RECURRENCE PATTERNS AFTER RADICAL RETROPUBIC PROSTATECTOMY - CLINICALUSEFULNESS OF PROSTATE-SPECIFIC ANTIGEN DOUBLING TIMES AND LOG SLOPE PROSTATE-SPECIFIC ANTIGEN

Purpose: We studied the correlation between prostate specific antigen (PSA) doubling time or, equivalently, log slope PSA and clinical recur rence in patients with detectable PSA after radical retropubic prostat ectomy who were followed expectantly. Materials and Methods: In patien ts with PSA recurrence after radical retropubic prostatectomy log slop e PSA was determined from the difference in the 2 log PSA values divid ed by the time between readings in months. For a given slope the corre sponding PSA doubling time was calculated as log x 2 divided by the sl ope of the log PSA line. When the initial PSA value was considerably g reater than 0.4 ng./ml., the log slope PSA plot was extrapolated to de termine the time point at which PSA would have become detectable (0.4 ng./ml.). The relationship between these values, and the time and patt ern of clinical recurrence were studied. Results: In this series of 77 patients 80% with PSA doubling time of 6 months or greater remained c linically disease-free compared to 64% with PSA doubling time less tha n 6 months. PSA doubling time had better correlation with time to clin ical recurrence after PSA became detectable (p <0.001 Cox proportional hazards model) than Gleason sum, pathological stage or margin status. Biochemical recurrence within 3 months was associated with early clin ical recurrence (p <0.002). In addition, short PSA doubling time, that is a high log slope, regardless of the time at which PSA became posit ive was strongly associated with clinical recurrence (p <0.001). Dista nt recurrence was invariably associated with short PSA doubling time. Conversely, local recurrence reliably correlated with long PSA doublin g time, that is a low log slope. Conclusions: After PSA became detecta ble PSA doubling time or, equivalently, log slope PSA, was a better in dicator of the risk and time to clinical recurrence after radical retr opubic prostatectomy than preoperative PSA, specimen Gleason sum or pa thological stage. Hormone treatment may be targeted to patients at hig h risk for early metastatic clinical recurrence, appropriately timed r adiation can be offered for proved local recurrence in those with long PSA doubling time and expectant treatment may be proposed for those w ith long PSA doubling time who remain clinically disease-free. Frequen t and expensive imaging does not appear to be cost-effective in this l atter group.