequent with visible lesions (42.1% vs 7.1%, p=0.047) and no cancer was more common with invisible lesions (50.0% vs 10.5%, p=0.019). Conclusion: PI-RADS ≥3 increased reclassification risk at one year, while PI-RADS ≤2 indicated higher likelihood of no cancer, supporting MRI’s prognostic value in AS guidance.

LanguageEnglish

CategoryHealthcare

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Pages9

Reading Time23 min

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Abstract

Background/Aim

Patients and Methods

Results

Conclusion

Introduction

Active surveillance overview

Role of MRI and PI-RADS

Study objective

Patients and Methods

Study design and patient population

doi: 10.21873/invivo.14448 Impact of PI-RADS During Active Surveillance for Prostate Cancer on Pathological Findings at Repeat Biopsy YOICHIRO TOHI1, KENICHI TANAKA2, TAKUMA KATO1, KENGO FUJIWARA1, ASUKA KAJI1, SATOSHI HARADA1, KANA KOHASHIGUCHI1, YOHEI ABE1, HIROHITO NAITO1, HOMAREOKAZOE1, RIKIYATAOKA1, NOBUFUMI UEDA1, YOSHIHIRO NISHIYAMA2 and MIKIO SUGIMOTO1 1 Department of Urology, Faculty of Medicine, Kagawa University, Kagawa, Japan; 2 Department of Radiology, Faculty of Medicine, Kagawa University, Kagawa, Japan Abstract Background/Aim: This study aimed to determine whether lesion visibility on magnetic resonance imaging (MRI) predicts rebiopsy outcomes during active surveillance for prostate cancer. Patients and Methods: We retrospectively analyzed data from 111 patients enrolled in the Prostate Cancer Research International Active Surveillance study (Japan) at Kagawa University (January 2010–February 2025). After excluding 19 patients who discontinued active surveillance within one year, 92 patients were included in the analysis. MRI findings were classified as visible [Prostate Imaging Reporting and Data System (PI-RADS) score ≥3] or invisible (score ≤2). We assessed the association between visibility and rebiopsy outcomes, defined as reclassification progression beyond active surveillance criteria or no cancer. Results: MRI was performed at diagnosis in 32.6%(n=32) of patients, at one year in 37.0%(n=34), and at four years in 47.7%(n=21). Lesion visibility at diagnosis was not associated with continuation of active surveillance compared with invisibility [median 43 months, 95% confidence interval (12-not available) vs. not available (17-not available), p=0.404] . However, at the 1-year rebiopsy, reclassification occurred significantly more frequently in patients with visible lesions than in those with invisible lesions (42.1% vs. 7.1%, p=0.047). Conversely, no cancer was more common in patients with invisible lesions (50.0% vs. 10.5%, p=0.019) . Conclusion: At one year, a PI-RADS score ≥3 was associated with a higher risk of reclassification, whereas a score ≤2 was associated with a greater likelihood of no cancer on rebiopsy. These findings highlight the prognostic value of MRI in guiding active surveillance. Keywords: Active surveillance, magnetic resonance imaging, Prostate Imaging Reporting and Data System, prostate cancer, reclassification. ✉Yoichiro Tohi (ORCID: 0000-0003-3884-8915), Department of Urology, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan. Tel: +81 878982202, Fax: +81 878912203, [e-mail: yoto716yotoyoto@gmail.com](e-mail: yoto716yotoyoto@gmail.com) Received June 14, 2026 | Revised July 9, 2026 | Accepted July 22, 2026 This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. ©2026 The Author(s) . Published by the International Institute of Anticancer Research. Introduction Active surveillance (AS) is a standard management strategy for low-and select intermediate-risk prostate cancer (PCa), aimed at minimizing overtreatment while maintaining oncological safety (1-3) . Accumulating evidence supports the safety of AS for PCa (4-6) . Recently, magnetic resonance imaging (MRI) has emerged as an essential component of AS protocols (7, 8) . Baseline MRI findings at diagnosis correlate with tumor aggressiveness and future reclassification risk (7, 9) . Men with MRI-visible lesions [Prostate Imaging Reporting and Data System (PI-RADS) score ≥3] at enrollment are significantly more likely to undergo reclassification on follow-up biopsy compared to those without suspicious MRI findings (9) . Conversely, when MRI is negative or shows low suspicion (PI-RADS 1-2), the negative predictive value for significant cancer is high, indicating a low risk of early reclassification (10) . Radio

FAQs

What was the study’s main aim regarding PI-RADS and active surveillance?

To determine whether prostate MRI lesion visibility predicts repeat-biopsy outcomes during active surveillance.

How were MRI lesions categorized in this study?

Lesion visibility was classified as visible when PI-RADS ≥3 and invisible when PI-RADS ≤2.

What did the study find at the 1-year rebiopsy?

Reclassification occurred significantly more often in patients with visible lesions (42.1% vs 7.1%), while no cancer was more common in those with invisible lesions (50.0% vs 10.5%).

Sep 23, 2026

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