Not exactly rock solid, but seems to be worth attention:
"They initially identified 857 relevant records, ultimately citing 69 studies in their paper. They point out that most studies were retrospective and therefore subject to selection bias, and that generally the level of evidence was not high.
Nonetheless, they concluded that radical prostatectomy does improve survival in lymph node (LN)-positive prostate cancer. In one study, for example, 10-year survival was 64% in patients who were treated with radical prostatectomy compared to 28% among those in whom the procedure was aborted - albeit that the groups were imbalanced in terms of the number of positive lymph nodes."
www.curetoday.com/index.cfm/fuseaction/news.showNewsArticle/id/13/news_id/3738