Comparison of Pathological Outcomes for Men with Low Risk Prostate Cancer from Diverse Practice Settings: Similar Results from Immediate Prostatectomy or Initial Surveillance with Delayed Prostatectomy

Abstract

Purpose: We compared pathological outcomes after radical prostatectomy for a population based sample of men with low risk prostate cancer initially on active surveillance and undergoing delayed prostatectomy vs those treated with immediate surgery in order to better understand this expectant management approach outside of the context of academic cohorts. We hypothesized that delays in surgery due to initial surveillance would not impact surgical pathological outcomes.

Materials and methods: We performed a prospective cohort study of 2 groups of patients with NCCN low risk prostate cancer from practices in the Michigan Urological Surgery Improvement Collaborative, that is 1) men who chose initial active surveillance and went on to delayed prostatectomy and 2) men who chose immediate prostatectomy. Diagnoses occurred from January 2011 through August 2015. For these 2 groups we compared radical prostatectomy Gleason scores, and rates of extraprostatic disease, positive surgical margins, seminal vesicle invasion and lymph node metastases.

Results: During a median followup of 506 days 79 (6%) of 1,359 low risk men choosing initial surveillance transitioned to prostatectomy. Compared to those treated with immediate prostatectomy (778), men undergoing delayed surgery were more likely to have Gleason score 7 or greater disease (69.2% vs 48.8%, respectively, p=0.004), but were no more likely to have positive margins, extraprostatic extension, seminal vesicle invasion or lymph node metastases.

Conclusions: Patients with low risk prostate cancer who enter active surveillance have higher grade disease at prostatectomy compared to those undergoing immediate surgery. However, the lack of difference in other adverse pathological outcomes suggests preservation of the window of curability.

Keywords: neoplasms; prostate; prostatic neoplasms; treatment outcome; watchful waiting.

Figure 1. Reasons for transition to radical prostatectomy (RP) among men initially entering active surveillance (AS)

(PSA – prostate specific antigen; MRI – magnetic resonance imaging) All increases in Gleason grade or tumor volume were determined on follow-up surveillance biopsy

Figure 2. Comparison of pathological Gleason score for NCCN low-risk patients undergoing immediate RP versus initial AS with delayed RP (n=778 for immediate RP and 79 for initial AS)

Patients with missing data excluded for percentage calculations

Figure 3. Comparison of adverse pathologic parameters for NCCN low-risk patients undergoing immediate RP versus initial AS with delayed RP (n=778 for immediate RP and 79 for initial AS)

Patients with missing data excluded for percentage calculations

Figure 4. Comparison of pathological Gleason score for NCCN very low-risk patients undergoing immediate RP versus initial AS with delayed RP (n=192 for immediate RP and 30 for initial AS)

Patients with missing data excluded for percentage calculations

Figure 5. Comparison of adverse pathologic parameters for NCCN very low-risk patients undergoing immediate RP versus initial AS with delayed RP (n=192 for immediate RP and 30 for initial AS)

Patients with missing data excluded for percentage calculations