JOHN YANG: This year alone, nearly 300,000 American men are expected to be diagnosed with prostate cancer, though most of those diagnosed with it don't die from it.

On this final day of prostate cancer awareness month, Ali Rogin takes a look at screening diagnosis and treatment of the disease and what it means to live with it.

ALI ROGIN: Prostate cancer is the most common cancer among men in the U.S. and the second most common cause of cancer related deaths and glaring racial disparities exist within the disease.

One in eight men will be diagnosed with prostate cancer during their lifetime, but that rate increases to one and six for African American men.

But a diagnosis doesn't have to be life changing.

In fact, many men with certain types of slow growing prostate cancer are able to forego surgery and treatment altogether.

Dr. Charles Ryan is a Genital Urinary Oncologist, and he heads the Prostate Cancer Foundation.

Dr. Ryan, thank you so much for joining us.

Let's start with the absolute basics, what is prostate cancer?

And where does it originate in the body?

DR. CHARLES RYAN, CEO, Prostate Cancer Foundation: Sure, well thank you for having me, and -- and to explain this important issue.

The prostate is a gland that is very important in male reproduction, it essentially produces the fluid that allows the sperm to -- to fertilize an egg.

So without it, we are not able to reproduce.

It exists at the base of the bladder.

And it is really part of the male urinary tract, but also the male genital tract, allowing sperm to be released from the body.

ALI ROGIN: And I know the options for prostate cancer screening.

And whether or not someone is a good candidate for it, is a complicated issue.

There are lots of factors that go into that.

But let's start with what sort of screening is available for prostate cancer?

DR. CHARLES RYAN: Right.

So the prostate cancer screening has long involved a test, a blood test called a PSA test, and for many years involved a digital rectal exam, which is also called the finger test.

So a doctor inserting his finger into the rectum of the patient to see if there's a tumor that one can feel.

We also now incorporate MRI scanning.

And over time the MRI scan is really replacing the digital rectal exam, because it's less uncomfortable and it's actually more accurate.

ALI ROGIN: The U.S. Preventive Services Task Force, which is an independent body that makes recommendations on disease prevention, recommends currently that men aged 55 to 69 not get automatically screened, but rather discuss the pros and cons of screening with their provider.

The U.S. PTF doesn't recommend screening at all for men over the age of 70.

But my question is, if prostate cancer is, as we said, so widespread, why shouldn't all men get tested?

DR. CHARLES RYAN: Well, it's important to remember that when regard -- with regards to screening that there are three distinct groups of individuals who can -- who can get prostate cancer.

The first is a group that have such low-risk disease that they may not require any treatment.

And our current estimates are that that may constitute 20% to 25% of all of the men diagnosed with prostate cancer in the United States.

There's a second group, which is patients who are curable with -- with treatment options, as long as the disease is confined to the prostate.

So those are the ones who really benefit the most from screening and early detection.

There's a third group for whom the treatment options are not optimal.

And they are not guaranteed a cure with current -- current treatment options.

And for those we need to do -- we need to do more research and develop better treatment options.

It's important to remember also that screening does not necessarily automatically lead to a certain type of treatment.

And that's been some of the misunderstanding that's created the problems that we're seeing now, with a rising incidence of prostate cancer and its advanced stages.

ALI ROGIN: And what are the current treatment options for people that are in those cohorts for whom treatment would work?

DR. CHARLES RYAN: So for the low-risk group, we have a program called Active Surveillance, which is monitoring, and it's not that they never receive treatment, some of them and many of them actually do, but it's delayed until later.

Those involve repeat biopsies, MRI scans, and close surveillance from a treating physician.

But for men who are in the curable group, the main treatments remain surgical removal of the prostate radiation therapy to the prostate, which has really evolved a lot over recent years.

And then combinations with other approaches, such as hormonal approaches that may help radiation do a better job.

In advanced disease, we've seen a tremendous growth of a number of therapies with a whole variety of different mechanisms of action, that extend life and improve its quality for men, even with advanced stage metastatic prostate cancer.

ALI ROGIN: We mentioned in the introduction, this persistent racial disparity in terms of diagnoses and outcomes.

Why does it seem that black men continue to be disproportionately affected by prostate cancer?

DR. CHARLES RYAN: The cause of that disparity are complex and probably include a combination of both biological factors, genetic factors, as well as societal factors.

And one key observation is that prostate cancer occurring in a black man is likely to occur earlier in life and such that a screening when performed earlier, may detect a curable cancer earlier than it would be for -- for example, a non-black man.

So starting screening at the age of 50, may not be adequate, for example, for a population where the disease is likely to begin even as early as age 40.

ALI ROGIN: I want to return to the issue of active surveillance that you mentioned.

Some studies have shown that some people on active surveillance when they're not receiving treatment, they eventually do have to undergo some sort of treatment, does that indicate the testing needs to advance in terms of being able to determine the potential seriousness of slow-growing prostate cancer?

DR. CHARLES RYAN: Well, it's a wonderful question because we, in fact, are learning a lot more about the biological heterogeneity of this disease.

And so when we're making a decision about whether a patient would be an ideal candidate for active surveillance, we incorporate genetic studies now, and genetic factors that look at the interplay of a number of genes, and that can help us further stratify a potential patient for immediate treatment or deferred treatment.

ALI ROGIN: The treatments and the surgeries that currently exist for men dealing with prostate cancer tend to be very serious and potentially life altering.

What are the prospects that you see for the future of that discipline, isn't getting better, isn't allowing men to continue to have happy and healthy lives?

DR. CHARLES RYAN: Because of the location of the prostate at the base of the bladder and as a -- as a key component to the male sexual function, the worries around treatment side effects do include urinary function, and sexual function.

Over the course of the past couple of decades, the surgical field has made tremendous strides in preserving sexual function, and improving and preserving good urinary function.

So one of the problems we have when we're thinking about the treatment related side effects is where are we getting our data from?

If we're talking to patients who had their treatment 15, 20 years ago, it was a very different studying back then than what we see now.

Of course, there are cases where the -- the cancer is more advanced, and it's more difficult to preserve those functions.

But -- but today, many men are quite optimistic about their treatment.

And there are many men out there living happy normal lives after undergoing curative treatment for prostate cancer.

ALI ROGIN: Dr. Charles Ryan, Head of the Prostate Cancer Foundation, thank you so much for joining us.

DR. CHARLES RYAN: My pleasure.