Biotech cancer fighter Dendreon (NASDAQ:DNDN) is one of the day's hot stories, with the stock up nearly 30% on massive volume. Driving the move was the announcement that subjects in the Phase III trial of Provenge demonstrated a "significant survival advantage" in patients with prostate cancer.

Investors were right to cheer today: Provenge, a University of Washington doctor said in Dendreon's press release, "has the potential to change the way we treat prostate cancer in the future." Though a range of treatments is available, according to the National Prostate Cancer Coalition, there is also an ample supply of patients: Some 220,000 new cases are diagnosed each year. The disease is the most common cancer among American men.

David Nierengarten discussed Dendreon in September, looking also at Geron (NASDAQ:GERN), Cell Genesys (NASDAQ:CEGE), and Genzyme (NASDAQ:GENZ) as part of a broader discussion of companies looking to develop cancer vaccines. At the time, he highlighted Dendreon for its strong balance sheet, product pipeline, and development partnership with Genentech (NYSE:DNA).

Phase III trials are the big ones for any company that wants to sell a drug in the U.S. (Our Five Steps of Drug Development feature is a handy reference on this topic.) It's the final and most involved stage of a lengthy human testing process, and looks to determine not only the effectiveness of the treatment but also its potential side effects over time. Provenge, today's news indicates, scores favorably on both counts.

Next up is Food and Drug Administration approval, after which a drug can hit the market. At that point Dendreon, should things go its way, might really stand to reward investors who, despite today's pop, have watched the stock seesaw (and just barely outpace the S&P 500) since the company went public in mid-2000.

Share your thoughts on Provenge on our Dendreon discussion board. Dave Marino-Nachison can be reached at dmarnach@fool.com.