Firstly it may be helpful to know that most skin cancers can be successfully treated. There is a 95% cure rate for the two most common types, which are rodent ulcers (or basal cell carcinomas/BCCs) and squamous cell carcinomas (SCCs).

However, occasionally these cancers can spread in an irregular and unpredictable way. Mohs' surgery is a type of surgery for skin cancer that enables the surgeon to remove all of the cancer, in several stages, without removing too much healthy tissue. This type of surgery is also called ‘micrographic surgery’, which means that a microscope is used to examine what is being done during the procedure.

Frederick Mohs was an American surgeon who, during the 1940s, pioneered this new type of surgery. In Mohs’ surgery, the tumour is removed piece by piece. Each piece removed is microscopically examined straight away. If examination under the microscope shows that some cancer might still be present, then more tissue is removed and examined. This process continues until there are no signs of any cancer cells left.

This technique minimises the removal of healthy skin while making sure that the cancer has all been taken away. Mohs' surgery is particularly useful for basal cell cancers that have come back in the same place, or where the doctor thinks that the cancer has begun to spread into the surrounding area. It is also sometimes used for skin cancers on the face (to minimise the effects of surgery) or for large skin cancers. The technique can also be used to treat skin tumours that come back after normal surgery or radiotherapy.

The procedure is often done under local anaesthetic and you are usually allowed to go home the same day. However, if you are having a large tumour removed, you may also need to have a skin graft or flap to cover the wound and so may have to stay in hospital for up to four days. This is very specialist surgery and is only available in a few hospitals in the UK. Your specialist may refer you to one of these centres if he or she thinks that this technique may be necessary in your case.