Active surveillance in favorable intermediate risk prostate cancer: outstanding questions and controversies

MRI at diagnostic versus confirmatory biopsy during MRI-based active surveillance of prostate cancer

OBJECTIVES

Active surveillance (AS) is a management strategy for patients with favorable risk prostate cancer. Multi-parametric magnetic resonance imaging (mpMRI) may impact upgrading rates, but there is mixed evidence on the appropriate timing to introduce mpMRI. We evaluated timing of initial mpMRI use for patients on AS and compared upgrading and intervention rates for AS candidates who received initial mpMRI before diagnostic biopsy vs. confirmatory biopsy.

SUBJECTS AND METHODS

Patients enrolled in AS captured by the Prospective Loyola Urology mpMRI (PLUM) Prostate Biopsy Cohort which captures men undergoing MRI-fusion prostate biopsy. We included patients enrolled in AS between January 2014 and October 2022. We conducted a retrospective analysis of patients who underwent MRI-fusion prostate biopsy while on AS at our institution. The cohort was stratified by men who underwent first mpMRI prior to diagnostic biopsy (MRI-DBx), confirmatory biopsy (MRI-CBx), or a subsequent surveillance biopsy. Oncologic outcomes including pathologic reclassification, intervention-free survival, progression-free survival, and overall survival were evaluated.

RESULTS

Of 346 patients identified on AS, 94 (27.2%) received mpMRI at the time of diagnostic biopsy, 182 (52.6%) at confirmatory biopsy, and 70 (20.2%) at a later biopsy. At confirmatory biopsy (median 14 months), there was no difference in upgrading (HR 0.95, P = 0.78) or intervention rates (HR 0.97, P = 0.88) between MRI-DBx and MRI-CBx. PI-RADS score on initial mpMRI was associated with upgrading during AS follow-up relative to men with negative mpMRI (HR 4.20 (P = 0.04), 3.24 (P < 0.001), and 1.99 (P < 0.001) for PI-RADS 5, 4, and 3, respectively), and PSA density was associated with intervention (HR 1.52, P = 0.03).

CONCLUSION

mpMRI can serve as a prognostic tool to select and monitor AS patients, but there was no difference in upgrading or intervention rates based on initial timing of MRI.

Active surveillance selection and 3-year durability in intermediate-risk prostate cancer following genomic testing

BACKGROUND

Genomic testing can add risk stratification information to clinicopathological features in prostate cancer, aiding in shared medical decision-making between the clinician and patient regarding whether active surveillance (AS) or definitive treatment (DT) is most appropriate. Here we examined initial AS selection and 3-year AS durability in patients diagnosed with localized intermediate-risk prostate cancer who underwent Prolaris testing before treatment decision-making.

METHODS

This retrospective observational cohort study included 3208 patients from 10 study sites who underwent Prolaris testing at diagnosis from September 2015 to December 2018. Prolaris utilizes a combined clinical cell cycle risk score calculated at diagnostic biopsy to stratify patients by the Prolaris AS threshold (below threshold, patient recommended to AS or above threshold, patient recommended to DT). AS selection rates and 3-year AS durability were compared in patients recommended to AS or DT by Prolaris testing. Univariable and multivariable logistic regression models and Cox proportional hazard models were used with molecular and clinical variables as predictors of initial treatment decision and AS durability, respectively.

RESULTS

AS selection was ~2 times higher in patients recommended to AS by Prolaris testing than in those recommended to DT (p < 0.0001). Three-year AS durability was ~1.5 times higher in patients recommended to AS by Prolaris testing than in those recommended to DT (p < 0.0001). Prolaris treatment recommendation remained a statistically significant predictor of initial AS selection and AS durability after accounting for CAPRA or Gleason scores.

CONCLUSIONS

Prolaris added significant information to clinical risk stratification to aid in treatment decision making. Intermediate-risk prostate cancer patients who were recommended to AS by Prolaris were more likely to initially pursue AS and were more likely to remain on AS at 3 years post-diagnosis than patients recommended to DT.

Inference of core needle biopsy whole slide images requiring definitive therapy for prostate cancer

BACKGROUND

Prostate cancer is often a slowly progressive indolent disease. Unnecessary treatments from overdiagnosis are a significant concern, particularly low-grade disease. Active surveillance has being considered as a risk management strategy to avoid potential side effects by unnecessary radical treatment. In 2016, American Society of Clinical Oncology (ASCO) endorsed the Cancer Care Ontario (CCO) Clinical Practice Guideline on active surveillance for the management of localized prostate cancer.

METHODS

Based on this guideline, we developed a deep learning model to classify prostate adenocarcinoma into indolent (applicable for active surveillance) and aggressive (necessary for definitive therapy) on core needle biopsy whole slide images (WSIs). In this study, we trained deep learning models using a combination of transfer, weakly supervised, and fully supervised learning approaches using a dataset of core needle biopsy WSIs (n=1300). In addition, we performed an inter-rater reliability evaluation on the WSI classification.

RESULTS

We evaluated the models on a test set (n=645), achieving ROC-AUCs of 0.846 for indolent and 0.980 for aggressive. The inter-rater reliability evaluation showed s-scores in the range of 0.10 to 0.95, with the lowest being on the WSIs with both indolent and aggressive classification by the model, and the highest on benign WSIs.

CONCLUSION

The results demonstrate the promising potential of deployment in a practical prostate adenocarcinoma histopathological diagnostic workflow system.