Screening with the prostate-specific antigen (PSA) test can detect early-stage prostate cancer while it’s still asymptomatic. But some men are diagnosed with prostate cancer only after symptoms appear. For insights into how doctors distinguish prostate cancer from other noncancerous problems affecting the prostate, we spoke with Dr. Marc B. Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, and editor in chief of the “Harvard Medical School Guide to Prostate Diseases.”

Q: What are the first symptoms a man might notice if he has early-stage prostate cancer?

A: I first want to mention that most men who are diagnosed with prostate cancer — including many with advanced forms of the disease — do not present with symptoms. When symptoms do appear in a man with early-stage disease, they affect his ability to urinate. Lower urinary tract symptoms (LUTS), as we call them, include urinary frequency, urgency, difficulty starting or stopping a stream, getting up repeatedly at night to pee, or feeling like you’re never able to fully empty your bladder. LUTS can develop if a tumor grows large enough to physically obstruct the urethra, which is the tube that carries urine out of the body. The diseased prostate can also push up against the bladder, thereby lessening its capacity to hold fluid.

But more often than not, urinary symptoms result from other problems with the prostate. Benign prostatic hyperplasia (BPH), for instance, is a natural enlargement of the prostate that affects most men as they get older. Some men develop LUTS if the prostate and surrounding tissues become inflamed; this is called prostatitis. And if a man experiences burning sensations while urinating, then he likely has a problem with his bladder, not his prostate. Men who experience any of these urinary symptoms should be evaluated by a doctor.

Q: How would a doctor begin to narrow down the diagnosis?

A: Assuming prostatitis and bladder disease have been ruled out, the next step is to differentiate between prostate cancer and BPH. Men with BPH typically have two kinds of urinary symptoms.

Voiding symptoms caused by obstruction at the bladder outlet: they include a weak or intermittent stream and incomplete emptying

Storage symptoms caused by an overactive and sensitive bladder: these symptoms include a sudden urge to urinate, or needing to urinate more often during the day and night.

A red flag for prostate cancer would be having storage symptoms only, or urinary symptoms that develop very rapidly. That would be unusual for LUTS caused by BPH. These symptoms can be assessed by having men fill out a questionnaire called American Urological Association Symptom Score.

The doctor can also do a digital rectal examination (DRE). If the prostate feels symmetrically enlarged — meaning the gland is bigger but in a uniform and evenly distributed way — then that helps to establish a BPH diagnosis. If there’s asymmetry in the gland, or if the doctor feels a hard nodule, then the patient needs to be referred to a urologist for further evaluation. DREs are performed less often now than they used to be, and many doctors have no training in the procedure. That’s unfortunate, since in my view a DRE is one of the most important components of a physical examination.

Another thing people need to recognize is that BPH can eventually lead to kidney failure, or to a medical emergency called acute urinary retention, which is a sudden inability to urinate at all. So, BPH should really be treated to avoid these serious complications.

Q: Can PSA help doctors differentiate between BPH and prostate cancer?

A: It can. PSA levels rise in men with BPH as they also do in men prostate cancer, simply because a larger, more irritated prostate gland releases more PSA into blood than a normal prostate does. Usually, we start patients on BPH drugs that can make it easier to urinate while also lowering PSA. Then after six weeks or so, we test the PSA again. If the levels come back high, then the next step is typically a magnetic resonance imaging (MRI) scan of the prostate. If the MRI is normal and the PSA is proportionate to the size of the prostate, then that helps to rule out cancer. In such cases, we can consider avoiding a prostate biopsy — at least temporarily — and continue to monitor PSA instead.

Q: What are the symptoms of more advanced prostate cancer that’s begun to metastasize or spread?

A: Even with advanced prostate cancer, many patients are still completely asymptomatic. Fortunately, we’ve gotten much better at treating advanced disease, especially now that we have better scans to identify small deposits of cancer and methods to eliminate them. When symptoms do appear, especially if the cancer has spread to the bones, men typically show up with back or shoulder pain — basically pain where metastases grow near bone surfaces where nerves are located. Men who present with persistent back pain that’s getting worse despite treatment interventions should be considered for further evaluations such as X-ray or MRI.

Q: What about fatigue and weight loss?

A: These sorts of symptoms are more common in other cancers such as colon cancer, lung cancer, and lymphoma. You typically don’t see them in prostate cancer unless the cancer is very advanced with widespread metastases.

Q: Thanks for walking us through this complex topic.

A: You’re welcome! The challenge for patients and physicians alike is to identify the causes of overlapping urinary symptoms, which are so common among men with either prostate cancer or BPH. Hopefully this discussion was helpful.

(C.W. Schmidt is editor of the Harvard Medical School Annual Report on Prostate Diseases)

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