Serial Anatomical Prostate Ultrasound during Prostate Cancer Active Surveillance

Purpose: The growth potential of low grade prostate cancer is unknown and yet it is potentially impactful for the practice of active surveillance. We evaluated the incidence, growth dynamics and clinical significance of changes in prostate lesions on serial transrectal ultrasound among a large cohort of men with prostate cancer managed by active surveillance.

Materials and methods: This retrospective study included men with prostate cancer treated with active surveillance at UCSF (University of California-San Francisco) from 2000 to 2014 who underwent a minimum of 2 transrectal ultrasound studies. Study inclusion criteria were prostate specific antigen 20 ng/ml or less, clinical stage T2 or less and biopsy Gleason grade 3 + 4 or less. Progression end points included an increase in imaging stage, a 50% or greater increase in volume and an increase in the number of sites (sextants) with apparent lesions. The relationship between transrectal ultrasound progression and biopsy Gleason upgrade was assessed by univariate and multivariate logistic regression models.

Results: The 875 identified patients underwent a median of 5 transrectal ultrasound studies (IQR 3-8). Median followup was 49 months (IQR 27-81). Of the patients 345 (39%) progressed on serial transrectal ultrasound, including 51 by size, 265 by the number of lesion sites and 279 by stage. Median time to progression was 14 months. Transrectal ultrasound progression was independently associated with biopsy upgrade (OR 1.8, 95% CI 1.3-2.5, p <0.01).

Conclusions: Local progression on transrectal ultrasound was associated with Gleason upgrade at biopsy. These results suggest that stable imaging findings on transrectal ultrasound may allow for increased intervals between biopsies among men on active surveillance. A prospective study is required to evaluate the usefulness of such a practice.