Does the Visibility of Grade Group 1 Prostate Cancer on Baseline Multiparametric Magnetic Resonance Imaging Impact Clinical Outcomes?
This retrospective, HIPAA (Health Insurance Portability and Accountability Act) compliant, single center study was approved by our institutional review board with an informed consent waiver. From 2006 to 2018, 4,862 patients underwent mpMRI at our institution. To identify patients with maximum GG1 on mpMRI informed biopsy, we used the inclusion criteria of 1) GG1 on systematic biopsy less than 12 months prior to or after baseline mpMRI in the absence of mpMRI visible lesions, 2) GG1 on MRI targeted biopsy (with or without additional systematic biopsy) less than 12 months after baseline mpMRI in men with mpMRI visible lesions, and 3) minimum followup of more than 3 months. Patients were excluded from study for prior diagnosis of GG greater than 1 PCa, history of PCa treatment and incomplete clinical baseline parameters, leaving 454 patients for analysis.
At our institution any man with GG1 PCa can be suitable for AS at the discretion of the treating physician. The standard monitoring protocol includes PSA and digital rectal examinations every 6 to 12 months and re-biopsy every 1 to 3 years depending on PSA dynamics and digital rectal examination findings. Serial mpMRI as an additional monitoring tool is not used according to a fixed protocol. Rather, mpMRI is ordered to either help decide whether to proceed with biopsy when write my paper parameters are suggestive but not outright indicative for repeat biopsy, or to help identify possible targets when a followup biopsy was already planned on clinical grounds.
Multiparametric Magnetic Resonance Imaging
The mpMRI protocol consisted of T2-weighted imaging, diffusion weighted imaging with apparent diffusion coefficient maps and dynamic contrast enhanced imaging. Different devices and imaging parameters were used between 2006 and 2018 with mostly endorectal coil at 1.5T until 2012 and no endorectal coil thereafter at 3T. All mpMRI findings were interpreted prospectively by fellowship trained institutional radiologists. MpMRI after 2016 was graded and performed according to the standardized Prostate Imaging Reporting and Data System version 2 (PI-RADS®v2) system. Prior to the publication of these guidelines, mpMRIs were graded according to 5-point Likert scales. Results were categorized as negative (2/5 or less), equivocal (3/5) or positive (4/5 or greater), indicating the level of conspicuity and suspicion for csPCa.
Prostate Biopsies and Histopathological Evaluation
Data acquisition and reporting were consistent with the Standards of Reporting for MRI targeted biopsy Studies (START) guidelines. Baseline and followup biopsies included MRI-TRUS fusion and/or 12-core systematic TRUS guided biopsies. For all lesions less than 1 cm TRUS fusion was performed using the Artemis (Eigen) system. The option of cognitive fusion for larger lesions was used if the clinician believed the target could be easily sampled. This paper writing service was consistent during the study period. Biopsy cores were reported according to the standards of the International Society of Urological Pathology (ISUP) at the time biopsy was performed.
The primary study outcome was definitive TFS (including RP or radiation therapy). Secondary outcomes were upgrade to GG2 or greater on followup biopsy and unfavorable disease at RP, defined as pT stage 3-4 and/or GG3 or greater. Outcomes were assessed using Kaplan-Meier analysis and the log rank test was used to assess differences between groups. Baseline time point for analyses was the time of the mpMRI scan. Followup was calculated using the reverse Kaplan-Meier method. The association of baseline variables with primary and secondary outcomes was assessed by multivariable Cox proportional hazard regression (or an adaptation with Firth’s penalized likelihood) including the variables of results from baseline mpMRI, year of baseline mpMRI, age at baseline mpMRI, PSAd, percent of positive cores and maximum percent involvement of a core. Distributional differences of study variables between groups of mpMRI results were compared using the chi-square test for categorical variables, and parametric or nonparametric (Kruskal-Wallis test) ANOVA for continuous variables. In case of significant differences from the 3-group comparison additional pairwise comparisons were performed. All statistical tests were 2-tailed and p <0.05 was considered statistically significant. Statistical analyses were performed using R version 3.6.1 (R Foundation for Statistical Computing, Vienna, Austria).