Christopher Moore's cancer was finally diagnosed in January. The biopsy findings did not surprise him. He had feared that the scaly, inflamed mass in the bowl of his left ear was a cancer. The hospital had thought it was some sort of wart.

Over a period of eight years it had been treated with liquid nitrogen, a therapy commonly used to freeze and kill the cells of pre- cancerous lesions. But the condition worsened and Mr Moore, a retired Royal Air Force officer, sought a second opinion. A few days later a basal cell carcinoma was confirmed.

By now the cancer had spread over the bowl of the ear and urgent surgery was necessary. Surgeons normally take out about four millimetres of healthy tissue around a basal cell carcinoma as a safety margin just in case any cancerous cells have been left behind.

In Mr Moore's case, the biopsy had shown cancer at four different points in his ear and it was impossible to tell where the diseased tissue began and where it ended. As a result he stood to lose most of his ear to the surgeon's knife.

But his dermatologist knew of a new technique, already well established in the United States but more recently introduced here, which could safely remove the cancer and leave the ear intact.

Mr Moore was referred to Dr Nicholas Telfer, a dermatologist specialising in skin surgery at the Skin Hospital, Manchester, who runs one of only three clinics in the UK that use 'Mohs Technique'. The others are at St Thomas' Hospital, London, and the John Radcliffe Hospital, Oxford.

The technique, named after its inventor, an American surgeon called Dr Frederic Mohs, allows skin cancers such as Mr Moore's to be removed accurately under local anaesthetic without the necessity of destroying healthy tissue to create a safety margin. It is done with no more inconvenience to the patient than a visit to the dentist. This is because the cancerous tissue is sliced off horizontally, a thin sliver at a time. The patient then sits in the waiting-room while each sliver is immediately analysed in the next-door laboratory.

Dr Telfer says: 'Mr Moore had a very nasty cancer. It was impossible to see where the boundaries were and had he been treated conventionally he would certainly have lost most, if not all, of his ear. Using this technique, we were able to remove the cancer without the blind sacrifice of healthy tissue.'

Dr Telfer, who runs the clinic two days a week in addition to his normal hospital duties, says he is inundated with patients referred by dermatology colleagues. 'The Mohs technique allows you to work on areas which would be very disfigured by conventional surgery, such as eyelids, nose, ears and lips. We can remove the tumour and still save most of the normal tissue.'

He says Mohs is an extremely cost-effective treatment. 'The only other two forms of treatment that offer any sort of decent cure rate are plastic surgery and radiotherapy. Plastic surgery, unlike Mohs, is an in-patient procedure with at least one night's hospital stay. It needs a theatre, a full team and pathology back-up. With Mohs, I do the anaesthetic, the surgery and read the pathology.

'Radiotherapy is unpleasant, expensive and requires multiple visits by the patient. In terms of both cost and ease of treatment, Mohs is simply streets ahead of both alternatives.'

There are three types of common skin cancer: basal cell carcinoma, squamous cell carcinoma and melanoma, all associated with exposure to sunshine. Together they are the second commonest form of cancer in the UK with 40,500 new cases a year, 36,000 being non-melanomas.

Plastic surgeons are cautious about the Mohs technique. Mr Clive Orton, consultant at the Christie Hospital, Manchester, says 'Mohs is an excellent technique for a small number of patients. Many dermatologists believe it should be used for a wide range of cases but I believe the claims made for it are over the top.' He says he would be unhappy to use it for squamous cell skin cancer, which is more aggressive.

There is agreement that the Mohs technique is not suitable for melanoma, which spreads too fast and must be surgically removed with lots of safety margin.

The cure rate by Mohs surgery is greater than 98 per cent for previously untreated basal and squamous cell carcinomas and better than 93 per cent for recurrent tumours. Mr Orton says that conventional treatment has a 97 per cent cure rate for basal and squamous cell cancers - that is, being cancer-free after five years.

On removal, the sliver of tissue is marked with different colours so that the surgeon and laboratory team can orientate themselves. For example, blue indicates the top of the specimen in relation to the patient's face and so forth.

The standard method of processing a specimen of removed tissue involves examining random slices. This means that a large part of the tissue sample is not examined and cancerous cells can be missed.

With the Mohs technique, however, the sample is flattened, frozen and dissected horizontally allowing the whole of its underside and perimeter to be microscopically examined. If cancerous cells are found in these areas it means there is still cancer left behind at this spot in the patient.

If this is the case the patient returns to the operating room, the local anaesthetic is topped up and another slice taken. This is then analysed and so on until no more cancer is discovered.

Dr Telfer went to the US to train in the technique before returning to start his NHS-funded clinic in Salford. In Mr Moore's operation he cut away the cancer, layer by layer. It took three sessions of about 15 minutes each and while Dr Telfer examined each layer in the laboratory, Mr Moore sat in the waiting room. He said: 'Actually there was no discomfort at all. I was there for about four hours and most of the time was spent waiting.

'Dr Telfer was extremely good about explaining what they had found in the laboratory and exactly what they were doing and why. When it was finished my ear was dressed and I went home.

'The cancer has been removed and I am hopeful that it will not come back - and I still have my ear. The skin is regrowing and it is almost as good as new. I am very, very relieved.'

Leaflets from the Imperial Cancer Research Fund, PO Box 123, Lincoln's Inn Fields, London, WC2A 3PX, 071-242 0200.