Detection rates for prostate cancer using PI-RADS 2.1 upgrading rules in transition zone lesions align with risk assessment categories: a systematic review and meta-analysis

Abstract

Objective: To evaluate and compare cancer detection rates (CDRs) of transition zone (TZ) lesions upgraded from PI-RADSv2.1 score 2 to 3 ("2 + 1") or from 3 to 4 ("3 + 1") using DWI and assess their clinical impact.

Materials and methods: A systematic literature search was performed in Embase, Medline, and Web of Science for studies assessing TZ lesions with DWI in PI-RADSv2.1, with histology-confirmed grade group ≥ 2 cancer (GG ≥ 2) as the primary outcome. Risk of bias was evaluated using QUADAS-2. Pooled sensitivity, specificity, CDRs, and odds ratios (ORs) were estimated at the lesion level using a bivariate binomial random-effects model.

Results: Eight studies with 1535 TZ lesions were included. GG ≥ 2 CDRs for PI-RADS scores of 1, 2, 2 + 1, 3, 3 + 1, 4, and 5 were 2% (95%CI: 0%-12%), 6% (4%-10%), 13% (6%-23%), 19% (15%-25%), 37% (24%-52%), 49% (32%-67%), and 73% (66%-79%), respectively. Scores of 2 + 1 had higher GG ≥ 2 CDRs than 2 (OR 3.37 (1.53-7.44), p = 0.003) but were similar to 3 (OR 0.80 (0.44-1.45), p = 0.46). Scores of 3 + 1 had higher GG ≥ 2 CDRs than 3 (OR 2.67 (1.27-5.59), p = 0.009) but were similar to 4 (OR 0.68 (0.33-1.44), p = 0.32). False-positive rates remained substantial (≥ 2 + 1: 69% (55%-80%); ≥ 3: 54% (46%-62%)).

Conclusion: The risk of having significant prostate cancer in "2 + 1" and "3 + 1" TZ lesions, with an upgrading based on DWI images, is appropriately categorized within the PI-RADS v2.1 scoring system, as shown by this meta-analysis.

Key points: Question PI-RADS v2.1 incorporates rules allowing scores of some transition zone (TZ) lesions to be increased. Literature on the clinical impact of these rules is scarce. Findings For TZ lesions upgraded with DWI: "2 + 1" lesions show a cancer detection rate (CDR) of 13%, and "3 + 1" lesions show a CDR of 37%. Clinical relevance Upgraded TZ lesions may impact individualized biopsy-decisions, especially as "3 + 1" lesions harbor significant disease in 2-out-of-5 patients. Still, the high rate of grade group = 1 and benign findings in these sub-categories emphasizes the need for strategies to minimize overdiagnosis.

Keywords: Clinically significant prostate cancer (csPCa); Diffusion-weighted imaging; Magnetic imaging resonance (MRI); Prostate neoplasm; Transition zone.

Fig. 1

Schematic diagram shows the PI-RADS v2.1 upgrade rules for transition zone lesions and PI-RADS categories

Fig. 2

Flow diagram illustrating the systematic process of study selection, screening, eligibility assessment, and final inclusion of studies on the meta-analysis (PRISMA)

Fig. 3

a, b Cancer detection rates (CDR) for GG = 1, GG ≥ 2, benign TZ lesions with their corresponding 95% confidence intervals and trend lines for (a) PIRADS 1-5, (b) PI-RADS 1-5 with categories “2 + 1” and “3 + 1” separated

Fig. 4

a–d Forest Plots for Odds Ratios of (a) PIRADS 2 + 1 vs. 2, (b) 3 + 1 vs. 3, (c) 2 + 1 vs. 3, (d) 3 + 1 vs. 4 in predicting GG ≥ 2

Fig. 5

Diagnostic accuracy with Prostate Imaging Reporting and Data System (PI-RADS) greater than or equal to 2 + 1 considered positive and GG ≥ 2 as the outcome. Summary receiver operating characteristic (SROC) curve shows diagnostic accuracy at the lesion level (area under the SROC curve, 0.86(95% CI: 0.82–0.90) and corresponding forest plots show sensitivity and specificity, with 94% (95% CI: 90%–97%) and 31% (95% CI: 20%–45%), respectively