#0500

The Effect of Prostate MRI on NCCN prostate cancer risk stratification

P. Stapleton¹, T. Milton¹, N. Sathianathen², M. O'Callaghan³

¹Royal Adelaide Hospital, Department of Surgery, Adelaide, Australia
²Grampians Health Ballarat, Department of Surgery, Ballarat, Australia
³Flinders Medical Centre, Department of Surgery, Adelaide, Australia

Introduction:

A multiparametric MRI of the prostate prior to prostate biopsy allows a targeted biopsy and more accurate pathology results. A more accurate representation of the true pathology allows better prostate cancer risk stratification and guidance of further management. The objective of this study was to determine if patients who had an MRI prostate prior to biopsy had a more accurate NCCN prostate cancer risk stratification.

Material and methods:

We conducted a retrospective audit of 2994 men with non-metastatic prostate cancer diagnosed between 2010 and 2019 who progressed to a radical prostatectomy within 1 year of diagnosis without alternative cancer treatment from the multi-institutional South Australia Prostate Cancer Clinical Outcomes Collaborative registry. The study compared the NCCN risk stratification prior and after having a radical prostatectomy and compared the varying rates of upgrading and downgrading for patients with and without a pre-biopsy MRI. Data were also obtained on suspected confounding variables; age, PSA, time to RP, T-stage at diagnosis and RP, number of cores, number of positive cores, prostate size, tumour volume and procedure type. The results were assessed through cross tabulation and uni- and multi-variable logistic regression while adjusting for confounders.

Results:

NCCN risk stratification was calculated for all patients with available data (n = 1867). Risk stratification upgrading occurred in 57.3% (1070/1867) of patients, downgrading 6.3% (118/1867) and congruent risk stratification in 36.4% (679/1867). For patients who had an MRI prior to biopsy, the NCCN risk stratification score was upgraded 62.5% of the time compared to 67.2% for those without. The inclusion of a pre-biopsy MRI demonstrated a statically significant decrease in NCCN risk stratification in univariable analysis (p = 0.049, OR 0.82, CI 0.64–1.01). However, when adjusted for confounders, the use of an MRI did not maintain a statistical significance.