In short: no. Benign prostatic hyperplasia, the growth of the prostate that comes with age, is not a premalignant lesion: there's no evidence that it's an early stage of cancer or that it turns into cancer. They're different diseases, which generally arise in different areas of the gland. You can have one without the other, or both at the same time. Having a large prostate doesn't protect you from cancer, and there's no proof that it makes you more vulnerable to it either. That's why it's worth understanding the difference clearly.
It's one of the most common fears. You're told "your prostate is enlarged," and what many men hear is "cancer." Let's take it one step at a time.
What does it mean that prostatic hyperplasia is benign?
The full name is benign prostatic hyperplasia, and "benign" means exactly that: it's not cancer.
- In hyperplasia, the prostate has more cells than normal, but those cells behave in an orderly way. They don't invade other tissues or spread to other organs.
- In cancer, cells grow out of control, invade tissues where they don't belong, and can spread.
One way to picture it: think of the prostate as a city. In hyperplasia, the city grows: there are more houses and more buildings, but everything follows the rules and no one encroaches on the neighbors. In cancer, there's no order: construction grows out of control and spills onto other people's land.
Hyperplasia and prostate cancer usually arise in different areas
The prostate isn't uniform: it has zones that behave differently.
- Hyperplasia arises in the transition zone [1].
- Most cancers arise somewhere else. In a classic 1988 study that analyzed surgically removed prostates, of the 88 cancers whose origin could be identified, 68% had arisen in the peripheral zone, 24% in the transition zone, and 8% in the central zone [2].
Note the nuance: "generally" doesn't mean "always." A quarter of those cancers arose in the same zone as the hyperplasia, and they often seemed to originate inside its nodules [2]. Being in the same place doesn't prove that one turns into the other, but it does explain why they can occur together.
A review of the relationship between the two diseases sums it up this way: they share some features, but they have important differences in how they look under the microscope and where they're located [3].
Are hyperplasia and prostate cancer related at all?
Here it pays to be precise. Several observational studies found that men with hyperplasia are diagnosed with prostate cancer more often, although in follow-up studies, which are the most reliable, the increase was small and barely significant [4]. A very likely explanation is that these men see the doctor more often and have more tests because of their symptoms, which makes it easier to find a cancer that would otherwise have gone unnoticed [3]. Two things appearing together doesn't prove that one causes the other.
Researchers still don't know what's behind that association [3]. The possibilities are that:
- one influences the other;
- they share factors, such as dependence on hormones, inflammation, or metabolic disorders;
- or simply that men with prostate symptoms get more tests, and so more cancer is found in them.
The very authors of the review that pooled those studies call for better-designed research to confirm it [4].
Prostatic hyperplasia is not premalignant
A premalignant lesion is one that can turn into cancer over time. Hyperplasia is not one: there's no evidence that it's an early stage of cancer, or that a large prostate "evolves" into cancer over the years.
The lesion that research points to as the main precursor of prostate cancer is a different one: high-grade prostatic intraepithelial neoplasia (PIN), which, like cancer, appears mostly in the peripheral zone [5]. It's a finding that can only be seen under the microscope, in a biopsy, and it has nothing to do with the size of the prostate.
Urinary symptoms are not usually a sign of prostate cancer
Another common misconception is thinking that if you have trouble urinating, "something bad" is going on.
The European guidelines state explicitly that part of caring for a man with urinary symptoms is reassuring him: there is no definite link between those symptoms and prostate cancer [6]. A weak stream, getting up at night, or urgency are usually due to hyperplasia, the bladder, or other causes [6].
But this has an important flip side: early-stage prostate cancer usually causes no symptoms. Symptoms show up late: when the cancer advances locally, it can cause trouble urinating, urinary retention, or blood in the urine [7]. That's why "I have no symptoms" doesn't rule out cancer either.
| Benign prostatic hyperplasia | Prostate cancer | |
|---|---|---|
| Is it cancer? | No | Yes |
| How it grows | In an orderly way, without invading | Out of control; can invade and spread |
| Where it most often arises | Transition zone [1] | Peripheral zone [2] |
| Urinary symptoms | Common when it squeezes the urethra | Uncommon in early stages [7] |
| Is it premalignant? | No: there's no evidence it turns into cancer | Its main precursor is high-grade PIN [5] |
| Can they coexist? | Yes | Yes |
PSA can rise because of hyperplasia or cancer
Prostate-specific antigen (PSA) is a blood test that helps raise suspicion of prostate cancer. But it's specific to the prostate, not to cancer: it can also go up because of hyperplasia, inflammation (prostatitis), and other causes that aren't cancer [7].
That's why a high PSA doesn't always mean cancer, although the higher it is, the more likely cancer becomes [7]. It's interpreted together with other information. I explain it in detail in PSA test: when to get it and how to read it.
What does this mean if you have an enlarged prostate?
- Having a large prostate doesn't mean having cancer. Hyperplasia is not premalignant: there's no evidence that your prostate "will turn into" cancer.
- But you're not protected either. Prostate cancer is the second most commonly diagnosed cancer in men worldwide [7], and age is one of its main risk factors [7].
- Urinary symptoms are not usually the warning sign of cancer. Early cancer usually doesn't cause them; when it advances, it can cause trouble urinating or blood in the urine [7].
- Early detection is an individual decision, which can be considered whether or not you have urinary symptoms [7]. The European guidelines state that it can be recommended from age 50; from 45 if you have a family history of prostate cancer or are of African descent, and from 40 in carriers of mutations in the BRCA2 gene [7]. They also recommend discussing its downside: it can detect cancers that would never have caused problems and lead to unnecessary treatment [7]. Talk it over with your doctor.
If at some point you're offered a biopsy, you may find it useful to read Does a prostate biopsy cause impotence?.
And if you want to understand why the prostate grows in the first place, I explain it in Why does the prostate grow with age?.
Frequently asked questions
Does prostatic hyperplasia increase the risk of cancer? Some observational studies find slightly more cancer in men with hyperplasia, but it's not known whether that's a cause-and-effect relationship or whether it's due to shared factors or to these men getting more tests. What we do know is that hyperplasia is not premalignant: there's no evidence that it turns into cancer.
If my PSA came back high, do I have cancer? Not necessarily. PSA also goes up because of hyperplasia, prostatitis, and other causes that aren't cancer, although the higher it is, the more likely cancer becomes. Your doctor interprets it together with your age, the physical exam, and, if needed, other tests.
Can I have hyperplasia and cancer at the same time? Yes. They're different diseases, but both are common with age and can coexist.