In the United States, prostate cancer is now the most common type of malignancy detected in men. Even more concerning is that prostate cancer has crept up to the second-leading cause of cancer-specific deaths among men in the U.S., according to recently released statistics from the American Cancer Society -- although it lags behind lung, liver, stomach, colorectal, and oesophageal cancer globally.

Prostate cancer cases have also been increasing markedly since the 1970s, although this trend could be a statistical artifact from a concomitant increase in screening rates. Put simply, more men began getting screened in the 1990s, potentially leading to a higher detection rate. Indeed, incidence rates are known to be significantly higher in Western countries, where regular screenings are common, compared to developing nations.

What's important to understand from an investing perspective is that the global prostate cancer market is presently valued at over $26 billion, and this figure is expected to rise to over $50 billion as soon as 2017. Consequently, we have seen several new prostate cancer drugs hit the market over the past four years, with dozens of others entering clinical trials. So let's take a deeper look at five biotechs leading this wave of new innovation.  

New generation of commercially available therapeutics
Johnson & Johnson's (JNJ -0.31%) hormome therapy Zytiga, developed by its subsidiary Janssen Biotech, was approved by the U.S. Food and Drug Administration, or FDA, in 2011. Zytiga is indicated as a treatment for castration-resistant metastatic prostate cancer and works by blocking androgen production -- a common therapeutic target among prostate cancer hormone therapies in general.  Zytiga is now a market leader among prostate cancer drugs, raking in $1.7 billion in sales in 2013. That said, Medivation and Astellas Pharma's hormone therapy Xtandi, approved in 2012, appears to be cutting into Zytiga's double-digit sales growth. Time will tell how this head to head competition plays out. 

Source: Prostate.net. 

Dendreon's (NASDAQ: DNDN) personalized prostate cancer vaccine Provenge became commercially available in 2010 for the treatment of asymptomatic or minimally symptomatic, castration-resistant metastatic prostate cancer. The drug has struggled to gain market share, and sales have been particularly rocky since the approvals of Xtandi and Zytiga. On the bright side, Dendreon will launch Provenge in Europe this year, which could help boost sales.

Source: urosciences.com

In 2013, the FDA approved Bayer Pharmaceuticals' (BAYR.Y 1.93%) radium isotope Xofigo as a treatment for men with prostate cancer that has spread to their bones and have stopped responding to hormone therapy. Clinical studies showed that Xofigo extended life span by three months on average, but some countries have balked at covering the drug because of its considerable cost. As a more specialized drug, Xofigo probably won't see the eye-popping sales numbers of Zytiga, but the drug could be a decent revenue earner in its own right due to the sheer size of the prostate cancer market. 

Clinical products to watch
On the clinical front, there are several promising therapies under development. For instance, the DNA-based vaccine-maker Inovio Pharmaceuticals (INO 4.39%) is developing a prostate cancer vaccine dubbed "INO-5150," currently at the preclinical stage of development. INO-5150 is another immunotherapy approach, but the biological mechanism is entirely different from Provenge.

Seattle Genetics (SGEN) is teaming up with Progenics Pharmaceuticals, among others, to develop antibody drug conjugates, or ADCs, to treat prostate cancer. Seattle Genetics has both an early and mid-stage ADC under development for prostate cancer. The mid-stage candidate has faced some setbacks because of toxicity issues, which may hinder further development. Overall, it's important to bear in mind that this is only a small sampling of the clinical candidates for prostate cancer.

Foolish wrap-up
Prostate cancer has become an epidemic for men in the U.S., and the new generation of therapies could radically change the standard of care for this disease. Currently, Zytiga is locked in a fierce battle with Xtandi for the front-runner position, but Provenge has also seen sales grow modestly recently. In my view, this dynamic market shows that doctors are experimenting with their new found options, keeping any one drug from gaining a stranglehold on the market. Looking ahead, the continued growth of the prostate cancer market suggests there is ample room for even more new therapies. As such, you may want to dig deeper into these five biotechs helping to fight the battle against prostate cancer. 

Editor's Note: A previous version of this article did not mention that Astellas Pharma is Medivation's partner on the drug Xtandi. The Fool regrets the error.