Introduction:

Active surveillance (AS) is an accepted management strategy for very low risk, low risk, and select cases of favorable intermediate risk localized prostate cancer (PCa). Long term data, especially in intermediate risk, are critical for understanding which patients are suitable for this strategy and who should transition to treatment. We investigated our AS cohort to evaluate outcomes stratified by AUA risk groups with a focus on favorable intermediate risk.

Methods:

We reviewed our institutional database of men enrolled in AS for localized PCa from 1996-2016. Our AS protocol includes prostate specific antigen (PSA) and digital rectal exam (DRE) every 4-6 months for 3 years, then annually if stable. Mandatory confirmatory 12 core biopsy is done at 12-18 months and since 2014, multiparametric magnetic resonance imaging (mpMRI) and MRI-fusion biopsy have become integral at confirmatory biopsy. Additional imaging and/or biopsies are done at the discretion of physician and patient. We evaluated freedom from treatment (FFT), treatment type and indication, biochemical recurrence (BCR), and freedom from metastasis (FFM). Survival analyses were conducted using the Kaplan-Meier method; comparisons between risk group outcomes were done with the Wilcoxon rank sum test. 

Results:

The cohort consisted of 1272 men (see Table 1). Unfavorable risk men were excluded from this analysis. Median follow-up time was 6.4 years (IQR 0.9-11.9). 1232 men (96.8%) had Grade Group (GG) 1, 39 (3.1%) had GG 2, and one had GG 3. For the favorable intermediate risk group, 100 (76.9%) were included due to PSA>10, 28 (21.5%) due to GG 2, and 2 (1.54%) due to cT2 disease. There was no statistically significant difference in the proportion of men progressing to treatment between risk groups (p = .24). Of those treated, compared to very low and low risk, the favorable intermediate risk group had a significantly larger proportion of men receiving external beam radiotherapy (p < .001) and a significantly smaller proportion of men receiving radical prostatectomy (p = .01). For very low, low, and favorable intermediate risk groups, respectively: 5 year FFT was 71.1%, 64.4%, and 65.7%; 10 year FFT was 56.9%, 55.1%, and 53.7%; 5 year BCR-free survival was 99.1%, 98.5%, 96.5%; 10 year BCR-free survival was 97.9%, 96.9%, 94.5%; 5 year FFM was 99.8%, 99.0%, and 100%; 10 year FFM was 98.2%, 95.4%, and 91.3%. There were no statistically significant differences in FFT (p = .10), BCR (p = .56), or FFM (p = .38) between risk groups. Within the favorable intermediate risk group, there were no statistically significant differences in FFT (p = .70) or FFM (p = .36) between men with GG 2 and those with PSA>10.

Conclusion:

Our results suggest that carefully selected men with favorable intermediate risk PCa may be reasonable candidates for active surveillance, demonstrating no statistically significant difference in freedom from treatment, biochemical recurrence, or metastasis from that of very low and low risk men. AS remains a safe and viable option for men of all three risk groups with a 96.4% 10 year metastasis-free survival at our institution. Further study of the ideal inclusion criteria, surveillance strategy, triggers for intervention, and the role of advanced imaging and biomarkers is needed in this population.  

Funding: N/A