RACHEL HARRIS found she had breast cancer last autumn; several months later most of one breast was removed. Shortly afterwards, her consultant radiotherapist at a hospital in Hull recommended a three-week course of radiotherapy. Ms Harris, aged 45, was puzzled because a friend had just been given six weeks of radiotherapy following a similar operation. Even her consultant told her that most hospitals in Britain and Europe, and all those in the United States, recommended treatment over five to six weeks.

'When I asked the consultant about the difference, he told me it was because they didn't have the resources for longer treatment,' she recalls. It is a recent and good medical practice for consultations to be taped and the cassette given to the patient so that he or she can play it back later. Ms Harris was given the recording of her consultation. In it the consultant says: 'We couldn't possibly cope with six weeks, we've far too many patients.' He said it was standard practice at the hospital to have the shorter treatment and adds: 'In London and the south of England they use six weeks. Here in Hull we use three - there's a north-south divide.'

Ms Harris was perplexed by the situation. 'The treatment seemed resources led, not needs led. The next day I found myself wondering if the side effects were greater with the three-week treatment.'

Her confusion and concern are shared by many professionals within the health service. Despite radiotherapy having been a standard treatment for breast cancer for nearly 50 years, there is little detailed research into the benefits and disadvantages of different lengths of treatment.

A full treatment of radiotherapy can safely be spread over three weeks, and it is widely accepted that this is just as effective in killing off cancer cells, as four, five, or six weeks of less concentratated radiation treatment. What is disputed are the side effects. Many experts believe the short term treatment is inferior cosmetically.

Side effects include greater nausea and fatigue and, in a small number of cases, scarring of the breasts, which can become harder and occasionally painful. The skin can also change colour as blood vessels dilate.

Radiotherapy is frequently used to eliminate remaining cancer cells following surgery. But while it kills malignant cells, it also kills normal cells, although these recover more rapidly and completely than cancerous ones. Repeated doses of radiation are given with intervals between so that most of the healthy cells can recover while any cancer cells that survive are eventually killed off.

Dr Jeffrey Tobias, clinical director for cancer services at Middlesex Hospital, London, said: 'The issue is not just of how long one lives but of quality of life and that includes how one looks and feels. Most medical experts believe that the longer treatment is better cosmetically. This is based on experience, although there is no clinical research to prove this.

'I have seen patients who have had the three-week radiotherapy and I feel the result is not as good as the longer treatment. There is greater burning and the pigmentation is darker. Money is very tight and if we felt confident that three weeks was as good then we would change our system.'

The Royal College of Radiologists admits there is a general north-south divide between the lengths of treatment and believes this is partly cause by economics - there are fewer hospitals offering radiotherapy in the north and therefore a greater demand for the radiation machines. It is also partly tradition. The Christie trust hospital in Manchester trains radiotherapists to use three- week treatments. This has become accepted practice at the hospital and has been exported to other radiotherapy units throughout the country - particularly in the north.

Dr Jill Bullimore, Dean of Clinical Oncology at the college, says: 'We believe for best over-all treatment four to five weeks is probably ideal. I think a small number of women are probably going to get more scarring with three weeks. We are hard-pressed for money and have to keep the service on the rails.

'The divide is due to historic reasons and finance. But there's a compromise now - there's a tendency for four-week or four-and-a-half periods of treatment.'

Another reason that northern hospitals more often opt for the shorter treatment, she adds, is because many people in that part of the country had to travel long distances to receive radiotherapy and did not want the inconvenience and expense of five or six weeks of visits.

Dr Gerald Ribeiro, Clinical Onogologist at the Consultant Radiotherapy Unit at Christie hospital, concedes there is a 'marginal cosmetic advantage' for using longer radiotherapy treatment.

'The reason it started is because this is the only centre in the North-west and we get about 1,600 new breast cancer patients each year,' he says. 'We have had long experience using three weeks. It is expedient, since there was not enough machine time to treat patients longer. Each day we treat about 250 people. The machines here are working at full capacity all the time.

'The only difference (with the three-week treatment), if there is one, is a slight cosmetic one.' Dr Ribeiro agrees there is slightly more thickening and hardening of the breasts. He stresses, however, that there is no research to prove the three-week treatment is inferior.

Dr Richard Ashford, consultant radiotherapist at Mount Vernon trust hospital in Northwood, Middlesex, where the three- week treatment plus a one-week boost is usually offered, believes there is no 'perceived' difference between the different doses. 'My reason for using three weeks are not based on economics, but on sound medical practice,' he says.

After a mass of contradictory advice about radiotherapy, Ms Harris felt disillusioned and was concerned about the side effects, particularly after talking to other patients. A consultant in London told her that the only way to get the longer radiotherapy treatment would be to pay for it privately. St Bartholomew's hospital quoted her pounds 5,000-10,000.

When she decided to withdraw from the three-week treatment after two sessions, her surgeon insisted on further surgery to remove any remaining cancer cells that the radiotherapy would normally kill. 'It was an old-fashioned operation - a much more drastic alternative,' she says. 'I'm still not sure I made the right decision, but I decided that the possible costs of the radiotherapy outweighed the benefits.'

The failure to carry out the research and to reach a consensus is even more extraordinary given that 15,000 British women die from breast cancer each year - the UK has the worst death rate in the world from the disease - and that 24,500 new cases are diagnosed annually.

Rachel Harris is a pseudonym.