Digital rectal examination

How is prostate cancer diagnosed?

General medical examination
During a visit to the doctor, a male patient over the age of 50 may be asked questions about his general medical health and whether he has any specific symptoms. The answers that are given may prompt the doctor to carry out further tests to see if there is a possibility that the patient may have prostate cancer. 

Physical examination
A general physical examination can tell the doctor many things about the general medical health of a patient. A rectal examination is a more specific examination to help diagnose or rule out prostate cancer. The doctor will insert a lubricated, gloved finger into the back passage (rectum) to assess the size and shape of the prostate gland.

How is prostate cancer diagnosed?

PSA blood test
Prostate specific antigen (PSA) is a protein produced by both normal and cancer cells in the prostate gland. As the prostate gland gets larger with age, there is an increase in the normal (expected) levels of PSA in the blood. A rise in PSA levels can indicate that there may be cancer cells growing in the prostate gland, as weight for weight, cancer cells produce more PSA in the blood than benign (non-cancerous) cells. However, there can be other causes for an elevated PSA, the most common one is a urinary infection.

A higher than expected level of PSA is only a warning sign for prostate cancer and further investigations are needed to be sure if cancer is present or to rule it out.

How is prostate cancer diagnosed?

PSA blood test
PSA in blood is measured as the weight of PSA protein in a millilitre (mL) of blood. The weight of PSA protein is measured in nanograms (ng). The expected normal range for PSA is generally between 0 and 4 nanograms per millilitre (ng/mL).

However, as the prostate gets larger with age, the normal PSA range changes slightly. PSA levels that reflect this change (called age-related PSA-levels) give a more accurate clinical picture. In general, the higher the PSA level the greater the chance of a patient having prostate cancer. Patients with widespread cancer may have levels of more than 100 ng/mL.

Ultrasound scan

How is prostate cancer diagnosed?

Ultrasound examination and biopsy
The prostate can be visualised using an ultrasound scanner. A well-lubricated ultrasound probe, similar in size to a finger, is inserted into the rectum and images of the prostate gland are displayed on a screen. This technique also provides pictures of the seminal vesicles and other structures surrounding the gland.

The images that are produced may help to identify areas within the gland that may be malignant (cancerous), but the only way to prove that there is a cancer present is to take a biopsy (a small piece of prostate gland material obtained by a special needle).

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How is prostate cancer diagnosed?

Ultrasound examination and biopsy
If the doctor intends to take a biopsy during the ultrasound scan the patient will be told before the probe is inserted. The special biopsy needle is a small needle that is inserted with the ultrasound probe so that it can be moved to the area that the ultrasound scan has shown may have cancer cells present.

Normally a local anaesthetic is injected around the prostate to minimise any discomfort. Antibiotics will also be used to help prevent any infection occurring. After the procedure, the patient may notice some blood in the urine, semen and stools. This is quite common and usually settles down within a week or two.

Typically, biopsies are normally taken from 10–12 different areas within the prostate. The pathologist will examine this tissue in the laboratory and the results will confirm or rule out a diagnosis of prostate cancer.

How is prostate cancer diagnosed?

Bone scan
A bone scan may be used to check whether prostate cancer has spread and invaded the bones, but it is not always necessary. A bone scan is only performed once a diagnosis of prostate cancer has been confirmed by other tests. It is usually requested if the PSA level in the blood is high, indicating that the cancer may have become widespread.

A bone scan is usually painless. A tiny, harmless quantity of a radioactive material is injected into a vein. The radioactive material is carried in the blood to any cancer cells within the bony skeleton where it sticks to them. After a few hours the bones are scanned using a special camera, similar to an X-ray machine. Any cancer cells present will be detected because of the radioactive material attached to them.

How is prostate cancer diagnosed?

Computer tomography (CT) or magnetic resonance imaging (MRI) scans
A computer tomography (CT) scan or magnetic resonance imagining (MRI) scan can sometimes be used to obtain detailed pictures of the prostate and the surrounding tissue, although it may not be necessary in all cases.

Both types of scan are quite painless. The CT scan uses X-rays and the MRI uses magnetic fields to produce their images.