The Clinical Significance of Maximum Tumor Diameter on MRI in Men Undergoing Radical Prostatectomy or Definitive Radiotherapy for Locoregional Prostate Cancer.

Maximum tumor diameter (MTD) on pretreatment magnetic resonance imaging (MRI) has the potential to further risk stratify for men with prostate cancer (PCa) prior to definitive local therapy. We aim to evaluate the prognostic impact of radiographic maximum tumor diameter (MTD) in men with localized prostate cancer.

From a single-center retrospective cohort of men receiving definitive treatment for PCa (radical prostatectomy [RP] or radiotherapy [RT]) with available pretreatment MRI, we conducted univariable and multivariable Cox proportional-hazards models for progression using clinical variables including age, NCCN risk group, radiographic extracapsular extension (ECE), radiographic seminal vesical invasion (SVI), and MTD. RP and RT cohorts were analyzed separately. Covariates were used in a classification and regression tree (CART) analysis and progression-free survival was estimated with the Kaplan-Meier method and groups were compared using log-rank tests.

The cohort included 631 patients (n = 428 RP, n = 203 RT). CART analysis identified 4 prognostic groups for patients treated with RP and 2 prognostic groups in those treated with RT. In the RP cohort, NCCN low/intermediate risk group patients with MTD>=15 mm had significantly worse PFS than those with MTD <= 14 mm, and NCCN high-risk patients with radiographic ECE had significantly worse PFS than those without ECE. In the RT cohort, PFS was significantly worse in the cohort with MTD >= 23 mm than those <= 22 mm.

Radiographic MTD may be a useful prognostic factor for patients with locoregional prostate cancer. This is the first study to illustrate that the importance of pretreatment tumor size may vary based on treatment modality.

Clinical genitourinary cancer. 2022 Jun 14 [Epub ahead of print]

Ryan Hutten, Ashley Khouri, Matthew Parsons, Alex Tward, Trevor Wilson, John Peterson, Glen Morrell, Christopher Dechet, Brock O'Neil, Bogdana Schmidt, Kristine Kokeny, Shane Lloyd, Donald Cannon, Jonathan Tward, Alejandro Sanchez, Skyler Johnson

Department of Radiation Oncology, Huntsman Cancer Hospital, University of Utah, Salt Lake City, UT., University of Utah School of Medicine, Salt Lake City, UT., Department of Radiology and Imaging Services, University of Utah, Salt Lake City, UT., Division of Urology, Department of Surgery, Huntsman Cancer Hospital, University of Utah, Salt Lake City, UT., Department of Radiation Oncology, Huntsman Cancer Hospital, University of Utah, Salt Lake City, UT. Electronic address: .

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