Cancer Mythbusters: Prostate Cancer Myths

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MEGAN: Hi. I'm Megan Riesz, and this is Cancer Mythbusters, a podcast from Dana-Farber Cancer Institute about the many myths and misconceptions in the world of cancer. Every episode, we'll take a look at a myth and debunk it with the help of our world-leading clinicians and researchers.

Prostate cancer is a disease in which cancer forms in the prostate, a gland located just below the bladder and in front of the rectum in males. In the United States, a man has a one in five chance of being diagnosed with this disease in his lifetime, but there are still a lot of myths and misconceptions surrounding prostate cancer, including how it's detected and how it's managed and treated.

Today, with Dr. Mark Pomerantz, a medical oncologist at Dana-Farber Cancer Institute, we'll go over some of those common myths and talk about the latest treatment options for prostate cancer.

Thanks so much for joining us.

DR. POMERANTZ: Thank you for having me.

MEGAN: So, I guess we'll just get stated with a very prevalent myth, which is that prostate cancer is a disease that only arises in older folks. So, what's the deal here?

DR. POMERANTZ: Well, it's a little bit complicated because there is a lot of prostate cancer out in the world and we know this from old autopsy series. In the old days, most patients who died in the hospital would have an autopsy and we learned a lot about diseases that are just out there in the community, and in the United States we know that if a man lives long enough, he is likely to develop a prostate cancer.

Well over half of all men who die of natural causes after age 70 are harboring a prostate cancer. Usually, one that they didn't know about, and what has been a little shocking where the numbers are much smaller is that when prostates are examined in people who die of younger ages tragically in accidents, say, a decent percentage of them in their thirties and forties are harboring a prostate cancer, but as you know, you walk down the street you don't see men dropping dead left and right of prostate cancer, and it's because most men die with prostate cancer, not of prostate cancer, and one of the goals and one of the things that we'll likely talk about of our research is to figure out who's who.

Who are the men who are harboring a prostate cancer that is never likely to cause harm that does not even need to be detected, and who are in the sizeable minority of men who have a prostate cancer that needs to be diagnosed and need to be cured? It is true that age is the number one risk factor for developing a prostate cancer that risk of prostate cancer does increase as men age, but we also know that there are detectable important prostate cancers to find in men as early as their forties.

MEGAN: Great. Thanks. That's really helpful. So, going off that, millions of men each year take a test to determine the level of prostate-specific antigen in their blood, the PSA test. Levels may be elevated in men with prostate cancer, but there's a common misconception that a high PSA level means that you definitely have cancer. So, can you kind of elaborate on that?

DR. POMERANTZ: Yes, and this, again, this is complicated and very controversial. All prostate cells whether they're normal prostate cells or prostate cancer cells make something called PSA, a protein that gets admitted into the bloodstream that we can detect and, generally speaking, a PSA level reflects the volume of prostate tissue, prostate stuff in the body, and we are not very good at detecting the difference between PSA made by normal prostate tissue and PSA made by prostate cancer cells.

That said, we know as the PSA rises and gets higher and higher, the odds that the PSA is coming from a cancer rather than a normal prostate increases, so the higher the PSA, the higher the likelihood that there is a cancer, and for a generation plus since the late-'80s or the early-'90s men in the United States have routinely been getting their PSAs tested, and if the PSA is elevated they are often referred for a biopsy and the urologist searches for a prostate cancer.

The reason that this is so controversial goes back to my point a minute ago about the high prevalence of prostate cancer around the world, but certainly in the United States. We know that if we go looking for prostate cancer, if we go screening for prostate cancer and go looking for it, we're going to find it, because it's out there. We know that and we know that in a large percentage of cases we didn't need to find it.

So, in Western Europe, in Canada, the doctors, epidemiologists and urologists in particular have recommended against PSA screening generally, because they know that if we go looking for it, we're going to unnecessarily find it in a large number of cases and they're not convinced that they're even finding enough of those important, more aggressive cancers that need to be cured.

In the United States, generally speaking, over the past 30 years or so, we've struck a different bargain. We've decided that we may be finding enough important cancers and saving enough lives that it is worth the known risk of over-diagnosing and over-treating many, many more men, and it is a controversy that is not yet resolved.

There have been several trials that were launched to try and determine which approach is the right one and those studies unfortunately haven't been able to definitively answer the question. There were a couple of flaws in some of the studies that have made the interpretation difficult. So, as a result, we're left with using the data that are out there to make our best guess as to how to advise patients and the leading regulatory bodies that make recommendations regarding screening — and they do it for prostate cancer, breast cancer, colon cancer and all the major cancers — are recommending that patients have a discussion with their doctor about the pros and cons of screening, the risk of over-diagnosis and the risks of not detecting an important prostate cancer early enough.

MEGAN: So, kind of going off that talking about treatment a little bit more, so one method of treatment can be active surveillance, but there is a myth that this is not a good way to treat prostate cancer that it is essentially like not receiving any treatment at all. Can you talk about that as well?

DR. POMERANTZ: Yes, and that is a myth. Active surveillance is an absolutely appropriate approach for a large percentage of patients, and I think that active surveillance and its success over the past 10-15 years informs the prostate cancer screening controversy. What active surveillance is, is an approach that we can take for the men for whom we're concerned were over-diagnosed, were diagnosed perhaps inappropriately, for men with what we call “low-grade”, and to throw some jargon out there for those in the know, Gleason 6 prostate cancer that is low-volume, very few biopsy cores.

We know that if we cure that prostate cancer, it's highly, highly curable with surgery or radiation. We know that we may be exposing men unnecessarily to side effects that that prostate cancer may never catch up with them over the course of their lifetime. Yet the cure would be associated with potentially lifelong side effects.

We now have good, solid evidence that by watching these patients carefully, looking out for a more aggressive prostate cancer that we have missed with regular PSA tests, several a year, three or four a year, and regular biopsies — at our place, we do a biopsy one year after the initial biopsy to make sure we didn't miss anything and then serial biopsies over the rest of their life – and if we detect more aggressive prostate cancer or have a hint of more aggressive prostate cancer, then we send that patient for cure, and in one of the best annotated active surveillance series out there, about 40 percent of patients on active surveillance do require curative treatment at some point over the course of the first 10 years of active surveillance, but at the very least those patients who still much more often than not get cured when they eventually do get treatment, they were able to forestall the potential side effects of treatment for a long time and which we think is a good thing.

And the reason that I say that this informs the PSA screening controversy is because one of the arguments against PSA screening is that over-diagnosis leads to overtreatment, but what active surveillance affords us is to avoid that trap. Over-diagnosis, in 2018, does not necessarily mean overtreatment, so we do help with that big, big problem with the PSA.

MEGAN: Great. Thanks so much. Another myth — surgery for prostate cancer can be an effective way of treating the cancer that can ruin patients' sex lives. Can you talk about that as well?

DR. POMERANTZ: Yes, and there is absolute truth in that it can. There are important nerves that run right alongside the prostate and the prostate is located, unfortunately, in a very busy neighborhood. The bladder is adjacent to it and the tube that leads from the bladder to outside the body called the urethra runs right through the middle of the prostate.

Even if a patient is very easily curable, it is technically very challenging to leave everything else intact behind, and it does take a skilled surgeon, skilled and experienced surgeon to leave everything else intact behind, and if those important nerves can be spared, patients can absolutely maintain sexual function. If the cancer is more aggressive and the surgeon needs to take a wider surgical margin, those nerves are at risk and sexual function can be affected.

When we take a step back and look at patient-reported outcomes over the past several years, there have been a couple of decent studies over the past 10 years that asked patients very directly what's life like before, what's life like after surgery. Generally speaking, sexual function is a little worse after surgery than it was before, but most men are not rendered impotent.

That said, even when the nerves need to be taken, even when sexual function is obliterated, the urologist does have tricks for enabling people to maintain an erection, have sex. It does sometimes require intervention or medicines, but the urologist can address that problem post-surgery.

MEGAN: So, another false train of thought is often that you can't have prostate cancer if you don't have any symptoms. So, can you talk about this and explain some common symptoms?

DR. POMERANTZ: So, in the PSA era, in a population that is generally PSA-screened as most men in the United States were — up through 2011-2012 screening rates have actually declined a little bit, which is another topic — for a PSA-screened population most men are diagnosed without symptoms and elevated PSA in and of itself doesn't cause symptoms and PSA may be elevated even though a tumor is confined to the prostate and not pressing on anything that would cause symptoms, and when the patient is sent for biopsy, the cancer is discovered and the patient had no symptoms at all.

In the pre-PSA era or in a patient that is not PSA-screened and comes to medical attention because of symptoms, one of the most common symptoms is urinary problems whether it's urinary retention because the tumor is squeezing on that tube that comes from the bladder called the urethra or the bladder itself making urination difficult. There may be a little blood in the urine if those tissues get irritated. In the pre-PSA era, we would see this more often, but in the post-PSA era we see in about 10 percent of cases a patient presents with pain related to the spread of the prostate cancer. The most common place for prostate cancer to spread is to the bone and, if the tumor in the bone gets big enough, it can cause pain and sometimes that's what brings a patient to medical attention, but in a PSA-screened population, again, most patients don't have symptoms.

MEGAN: So, to kind of wrap it up, any parting words for newly diagnosed patients or anyone else who might be listening, what they should know about the disease or any myths and misconceptions we haven't addressed that you've run into a lot?

DR. POMERANTZ: One message that I think is important for patients that are diagnosed with prostate cancer is that it is a highly treatable disease even in the advanced setting, even for the patients who present with widespread disease.

Disease that can no longer be cured, the disease needs to be corralled in one small area for us to cure it by surgery or radiation, but even if it cannot be cured, prostate cancer has an Achilles' heel that we can take advantage of — prostate cancer is addicted to the hormone testosterone, and by manipulating that hormone, we can reliably induce remissions and we're getting better and better at it. It is a disease that can become a chronic one that we can manage for a long, long time.

MEGAN: Great. Thanks so much for clearing all of this up and for being here today.

DR. POMERANTZ: My pleasure. Thank you for having me.

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