Prostate cancer

Condition

Prostate cancer is the most common adult cancer in New Zealand men after skin cancer, and while the risk of dying from prostate cancer is quite low, it can recur after curative treatment, and for this reason men are usually kept on long term surveillance, either via their urologist or GP.

The diagnosis of prostate cancer is first considered when a man has a blood test showing an elevated level of PSA (prostate specific antigen), but this protein is actually an enzyme secreted in the prostate fluid and it has an important role in assisting sperm function. The PSA blood test is a very poor quality detection (or "screening") test for prostate cancer as PSA levels can be raised for many other reasons, including benign enlargement (non-cancerous growth) of the prostate, infection or inflammation, recent intercourse, use of certain drugs like Voltaren and Brufen, and even excessive hours on a bicycle saddle.

Of all men with a raised PSA result, only about 30-50% will end up having a diagnosis of prostate cancer.

The Urological Society of Australia and New Zealand (USANZ) recommends that men have a first PSA test at the age of 40, or between the ages of 40 and 50, to determine their lifelong risk of prostate cancer. If the level is above 1.0 at age 40, a man has a higher risk of developing prostate cancer in the course of his life. The acceptable cutoff level for PSA rises with age, owing mainly to growth of the prostate, so that after age 65 a level up to 6.5 is acceptable and in the "normal range". However prostate cancer can exist at any PSA level. For this reason a rectal exam by your GP and assessment by a urologist is important in the process of ruling out prostate cancer.

Prostate cancer is traditionally diagnosed by performing a prostate biopsy in a man suspected to be at risk of the disease. This is done using a needle biopsy device, which is passed into the prostate under ultrasound guidance, either via the rectum or through the skin behind the scrotum. These techniques need either local anaesthetic or sedation if done via the rectum or a general anaesthetic if done through the skin behind the scrotum (transperineal).

The use of prostate MRI imaging in the diagnosis of prostate cancer is increasingly being used. MRI may reduce the over-diagnosis and over-treatment of prostate cancer, as well as discover prostate cancers that are hard to reach with traditional techniques. 

Treatment

Once a cancer is diagnosed, your urologist will order scans to look for any evidence of spread outside the prostate. Prostate cancer will usually first spread to the lymph glands in the pelvis, or the bones of the lower back, pelvis or hips and femurs. Most urologists will therefore order a MRI scan to look at the lymph glands and a bone scan to look at the skeleton.

If there is no evidence of cancer spread (metastasis) on these scans, and depending on the age and PSA level of the patient, most patients will be offered treatment for significant cancers. This can take the form of:

• Surgery to remove the prostate - open, laparoscopic or robot-assisted prostate removal (radical prostatectomy)

• Internal radiation in the form of brachytherapy seeds placed directly into the prostate

• External beam radiation, in which the prostate is irradiated with daily sessions lasting 7 weeks, or 

• A combination of internal and external radiation therapy.

Treatment decisions are based on the risks and benefits of each procedure, which can be a complex decision, and best discussed with your urologist.

After treatment, prostate cancer can come back or recur in up to 15% of men. This is usually due to microscopic spread which was not visible on the staging scans, and can occur many years after the curative treatment occurred.  For this reason the PSA test is used as surveillance after treatment.

If the prostate is removed, the PSA should be less than 0.01 for the rest of the patient's life. In the case of radiation therapy, the PSA will drop quite low, usually less than 1.0 or even 0.5. It should then stay low for a long time. In either case if the PSA starts to rise it usually suggests a return of prostate cancer somewhere in the body. This can be in the prostate if still present, near where the prostate was or in the lymph glands or bones of the pelvis. In this scenario further staging scans are needed and treatment options are multiple and depend on numerous factors.