The Prevalence of Prostate Cancer in Biopsy Samples of Lesions with PI-RADS 2 Score in Multiparametric Magnetic Resonance Imaging: A Cross-Sectional Study

Background: Prostate cancer (PC) is one of the most common cancers worldwide. Recently, multiparametric magnetic resonance imaging (mpMRI) has been used to diagnose PC in suspected patients. Prostate Imaging Reporting & Data System (PI-RADS) was developed and applied as a criterion for detecting lesions suspicious of PC. Various studies have been conducted to determine the negative predictive value of non-suspicious mpMRI (PI-RADS 1 or 2). However, the results of these studies have been limited and different. Objectives: This study was conducted to determine the PC rate in patients with PI-RADS 2 lesions in mpMRI and the factors related to clinically significant prostate cancer (CsPC) diagnosis in these lesions. Methods: By referring to the archive department of Shahada-e-Tajrish, Rasul-e-Akram, Treata, and Payambaran hospitals, among the patients suspected of PC who underwent biopsy and had elevated prostate-specific antigen (PSA) serum levels, the prostate biopsy samples of 330 patients were consecutively included in the study. Frequency of samples diagnosed with PC and its histological characteristics, including mass location, Gleason score (GS), Gleason group (GG), percentage of G4 and G5 cells, sample size, percentage of involvement of sample with cancer tissue, and invasion to the surrounding tissues were examined. Adenocarcinoma samples were divided into low-risk, intermediate-to-high-risk groups based on D'Amico criteria and the relationship between age, PSA total (PSAt), PSA density (PSAd), prostate volume, and the presence of a PI-RADS 3 or 4 lesion at the same time with the rate of diagnosed CsPCs were reviewed. Results: The data from 709 tissue samples were collected, among which 249 were from the right inner part, 249 were from the left inner part, and 211 biopsy samples were from the peripheral portion of the prostate. Among these, 390 tissue samples in mpMRI studies were PI-RADS 2, and 319 were PI-RADS 3 or 4. The mean age of the patients was 64.78 ± 37.55. The mean PSAd, PSAt, and prostate volume were 0.15 ± 0.11, 8.73 ± 6.43, and 61.18 ± 25.76, respectively. Seventy-five samples were diagnosed with adenocarcinoma, of which 48% are in PI-RADS group 2, and 52% are in PI-RADS group 3 - 4 (P-value = 0.263). Comparing the histological characteristics of adenocarcinoma samples between the two groups showed that only the amount of GG was significantly higher in the samples with PI-RADS 3 and 4 (P-value = 0.035). Adenocarcinomas diagnosed in 72.2% of cases in PI-RADS 2 samples and 84.6% of PI-RADS 3 and 4 samples were clinically significant, and no significant difference was seen between the two groups (P-value = 0.38). The amount of PSAt in PI-RADS 2 adenocarcinoma samples was significantly higher in clinically significant carcinomas than in low-risk carcinomas (P-value = 0.045). Conclusions: The results of the present study showed that PI-RADS 2 lesions should be considered for biopsy when there is clinical suspicion of PC. PSA levels can effectively determine the need for biopsy in PI-RADS 2 lesions.