Prostate cancer topography and tumour conspicuity on multiparametric magnetic resonance imaging: A systematic review and meta-analysis

Introduction The implications of tumour location on mpMRI conspicuity are not fully understood. Identifying topographical correlates that influence conspicuity may improve outcomes. Here, we present the first systematic review and meta-analysis describing the effect of tumour location on prostate cancer conspicuity on mpMRI. Methods Medline, PubMed, EMBASE and Cochrane databases were systematically searched and results were assessed as per the PRISMA statement. Differential tumour conspicuity on mpMRI was compared between cancers in the peripheral zone (PZ), transitional zone (TZ), base, apex, anterior and posterior. Meta-analysis was conducted to compare diagnostic odds ratios (DOR) of mpMRI detection for tumours in the PZ and TZ. PROSPERO registration: CRD42021228087. Results Thematic synthesis showed apical and basal tumours had reduced conspicuity compared to mid-gland tumours. Cancer in the TZ demonstrated increased conspicuity on T2-weighted imaging, whilst PZ cancers had higher conspicuity on diffusion-weighted and dynamic contrast enhancement imaging. mpMRI had better diagnostic accuracy for PZ lesions, albeit higher specificity for TZ lesions. Meta-analysis showed an increased DOR for PZ tumours (OR: 7.206 [95% CI: 4.991;10.403], compared to TZ (OR: 5.310 [95% CI: 3.082; 9.151]). However, the test for subgroup differences was not significant (p = 0.2743). Conclusions Cancer in the apex or base of the prostate may be less conspicuous than mid-gland tumours. Similarly, TZ cancer appears to have reduced conspicuity compared to PZ cancer, however, meta-analysis did not show a significant difference between DOR. Future larger studies with prospective datasets are required to clarify the relationship between tumour position and conspicuity.