Another trial of adjuvant EBRT compared to watchful waiting after RP

A German group has recently published data from another randomized clinical trial of adjuvant external beam radiotherapy (EBRT) in patients shown to have extraprostatic disease after radical prostatectomy (RP), as compared to a “wait and see” or “watchful waiting” strategy.

Wiegel et al. (presumably some time prior to 2004) enrolled 385 men into a randomized, controlled clinical trial to compare RP followed by immediate EBRT with RP alone for patients with pT3No prostate cancer and an undetectable PSA level post-surgery.

Immediately following RP, 192 men were randomly assigned to a wait-and-see policy, and 193 men were assigned to immediate postoperative RT. However, 78/385 patients (20 percent) who did not achieve an undetectable PSA after RP were excluded from treatment. Of the remaining 307 patients, 34 patients on the RT arm did not receive RT and 5 patients on the wait-and-see arm received RT. In total, therefore, 114 patients actually underwent RT and 154 patients were treated with a wait-and-see policy. The primary end point was biochemical progression-free survival.

The results of this study at 5 years of follow-up are as follows:

  • Biochemical progression-free survival in patients with undetectable PSA after RP was significantly improved in the RT group (72 percent) compared to the wait and see group (54 percent).
  • On univariate analysis, Gleason score > 6, Gleason score < 7, PSA level before RP, tumor stage, and positive surgical margins were all independent predictors of outcome.
  • The rate of grade 3 to 4 late adverse effects was 0.3 percent.

The authors conclude that adjuvant RT for patients with pT3No prostate cancer and  postoperatively undetectable PSA significantly reduces the risk of biochemical progression, but also note that further follow-up is needed to assess the effect on metastases-free and overall survival.

The “New” Prostate Cancer InfoLink thinks that it is unfortunate that the authors did not conduct a multivariate analysis of predictors for outcome so that we would know if any one or two of the independent predictors on univariate analysis actually had a dominant effect on outcomes.

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