Salvage radiotherapy for elevated PSA levels following prostatectomy.

In this issue of The Cancer Journal, Mosbacher et al1 report on the Columbia University experience with salvage radiotherapy (RT) for prostate cancer. All patients had undergone prior radical retropubic prostatectomies (RRPs) and had elevated serum prostate-specific antigen (PSA) levels after surgery This cohort of patients was relatively large, including 72 individuals, with a median follow-up of approximately 4 years. None of the patients had other clinical evidence of prostate cancer except those who had positive prostate bed biopsy results before RT. The major endpoint of this study was biochemical failure after RT; this was defined as (1) two successive PSA rises, (2) a detectable PSA level after levels became undetectable (not specifically defined numerically), or (3) a rise in PSA level leading to salvage hormonal therapy It appears from Figure 1 that most patients failed after salvage RT; the biochemical failure rate was approximately 75% at 4 years and approximately 90% at 5 years. Mosbacher et al1 evaluated the potential prognostic factors associated with biochemical relapse and found that seminal vesicle involvement and Gleason score were negative prognostic factors. Twenty-two patients had prostate bed biopsies before undergoing RT, and the result of the biopsy did not influence the biochemical relapse rate after salvage RT. This is an important finding, suggesting that these patients need not be subjected to prostate bed biopsies before salvage RT. Avoiding biopsies will spare these patients the discomfort and potential risks from this invasive procedure. Additionally, the results of the biopsy can be confusing clinically because although a positive biopsy result is proof of local failure, a negative result does not preclude the presence of local failure. The serum PSA levels decreased after salvage RT in 84% of the patients in the Mosbacher et al1 study. This finding correlates well with our experience. We reported an initial decrease in serum PSA levels after salvage RT in 93% of the patients studied.1 These data suggest that the vast majority (approximately 90%) of these patients have experienced local recurrence. Mosbacher et al1 did not report on other endpoints that may have been of interest to the readers, including overall survival, local failure rates, distant failure rates, and toxicity of therapy The details of the types of diagnostic work-ups performed before salvage radiotherapy were also not included. The biochemical failure rates reported by Mosbacher et al1 following salvage RT appear greater than those of most other published reports, in which 29%–83% of patients were reported to have undetectable PSA levels at last follow-up.2 Mosbacher et al1 critically examined various methods of improving the outcome of salvage RT, which is another important aspect of this paper. There are many potential pitfalls when evaluating and treating patients with elevated PSA levels after prostatectomy First, the diagnostic work-up of these patients should attempt to rule out metastatic disease before RT is administered. We perform a bone scan and diagnostic computed tomography of the pelvis and abdomen in most patients. The ProstaScint scan is useful for identifying patients who have evidence of disease outside the pelvis. The results of the ProstaScint scan have been correlated with the outcome of salvage RT in a report by Kahn et al.3 If the ProstaScint scan showed no evidence of disease outside the pelvis, salvage RT resulted in a 70% biochemical control rate. However, if the ProstaScint scan showed disease outside of the pelvis, the biochemical control rate with salvage RT was reduced to 22%. The ProstaScint scan has an overall accuracy of approximately 62% when it is used to detect disease in patients with elevated PSA levels after RRP, and its usefulness in patients with low-level PSA elevations (e.g.