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

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.