Now that Dendreon (NASDAQ:DNDN) has delivered favorable results for its experimental prostate cancer treatment, Provenge, and as much as seven-bagger results for recent investors, those investors looking for the next big thing in prostate cancer treatment will undoubtedly ask: What's next?

There are plenty of choices. Prospects include drugs approved for other types of cancer, such as Sutent (kidney and gastrointestinal) from Pfizer (NYSE:PFE) and Sprycel (leukemia) from Bristol-Myers Squibb (NYSE:BMY), as well as new compounds from small and large companies. The research also includes non-cancer drugs like GlaxoSmithKline's (NYSE:GSK) Avodart, which is currently used for treating the benign swelling of the prostate.

Sprycel is being tested against prostate cancer in combination with Taxotere (from sanofi-aventis (NYSE:SNY)) and the steroid prednisone. Pfizer's Sutent is being tested with just prednisone. Roche's Avastin, currently used for colorectal, breast, and lung cancers, is also being tested.

However, there's a lot of heartache in prostate cancer research. For instance, last year, Cell Genesys stopped two phase 3 trials for Gvax, an experimental immunotherapy prostate cancer treatment. Dendreon also saw its share of heartache when the Food and Drug Administration turned down the company's original application for Provenge.

More choices
Dendreon expects to file a revised application with the FDA during the fourth quarter, and the agency will probably issue a verdict next year. That means that Provenge would likely be the next major prostate cancer treatment available.

If approved, Provenge would compete with Taxotere for treating prostate cancer that has metastasized and no longer responds to the many hormone therapy drugs on the market. Hormone therapy decreases the body's production of testosterone or blocks the prostate cancer cell's ability to use it.

Taxotere plus prednisone had an extended median survival of 2.5 extra months compared to men taking prednisone with another drug, mitoxantrone, but it has significant side effects. For comparison, Provenge had a median 4.1 extra months of survival versus those receiving a placebo, with fewer severe side effects.

Investors beware, however! Because Provenge and Taxotere haven't been tested side-by-side yet, comparing survival benefits based on those clinical trials is iffy.

A different approach
Provenge doesn't prevent the disease, unfortunately. Instead, it uses the body's defense system to fight the cancer. Dendreon harvests certain cells from a patient's blood, fortifies them to provide a better defense against prostate cancer cells, and then infuses them back into the body.

The lure of immunotherapies like Provenge lies not only in their effectiveness, if Provenge is typical, but also in their relative convenience and side effect profile versus traditional cancer drugs.

Investing in the next treatment
The prostate cancer research story outlines the dilemma for investors who must decide not only what science looks best but how much risk they are willing to tolerate.

A long-term Dendreon shareholder would have had to be a true believer, have the patience of Job, or be the world's greatest market timer. In the nearly nine years since Dendreon went public, shares have bounced from the mid-$20s to bus fare, with many dramatic swings.

For more cautious investors, a company like Pfizer or Bristol-Myers Squibb might be the safer choice. A failed prostate cancer clinical trial for Sutent or Sprycel would have limited downside because those drugs treat other cancers and the companies have other revenue sources. The upside of a successful clinical trial is the adding of potentially significant sales.

There's no easy formula here. Investing in cancer therapies requires patience -- or the ability to guess which small biotech will come out with the latest hot news.

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Fool contributor Robert Steyer doesn't own shares of any companies cited in this article. Glaxo is a former Income Investor recommendation. Pfizer is an Inside Value pick. The Motley Fool has a disclosure policy.