Fluctuating prostate-specific antigen levels in patients with initial negative biopsy: should we be reassured?

To evaluate whether the risk of having a positive repeat prostate biopsy is lower in patients with fluctuating prostate-specific antigen (PSA) levels than in patients with a steady or steadily increasing PSA level.

Files were extracted from the 2000-2003 databases of two teaching hospitals; 191 patients who had a first negative biopsy followed by one or more sets of biopsies and at least two PSA measurements were included. A 'fluctuating PSA level' in a patient was defined as a PSA series including at least one PSA value lower than the one immediately preceding it.

The median PSA level at the first biopsy was 7 ng/mL, while that for the second, third and fourth biopsies were 8.0, 8.0 and 8.7 ng/mL, respectively. The median time between the first and second, and the second and third PSA tests was 290 and 317 days, respectively. Prostate cancer was eventually detected in 53 men (27.7%) in whom 39 it was at the first repeat biopsy. Among the 79 patients with a fluctuating PSA level, 17 (22%) had prostate cancer, vs 36 (32%) among the 112 with a 'steady' PSA level; the difference was not significant (P=0.14). When considering the 53 patients diagnosed with prostate cancer, the 17 with a fluctuating PSA level and the 36 others had no significant difference in age, T stage, first PSA level and Gleason score.

In the present study, by contrast with the common and unfounded view, the risk of having a positive repeat prostate biopsy was no lower in men with a fluctuating PSA level than in those with a steady or steadily increasing PSA level. The practical and economical implications warrant further studies to confirm these findings.