Susanne Greenstein, at 44, was unprepared for the news that she had breast cancer. She was even more shocked to hear that, because the tumour was large and sited behind the nipple, her only option was a full mastectomy. Six months later, she still had her breast and the tumour had been eradicated. Today she is free of the disease, thanks to a a new electric breast pump for anti-cancer drugs developed at London's Royal Marsden Hospital.

Mrs Greenstein was one of 50 women to take part in a pilot study of the pump at the Royal Marsden. The findings could have a revolutionary effect on the treatment of breast cancer. Because of its slow-release mechanism, patients who wear the pump can receive anti-cancer drugs at a dose 500 per cent stronger than conventional chemotherapy, without suffering the usual side-effects such as nausea and hair loss.

Dr Ian Smith, head of medicine for the Cancer Research campaign at the Marsden, has spent his career trying to find alternatives to mastectomy. For large cancers of the breast, conventional treatment is still radical surgery followed by a course of chemotherapy. But in 1986, Dr Smith's team began to reverse the conventional treatment by offering drugs before surgery, in the hope that the drugs would shrink the tumour sufficiently for the surgery to be less mutilating.

At first, Dr Smith found that simply reversing the order of conventional treatment was unsatisfactory. But in 1991, he tried administering the anti- cancer drugs through a small electric pump, designed in the US more than 10 years ago. He realised he might be able to save women's breasts as well as their lives. 'The concept was to treat women with large breast cancers who would otherwise be offered mastectomy,' he says. 'In these cases it would not be possible for the surgeon to do conservation work.

'We had originally hoped to reduce the tumour to enable any residual amount to be removed in a small operation. But, when using the pump, in more than half of our patients the cancer disappeared completely from the breast with drug treatment alone.'

He presented the findings of his team's pilot study at an international Breast Cancer Conference in Texas last month. During a two-year trial, the 50 selected women wore the infusion pump 24 four hours a day for up to six months, and 86 per cent were able to avoid the need for mastectomy. The pilot is completed and 300 more patients will now be included in a large-scale trial.

Mrs Greenstein contacted the Marsden on the suggestion of the Breast Care and Mastectomy Association. She was asked by one of the doctors if she wished to take part in the pilot study. 'In all the time I was treated there, everyone was so positive,' she recalls. She began treatment with the pump at the end of April, four weeks after her tumour was first diagnosed and she had been told she would lose a breast.

The pump, which runs on batteries, looks like a portable cassette player and is strapped round the waist. 'I called it my Walkman,' says Mrs Greenstein. 'People used to ask me if it was a purse or a camera.' The pump is attached to a long tube, called a Hickman line, which is inserted under the skin through an incision in the chest. The tube feeds a constant stream of Flourouracil, an anti-cancer drug, into a vein near the collar bone, from where it circulates the body.

Mrs Greenstein found wearing the pump no problem at all and says it causes neither pain nor discomfort. 'At first I wondered how I was going to cope with this thing on me,' she says. 'When I lay in bed I could hear it whirring. But you get used to the noise. Soon you don't notice it's there.

'Some women wore their pumps under their clothes, but I felt more comfortable with mine on the outside. I felt if I hid it, it would look bulky and more noticeable. It became a part of me, like another limb.'

Mrs Greenstein was shown how to clean and maintain the pump, and twice a week was visited by a district nurse. At regular trips to the hospital, she and her husband Phillip could watch the tumour shrinking on an ultrasound monitor. 'After only one month,' she recalls, 'it was about half its original size.'

An extra boost of drugs had to be injected at three-weekly intervals, when side effects are usually at their worst; but Mrs Greenstein used the latest techniques to ease her discomfort. 'I wore a helmet made of ice packs to stop me losing all my hair,' she says. 'These things are very important, they have to do with self-esteem.'

After six months of wearing her breast pump, her tumour was hardly measurable. She needed only minor surgery to remove the remainder, leaving her breast intact. She has tiny scars from this operation and from the site where the Hickman line entered her chest.

Mrs Greenstein is now free of the disease, although she is prescribed tamoxifen, a drug that reduces levels of oestrogen, implicated in breast cancer. She is also having a course of radiotherapy to reduce the risk of recurrence.

Initial costs of the infusion pump and drugs are pounds 3,800 compared to pounds 1,500 for conventional drug treatment. But this is before the costs of surgery are taken into account; as production of the pumps become cheaper, so will the cost of the treatment. And that is before calculating the emotional cost of mastectomy.

'We can say that the days of mastectomy as a front-line treatment are nearly over,' says Dr Smith. 'Mastectomy will become a much more specialised surgery for a few selected patients whose cancer does not respond to chemotherapy. At least women will know that if they have to have the breast removed, it will be absolutely essential.'

Dr Smith finds it 'ironic' that this exciting development comes from a hospital that is under threat of closure. The Institute of Cancer Research at the Marsden is western Europe's largest cancer centre.

'Our detractors say we offer nothing new,' he says, 'and yet this is just one area where we are pioneering new treatment.'

Breast Care and Mastectomy Association helpline: 071-867 1103.

(Photograph omitted)