Zapping the cancer cells

Last week a report from the Royal College of Radiologists confirmed that the misadministration of radiotherapy could lead to inappropriate doses of radiation being received by cancer patients, with hundreds of women suffering from breast cancer receiving compensation from the Government.

Cancer patients are normally given radiotherapy five days a week over a six-week period, with weekends off. But when 36-year-old Alison Peach was diagnosed as having neck and throat cancer two years ago, she was given the option of a far more aggressive regime after surgery to remove the primary tumour: radiotherapy three times a day for 12 consecutive days. Alison, who has two daughters, agreed to the 12-day regime because "it was so convenient. Christmas was looming and I thought I'd get it over and done with." She developed a badly ulcerated mouth and sore throat from the radiation, but two years on she has made a complete recovery. "When you've got cancer, you just want to have the treatment and start getting well again," says Alison.

The new, more intensive regime is called Chart (Continuous Hyperfractionated Accelerated Radiation Therapy). Although not yet widely available, it has already achieved the first improvement in lung cancer survival rates for 20 years.

A five-year trial of Chart at Mount Vernon Hospital, Middlesex, involving 563 lung cancer patients, showed that those treated with Chart were still alive after two years, compared with only 20 per cent of those receiving conventional radiotherapy. A second trial, which focused on 918 patients with head and neck cancer, showed that treatment with Chart achieved "total tumour clearance" in 60 per cent of patients, compared with 40 per cent in patients receiving conventional therapy.

Usually, radiotherapy is given to cancer patients in a dose of 2Gy (a Gy is a unit of radiation) once a day from Monday to Friday over a period of six to seven weeks. This is thought to give normal cells a chance to recover and means cancer sufferers can be treated as outpatients.

But according to Professor Stanley Dische, former clinical director of Mount Vernon's cancer centre, who co-ordinated the head and neck trial, these gaps in treatment allow remaining cancer cells a chance to regroup and proliferate. "Some cells within them have a capacity to double their number in up to five days," he says. "The evidence now shows that while a tumour is being treated it is also growing, so as you kill off tumour cells, others will be produced."

Professor Dische says that shortening the interval between doses means cancer cells have less time to repopulate. But so far, attempts to use more intensive radiotherapy treatment have failed because of the damage they do to normal tissue. Chart uses 1.5Gy doses of radiation three times a day for 12 consecutive days - with a gap of six hours between doses to allow normal cells to recover.

Chart has its disadvantages: side-effects such as a sore throat tend to be more troublesome. "This tends to get a little worse in the short term but heals more quickly than with the six-week treatment," says Dr Michael Henk, adviser to Chart and a consultant oncologist specialising in head and neck cancer at the Royal Marsden Hospital, London. And of course, patients have to stay in hospital.

Dr Henk says one important advantage of Chart is that it is more convenient and less demoralising, especially for elderly patients. "They tolerate it better. The treatment is over before the side-effects become troublesome."