What doctors look for when checking for prostate cancer

Prostate cancer screening uses two main tests: a blood test that measures PSA (prostate-specific antigen), and a digital rectal exam where a doctor inserts a gloved finger into the rectum to feel the prostate gland. Neither test diagnoses cancer on its own. Both can show something might be wrong, but only a biopsy—taking a small tissue sample—can confirm whether cancer is actually present.

The PSA blood test is simpler and less uncomfortable. It measures a protein the prostate makes, and higher levels can signal cancer, but they can also mean infection, enlargement, or nothing at all. The digital rectal exam lets a doctor feel the prostate's size and texture directly, which can catch some cancers the PSA test misses. Many doctors offer both tests together during screening.

Key Takeaways

  • PSA blood tests and digital rectal exams are the two main screening methods, but neither one diagnoses cancer by itself.
  • A biopsy—removing a small tissue sample—is the only way to confirm prostate cancer, and doctors only order one if screening results suggest cancer might be present.
  • Screening decisions depend on your age, family history, and personal preference, because prostate cancer often grows slowly and may never cause harm.
  • If a screening test shows something abnormal, your doctor will discuss next steps, which might include repeat testing, imaging, or a biopsy.

The PSA blood test and what the numbers mean

PSA stands for prostate-specific antigen. Your prostate makes this protein naturally, and a small amount enters the bloodstream. A PSA test measures how much is there. Most labs consider a PSA level below 4 nanograms per milliliter (ng/mL) normal, though this varies slightly between labs and by age.

A higher PSA can mean cancer, but it can also mean your prostate is enlarged, infected, or inflamed—conditions that are not cancer. PSA also rises slightly with age and after activities like cycling or ejaculation. Because of this, doctors do not diagnose cancer based on PSA alone. Instead, they look at the number itself, how fast it is rising over time, and what the digital rectal exam shows.

If your PSA is elevated, your doctor might repeat the test a few weeks later to see if it was a temporary spike. They might also calculate your PSA velocity—how much it has risen year to year—because a rapid climb is more concerning than a stable high number.

The digital rectal exam and what it involves

A digital rectal exam (DRE) takes about a minute. You bend forward or lie on your side, and your doctor inserts a gloved, lubricated finger into your rectum to feel the prostate gland through the rectal wall. The doctor is checking for lumps, hard spots, or areas that feel abnormal compared to normal prostate tissue.

The exam is uncomfortable but not painful for most people. Some men find it embarrassing, which is a real reason some avoid screening altogether. Talking to your doctor beforehand about what to expect can help. The DRE can sometimes detect cancer that a PSA test misses, especially in men with normal or only slightly elevated PSA levels.

When a biopsy becomes necessary

A biopsy is the only test that can actually diagnose prostate cancer. Your doctor orders one if the PSA is elevated, the DRE feels abnormal, or both. A biopsy uses a thin needle to remove 10 to 12 tiny samples of prostate tissue, usually guided by ultrasound so the doctor can see where to aim.

The procedure takes 10 to 15 minutes and is done in a doctor's office or outpatient clinic. You receive local anesthesia to numb the area. Afterward, you may have mild discomfort, blood in the urine or stool, or blood in the semen for a few days—all normal. A pathologist then examines the tissue samples under a microscope to look for cancer cells.

If cancer is found, the pathologist assigns it a Gleason score, which describes how aggressive the cancer looks. This score, along with the PSA level and how much of the biopsy samples contained cancer, helps your doctor understand how serious it is and what treatment options make sense.

Imaging tests if cancer is suspected

If a biopsy shows cancer, your doctor may order imaging tests to see whether it has spread beyond the prostate. An MRI (magnetic resonance imaging) can show the size and location of the cancer within the prostate and whether it has reached nearby tissues. A bone scan or CT scan might be used if the cancer appears aggressive or the PSA is very high, because prostate cancer sometimes spreads to bones or lymph nodes.

These tests help your doctor stage the cancer—determine how far it has spread—which is essential for deciding on treatment. Not every man with prostate cancer needs every imaging test; your doctor will recommend based on the biopsy results and other risk factors.

Screening decisions and who should be tested

Prostate cancer screening is not recommended for all men. The American Cancer Society suggests that men have a chance to make an informed decision about screening starting at age 50, or at age 40 to 45 if they are Black or have a family history of prostate cancer. Men at very high risk—those with multiple relatives who had prostate cancer—may want to discuss screening even earlier.

The decision to screen depends on your age, health, family history, and how you feel about the risks and benefits. Prostate cancer often grows slowly and may never cause symptoms or shorten your life. Screening can find cancers that would never have harmed you, leading to treatment you did not need. On the other hand, early detection of aggressive cancer can save lives. Your doctor can help you weigh these factors and decide what is right for you.

If you decide not to screen now, you can revisit the decision later. Screening is not a one-time event; men who choose it typically have PSA tests every one to two years, depending on their results and risk level.

What happens after an abnormal screening result

An abnormal PSA or DRE does not mean you have cancer. Your doctor's next step depends on how abnormal the result is and your other risk factors. Common next steps include repeating the PSA test in a few weeks, ordering an MRI of the prostate, or discussing a biopsy.

Some doctors now use an MRI before biopsy to get a better picture of the prostate and identify which areas, if any, look suspicious. This can help avoid unnecessary biopsies in men whose imaging looks normal. If an MRI shows something concerning, a targeted biopsy samples only the suspicious area rather than the whole gland.

Throughout this process, your doctor should explain what each test shows and what the results mean for you. Do not hesitate to ask questions or ask for a second opinion if you are unsure about the next step.

Frequently Asked Questions

Does a high PSA always mean I have prostate cancer?

No. A high PSA can result from infection, enlargement, inflammation, or age. Only a biopsy can confirm cancer. Your doctor will consider your PSA level, how fast it is rising, your age, family history, and the digital rectal exam before recommending a biopsy.

Is the digital rectal exam painful?

It is uncomfortable but not painful for most men. It lasts about a minute. If you are anxious about it, tell your doctor beforehand—they can explain what to expect and may offer ways to make you more comfortable.

What does a Gleason score mean?

A Gleason score describes how aggressive prostate cancer looks under the microscope. Scores range from 6 to 10. Lower scores mean the cancer looks more like normal prostate tissue and tends to grow slowly. Higher scores mean it looks more abnormal and may grow faster.

Can I get prostate cancer screening without a digital rectal exam?

Yes. Some men choose PSA testing alone, and some doctors now offer MRI instead of or before a biopsy. Talk to your doctor about which tests you are comfortable with and which ones they recommend based on your risk factors.

How often should I be screened if my PSA is normal?

If you choose screening and your PSA is normal, most doctors recommend retesting every one to two years, depending on your age and risk level. Your doctor will recommend a schedule based on your individual situation.