Cryosurgery or cryotherapy is the use of extreme cold to freeze and destroy cancer cells.

Cryotherapy has been a treatment for prostate cancer for many years. It has mostly been used to treat men whose cancer came back in the prostate after radiotherapy. However, until recently, problems with side effects have stopped it being widely used. However advances in technology have lead to improvements in giving the treatment and the National Institute for Clinical Excellence (NICE) have now approved cryotherapy as a treatment option for

• early prostate cancer that is confined within the prostate gland
• prostate cancer that has come back after previous treatment but has not spread outside the prostate.

This means that experts have judged cryotherapy is safe enough and works well enough in these situations for it to be made available on the NHS.

There are still aspects of cryotherapy the experts would like to know more about and so research is continuing. The NICE guidance says that

• there is still not enough evidence to be sure how effective it is in the long term (over 10 years or more)
• it's not clear what effects having the procedure may have on a man's quality of life.

Cryotherapy can be given under a general anaesthetic or under a spinal anaesthetic (an epidural), which numbs the area around the prostate.

Before the freezing treatment begins, a catheter is put into the bladder. Warm fluid is circulated through the catheter during cryotherapy. This is to protect the urethra (the tube that carries urine from the bladder through the penis) from being damaged by the cold.

Several small probes are then inserted into the prostate gland through the skin that lies between the scrotum and the anus (perineum). These will give the cryotherapy. Probes that monitor the temperature of the prostate may also be put into the area. A trans rectal ultrasound scan is used to guide the probes to the best position.

Once they are in position, freezing argon gas is circulated through the probes. This reduces the temperature of the prostate cancer tissue to less than -40C causing the cells to die. A treatment may take around 2 hours and may involve repeated freezing and thawing of the tumour cells.

There maybe some pain in the rectal area immediately after treatment. This can usually be relieved with painkillers. There may also be problems passing urine and, to prevent this, a urinary catheter is usually left in place for a week or so.

The most common side effects after cryotherapy are

• problems getting an erection (impotence) - this occurs in up to 72% of men in some studies
• urinary problems - occur in up to 1% - 18% of men

For some men, impotence may only be a temporary problem but it can also be permanent. Urinary problems may include incontinence, or difficulty passing urine due to a narrowing of the urethra. Sometimes this may need a minor operation to stretch the urethra or to remove some of the prostate. A rarer complication of cryotherapy, affecting about 1 or 2 men in every 100 men, is the formation of an opening between the rectum and the urethra (called a fistula).

Cryotherapy is only available at a few centres in the UK, and the technology is still developing. For most men the current treatments of surgery, radiotherapy or hormone therapy give the best chance of success. However, for a few men cryotherapy may give an extra benefit. Your specialist will be able to talk through with you whether this treatment may be suitable for you.