The treatment is called cryotherapy. Cryotherapy uses very low temperatures to freeze and kill cancer cells.

Secondary cancer of the liver is a very common problem and the usual treatment is chemotherapy. For some people with very few secondaries which are slow growing surgery might also be possible. As a consequence cryotherapy is seldom used in the UK although it may occasionally be recommended in certain special circumstances.

When it is used to treat secondary cancers (also called metastases) in the liver cryotherapy involves a period of preparation with special scan tests to pin point the position of the secondaries. This is followed by an operation during which insulated probes containing liquid nitrogen are inserted into the tumours to freeze them.

The operation is not without its hazards. Possible complications can be quite serious. They include bleeding into the liver, liver abscesses, low platelet counts in the blood (leading to a risk of bleeding), kidney failure and lung damage.

All this, means that cryotherapy is quite a complicated treatment and does carry some risks. Also, even though the operation can be repeated, it is still only possible to treat a limited number of secondaries in the liver - usually up to five and ideally far fewer. Unfortunately many people with liver secondaries will have more than 5 tumours in their liver. It is also more successful if the tumours are no larger than a few centimetres in diameter.

Even if it is 'successful' cryotherapy will not usually be a cure. This is because if a cancer has spread to form secondaries in the liver then very frequently there will be seedlings of tumour in other parts of the liver or elsewhere in the body - even if these are not apparent at the time. This means that even if cryotherapy controls the liver metastases then sometime in the weeks or months that follow other secondaries will appear at other sites.

Cryotherapy is not possible for the treatment of most secondary liver cancer. It is, however, available at specialist centres in the UK and it is a treatment option for carefully selected patients but it is only likely to be considered if the following conditions are met:

• normal chemotherapy has been tried but is no longer controlling the problem or chemotherapy has partially shrunk the secondaries and cryotherapy is offered to try and shrink them further.
• the patient remains otherwise fit
• there are only a few liver secondaries detectable
• the individual secondaries are not very large
• the cancer appears to be slow growing
• there are no obvious signs of active cancer elsewhere in the body.