One of the biggest keys to investing is figuring out which industries or trends will see substantial growth in the future. Fortunately you need not figure out if Google's (NASDAQ:GOOG) Android will beat Apple's iPhone. All you've got to do is look at demographics to find the next growth story.

The baby boomers aren't getting any younger, so we're likely to see the prevalence of cancer rise. That'll be especially true with prostate cancer, which tends to occur later in life.

As one of my biology professors was fond of saying, you've got three choices when it comes to cancer: burn it off (radiation therapy), cut it out (surgery), or poison it (chemotherapy). The treatments have become more high-tech, but the options still fall into those three categories. Let's take a look at all three options and see where investors might benefit.

Burn it off
The use of radiation is a popular option, since it doesn't involve going under the knife. Investors basically have two options: up-and coming-technologies from either smaller companies or larger, more established ones.

Varian Medical Systems (NYSE:VAR) sells a machine that claims to precisely irradiate the tumor while saving the surrounding tissue. Considering what's right next to the prostate, that sounds like a good plan to me. There's also small-cap TomoTherapy (NASDAQ:TOMO), which has a machine that looks like it's straight out of Star Trek. It integrates a CT scanner into the irradiator to more accurately pinpoint the tumor.

Of course, you could get burned if technology passes by the radiation machine. Bypass that risk by buying larger, more diverse companies like General Electric (NYSE:GE) or Siemens (NYSE:SI), both of which sell machines to radiation oncology departments.

Cut it out
Surgery hasn't exactly been the most exciting option for men with prostate cancer, since erectile dysfunction is a potential side effect of a radical prostatectomy.

That was the case until Intuitive Surgical (NASDAQ:ISRG) came out with its daVinci Surgical System. Besides the coolness factor of being operated on by a human-controlled robot, the daVinci offers some real advantages, like significantly less pain and faster recovery to potency and continence. These advantages have helped the procedure become the No. 1 treatment for prostate cancer in the U.S., according to the company.

Intuitive Surgical has developed a wide moat and doesn't have any real immediate threat from competition. Intuitive's only problem is continued expansion. As patients demand the system -- and potentially switch from radiation therapy -- there's potential to grow its own market, but the real key will be how quickly and thoroughly surgeries to operate on kidneys, bladders, and uteruses are adopted.

Poison it
There aren't too many prostate-specific chemotherapy treatments, if any. In fact, there aren't a whole lot of options for patients with a late-stage disease. That's what makes Dendreon's (NASDAQ:DNDN) Provenge so potentially lucrative.

The treatment actually involves convincing the patient's immune system to attack the tumor. This active cellular immunotherapy didn't pass muster when the company took an interim peek at that the data earlier this month, which means investors will have to wait until next year to find out if the FDA is likely to approve the drug. Personally I think that owning the stock right now is a scary proposition, but, if you're looking for a company that's almost completely invested in the prostate cancer space, Dendreon's the company you should own.

Invest in what you know
Unfortunately, almost everyone knows someone that's had prostate cancer, so Peter Lynch's axiom applies to nearly all Fools. With the aging population, now certainly could be the best time to get invested in a treatment space that's sure to grow.

Intuitive Surgical and Google are Motley Fool Rule Breakers selections. The newsletter is always on the hunt for hot drug stocks and other cutting-edge picks. Click here to see all of our latest discoveries with a free 30-day trial subscription.

Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Apple is a choice of Stock Advisor. The Fool has a disclosure policy.