When to Do a Prostate Biopsy, and When Not To

A prostate biopsy is justified when suspicion of clinically significant cancer is high: an abnormal rectal examination, a PSA (prostate-specific antigen) confirmed above the age-adjusted level on at least two readings, or a rising PSA in a man with a strong family history. Urinary infection must be excluded first. In men who are very old, very sick or unwilling to undergo major treatment, a biopsy is often better avoided.

A prostate biopsy takes small samples of prostate tissue with a fine needle, usually under ultrasound guidance, so that a pathologist can confirm or exclude cancer and judge how aggressive it is. It is the step that turns suspicion into diagnosis, and it is the step at which over-investigation carries real risk. Dr. Nitin Shrivastava, a urologist and uro-oncologist, frames the biopsy decision as a balance between two failures: missing an aggressive cancer, and putting men through a risky procedure, and possibly treatment, that they never needed. This article sets out how he strikes that balance, how he approaches the choice of biopsy route, and where MRI and CT fit. The overall diagnostic pathway is described in the complete guide to prostate cancer early detection.

Why not every raised PSA leads to a biopsy

Prostate biopsy is not a routine test, and Dr. Shrivastava is clear that it cannot be done on everyone. It carries a risk of bleeding and of infection. The task is to select the right patient and to biopsy him at the right time.

The reason for caution lies in the nature of the disease. Prostate cancer spans a wide spectrum, from indolent tumours that will never affect a man's survival to aggressive cancers that can kill within months. The objective, in his words, is to find clinically significant cancer. Missing an indolent cancer is acceptable; missing an aggressive one is not. Because PSA and the rectal examination can both be abnormal for many reasons, a low threshold for biopsy leads directly to over-investigation and over-treatment.

When to do a prostate biopsy: which patients need one

Dr. Shrivastava proceeds to biopsy in two broad groups of patients:

• The symptomatic patient with abnormal findings: a man with urinary symptoms whose rectal examination was abnormal and whose PSA was high.
• The asymptomatic high-risk patient with a raised PSA: a man who is otherwise entirely normal but has a strong family history, whose PSA has come back high.

Within these groups, the triggers he applies are specific:

1. PSA above the age-adjusted level on at least two occasions. A single high reading is never enough. The thresholds are set out in the guide to age-adjusted PSA levels, density and velocity.
2. A PSA that keeps rising, particularly on two occasions in a man with a family history.
3. A suspicious borderline result. Where the PSA is borderline, a PSA density above 0.15 or a PSA velocity above 0.75 ng/mL per year makes the case for biopsy.
4. High clinical suspicion. If the overall picture points strongly to prostate cancer, he advises going ahead with the biopsy.

The one check before every biopsy: exclude urinary infection

The single thing Dr. Shrivastava asks every clinician to be certain of before a biopsy is that the patient does not have a urinary infection causing the high PSA. He repeated the point in his closing summary: always rule out urinary infection before planning any investigation.

A man with fever, burning on passing urine and infection on urine examination should have the infection treated first, with the PSA repeated a few weeks after antibiotics, as described in the PSA article. Biopsying while an infection is active adds risk, and the raised PSA that prompted the biopsy may simply reflect the infection.

Prostate biopsy risks and how to discuss them

The biopsy conversation should begin before the first PSA is ordered. Dr. Shrivastava explains three things to the patient:

• The benefit: an aggressive cancer will not be missed.
• The risk of the biopsy itself: he puts the risk of complications at less than 1%.
• The consequence of a positive result: if the biopsy shows cancer, further treatment is likely to follow.

Minor effects such as blood in the urine, semen or stool are common for a short time after a prostate biopsy and usually settle on their own; serious infection is the complication that preparation aims to prevent.

Transrectal or transperineal prostate biopsy?

Both routes are acceptable, and Dr. Shrivastava's message to clinicians who use the transrectal approach is that they need not change. The two approaches differ in where the needle passes:

• Transrectal biopsy passes the needle through the wall of the rectum into the prostate. In Dr. Shrivastava's experience, it is the approach used in most African countries and in much of India.
• Transperineal biopsy passes the needle through the skin of the perineum, the area between the scrotum and the anus. It is newer and increasingly popular.

According to Dr. Shrivastava, the latest research shows no difference between the two in efficacy, so a clinician performing transrectal biopsy is doing an appropriate procedure. Current European Association of Urology guidance prefers the transperineal route where it is available, chiefly because it carries a lower risk of infection.

Povidone-iodine rectal preparation

For transrectal biopsy, one step carries a strong recommendation: cleansing the rectum with povidone-iodine before the procedure. Dr. Shrivastava highlighted this recommendation for every transrectal biopsy. Povidone-iodine cleansing reduces the risk of infection that comes with passing a needle through the rectal wall.

He also noted that many patients who travel to him from the African continent arrive with a good biopsy report already in hand, a reflection of sound practice by the referring doctors.

The role of MRI in prostate cancer diagnosis

MRI is the imaging test used to look for cancer within the prostate. Dr. Shrivastava's guidance is flexible: if MRI is available at the centre, it is fine to do it before the biopsy, and it can also be done afterwards. Current European guidance recommends MRI before biopsy where it is available, because it can identify suspicious areas for targeted sampling and can spare some men a biopsy.

MRI also has a specific use in catheterised men, in whom PSA is raised by the catheter itself. If the PSA keeps rising in such a patient, he advises an MRI to establish what is happening inside the gland.

Can a CT scan diagnose prostate cancer?

No. A CT scan cannot confirm prostate cancer and is not used to look for it; MRI is. The question came from a doctor working where CT is more accessible than MRI, and Dr. Shrivastava's answer was practical rather than discouraging.

CT has a clear role once cancer is known to be present. If MRI is not available, CT is very useful for staging: it shows whether the cancer has spread outside the prostate. His pathway for a centre without MRI is therefore straightforward:

1. Do the PSA.
2. Do the biopsy.
3. Do the CT scan.

At the end of that sequence the clinician knows whether there is a cancer and how far it has spread. In his words, if there is no MRI, there is no need to worry. How staging and grading then shape treatment is covered in the guide to prostate cancer staging and the Gleason score by Dr. Amit Goel.

When not to do a prostate biopsy

The final point in Dr. Shrivastava's summary concerns the men who should not be pushed through the pathway at all. In patients who are very old, very sick, or who do not want any further major treatment, he will probably not plan a biopsy. Instead, he discusses with the patient the risks and benefits of not investigating further and, as he put it, leaves him in peace.

This is the logical end of the clinically significant cancer principle. A biopsy is worth its risks only if its result could change what happens next. For a man who would not be a candidate for treatment, or who would decline it, a positive biopsy adds risk and anxiety without adding benefit.

How the biopsy decision fits the wider pathway

Dr. Shrivastava's sequence can be read as a series of filters, each designed to reduce the number of unnecessary biopsies without letting an aggressive cancer through:

The questions doctors put to Dr. Shrivastava on catheterised patients, CT and PSA cut-offs are recorded in the Live Discussion from this masterclass. For the management of benign enlargement, repeat TURP and recovery after prostate surgery, see the article on BPH and life after prostate surgery. Further urology content is on the urology hub.