The impact of benign tissue within cancerous regions in the prostate: Characterizing sparse and dense prostate cancers on whole-mount histopathology and on multiparametric MRI

Olga Starobinets; Jeffry P Simko; Matthew Gibbons; John Kurhanewicz; Peter R Carroll; Susan M Noworolski

doi:10.1016/j.mri.2024.110233

The impact of benign tissue within cancerous regions in the prostate: Characterizing sparse and dense prostate cancers on whole-mount histopathology and on multiparametric MRI

Magn Reson Imaging. 2024 Dec:114:110233. doi: 10.1016/j.mri.2024.110233. Epub 2024 Sep 10.

Authors

Olga Starobinets¹, Jeffry P Simko², Matthew Gibbons³, John Kurhanewicz⁴, Peter R Carroll⁵, Susan M Noworolski⁶

Affiliations

¹ Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94143, USA; The Graduate Group in Bioengineering, University of California, San Francisco and Berkeley, Berkeley, CA 94720, USA.
² Department of Pathology, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Urology, University of California, San Francisco, San Francsico, CA 94143, USA; UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address: Jeff.Simko@ucsf.edu.
³ Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address: Matthew.Gibbons@ucsf.edu.
⁴ Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94143, USA; The Graduate Group in Bioengineering, University of California, San Francisco and Berkeley, Berkeley, CA 94720, USA; UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address: John.Kurhanewicz@ucsf.edu.
⁵ Department of Urology, University of California, San Francisco, San Francsico, CA 94143, USA; UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address: Peter.Carroll@ucsf.edu.
⁶ Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94143, USA; The Graduate Group in Bioengineering, University of California, San Francisco and Berkeley, Berkeley, CA 94720, USA; UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address: Susan.Noworolski@ucsf.edu.

PMID: 39260625
DOI: 10.1016/j.mri.2024.110233

Abstract

Purpose: To establish the incidence, size, zonal location and Gleason Score(GS)/Gleason Grade Group(GG) of sparse versus dense prostate cancer (PCa) lesions and to identify the imaging characteristics of sparse versus dense cancers on multiparametric MRI (mpMRI).

Methods: Seventy-six men with untreated PCa were scanned prior to prostatectomy with endorectal-coil 3 T MRI including T2-weighted imaging, diffusion-weighted imaging and dynamic contrast-enhanced MRI. Cancerous regions were outlined and graded on the whole-mount, processed specimens, with tissue compositions estimated. Regions with cancer comprising <50 % and ≥ 50 % of the tissue were considered sparse and dense respectively. Regions of interest (ROI) were manually drawn on T2-weighted MRI. Within each patient, area-weighted ROI averages were calculated for each imaging measure for each tissue type, GS/GG, and sparse/dense composition.

Results: A large number of cancer regions were identified on histopathology (n = 1193: 939 (peripheral zone (PZ)) and 254 (transition zone (TZ))). Thirty-seven percent of these lesions were sparse. Sparse lesions were primarily low-grade with the majority of PZ and 100 % of TZ sparse lesions ≤GS3 + 3/GG1. Dense lesions were significantly larger than sparse lesions in both PZ and TZ, p < 0.0001. On imaging, 246/45 PZ and 109/8 TZ dense/sparse 2D cancerous ROIs were drawn. Sparse GS3 + 3 and sparse ≥GS3 + 4 cancers did not have significantly different MRI intensities to dense GS3 + 3 cancers, while sparse GS3 + 3/GG1 cancers differed from benign, p < 0.05.

Conclusion: Histopathologically identified prostate cancer lesions were sparse in 37 % of cases. Sparse cancers were entirely low grade in TZ and predominantly low-grade in PZ and generally small, thus likely posing lower risk for spread and progression than dense lesions. Sparse lesions were not distinguishable from dense lesions on mpMRI, but could be distinguished from benign tissues.

Keywords: Histopathology; Multiparametric MRI; Prostate cancer; Prostatectomy.

MeSH terms

Aged
Humans
Magnetic Resonance Imaging / methods
Male
Middle Aged
Multiparametric Magnetic Resonance Imaging*
Neoplasm Grading*
Prostate* / diagnostic imaging
Prostate* / pathology
Prostatectomy
Prostatic Neoplasms* / diagnostic imaging
Prostatic Neoplasms* / pathology