CHICAGO -- The U.S. Food and Drug Administration has all the data it needs now to finally approve Dendreon's ( DNDN) prostate cancer vaccine Provenge, says the researcher who presented the Provenge study results Tuesday. "These data answer all the questions raised two years ago by the FDA. I think they will approve it," said Dr. David Penson, a professor of urology at the University of Southern California and an investigator in the Provenge study. The FDA refused to approve Provenge two years ago despite data from previous clinical trials showing the drug extended survival by 4.3 months in men with advanced prostate cancer. At that time, regulators asked Dendreon to provide more proof that Provenge could prolong survival. That proof came Tuesday at the annual meeting of the American Urological Association. Penson presented the final data from Dendreon's phase III IMPACT study showing that Provenge prolonged survival by 4.1 months in men with advanced prostate cancer. After three years, 31.7% of Provenge-treated patients were alive, compared to 23% for control patients -- a 38% improvement. The results were statistically significant.