Purpose: Men with low risk prostate cancer on active surveillance undergo multiple biopsies over time. The long-term clinical significance of consecutively negative biopsies is not known.
Materials and methods: Men with low risk prostate cancer prospectively enrolled in an active surveillance database with at least 4 biopsies were included in the study. Exposure variables were 0, 1 or 2 consecutively negative biopsies after diagnosis. Other variables included age, prostate specific antigen, prostate specific antigen density, Gleason grade group, percent positive cores and magnetic resonance imaging findings. Outcome variables were the detection of any cancer at fourth biopsy and active treatment.
Results: A total of 514 men were included, with 112 (22%) men having 1 negative biopsy and 78 (15%) with 2 consecutively negative biopsies. Median prostate specific antigen density was lower for men with 1 negative biopsy (0.11) and consecutively negative biopsies (0.10) compared to men who never had a negative biopsy (0.13, p <0.01). On univariable logistic regression higher prostate specific antigen density (OR 1.68, 95% CI 1.16-2.45) and suspicious magnetic resonance imaging lesions (OR 2.00, 95% CI 1.16-3.42) were associated with a higher likelihood of detecting cancer on fourth biopsy. On multivariable logistic regression 1 negative biopsy (OR 0.22, 95% CI 0.12-0.41) and consecutively negative biopsies (OR 0.12, 95% CI 0.06-0.24) were associated with a lower likelihood of detecting cancer at outcome biopsy. Unadjusted 10-year treatment-free survival was highest for patients with consecutively negative biopsies (84%) and 1 negative biopsy (74%) than those who had none (66%) (log rank p=0.02).
Conclusions: Consecutively negative surveillance biopsies are correlated with favorable clinical risk factors and independently associated with subsequent negative biopsy and lower risk of active treatment.
Keywords: biopsy; health care; multiparametric magnetic resonance imaging; outcome assessment; prostatic neoplasms; watchful waiting.