Risk stratification of men choosing surveillance for low risk prostate cancer

Abstract

Purpose: We sought to predict biopsy progression in men on prostate cancer surveillance.

Materials and methods: A total of 376 men with a median age of 65.5 years (range 45.8 to 79.5) with low risk prostate cancer on surveillance underwent at least 1 followup biopsy after diagnosis. Progression was defined at surveillance biopsy as Gleason pattern 4 or 5, greater than 2 biopsy cores with cancer or greater than 50% involvement of any core with cancer. Proportional hazards analysis was used to evaluate the association between covariates and progression at surveillance biopsy. The Kaplan-Meier method was used to estimate the probability of disease progression.

Results: Of the 376 men 123 (32.7%) had progression a median of 5.6 years (range 0.3 to 8.5) after diagnosis. Percent free PSA and maximum percent core involvement at diagnosis were associated with progression, allowing stratification of the progression risk at initial surveillance biopsy. Cancer presence and PSA density at initial surveillance biopsy were associated with subsequent progression, allowing stratification of the cumulative incidence of progression 3 years after initial surveillance biopsy (cumulative incidence 11.1%, 95% CI 4.7 to 25.2 for negative biopsy and PSAD less than 0.08 ng/ml/cm(3) vs 53.6%, 95% CI 38.6 to 70.0 for positive biopsy and PSAD 0.08 ng/ml/cm(3) or greater, log rank test p <0.0001).

Conclusions: Clinical variables at diagnosis and at first surveillance biopsy during followup in an active surveillance program can be used to inform men about the likelihood of an unfavorable prostate biopsy. This information could improve patient and physician acceptance of active surveillance in carefully selected men.

Figure 1

Cumulative incidence of unfavorable biopsy

Figure 2

Unfavorable biopsy unadjusted Kaplan-Meier cumulative event curves in patients at low—low PSAD (less than 0.08 ng/ml/cm³) plus negative biopsy (dashed curve), intermediate—high PSAD or positive biopsy (solid gray curve) and high—high PSAD (0.08 ng/ml/cm³ or greater) plus positive biopsy (solid black curve) risk based on biopsy results and PSAD at initial surveillance visit (high vs intermediate vs low risk log rank test p <0.0001).

Figure 3

Cumulative incidence of unfavorable biopsy (progression) (white boxes) at initial surveillance biopsy based on percent fPSA (greater than 15% vs 15% or less) and maximum percent core involvement with cancer (less than 35% vs 35% or greater) at diagnosis. n, total number of events at any time during followup in total number of patients at start of followup. Values in parentheses represent 95% CI.

Figure 4

Cumulative incidence of unfavorable biopsy (progression) (gray boxes) 3 years after initial surveillance biopsy in men without unfavorable biopsy at initial surveillance biopsy was based on initial surveillance biopsy results (negative vs positive for cancer if favorable pathological findings) and PSAD (less than 0.08 vs 0.08 ng/ml/cm³ or greater). n, total number of events at any time during followup in total number of patients at start of followup. Values in parentheses represent 95% CI.