A new radiotherapy technique that can be carried out at the time of surgery and avoids long drawn out sessions of treatment may prove better at preventing the cancer returning in the breast and also bring breast conservation surgery within the reach of women in developing countries.
But, although intraoperative radiotherapy appears promising enough to be tested against traditional external beam radiotherapy in some cases, it is still far too early to be advised as standard treatment, Dr Emiel Rutgers told a news briefing at the 3rd European Breast Cancer Conference in Barcelona.
Reports on 3 studies - from the European Institute of Oncology in Milan (101 patients), the Institute of Oncology in Madrid (21 patients) and University College, London (26 patients) – are being presented to delegates at the conference. They describe how specially designed portable radiotherapy equipment delivers a concentrated electron beam to the area of the breast from which the tumour has been removed. The Milan Institute and University College now have randomised trials under way comparing introperative radiotherapy with conventional radiotherapy.
Dr. Rutgers, surgical oncologist at the Netherlands Cancer Institute in Amsterdam, said that traditional breast conserving surgery involved excision of the tumour followed by external beam radiotherapy of the whole breast. This can involve 20 to 25 separate visits to the radiotherapy department. It was usual now to give an extra boost to the site of the tumour either by external beam over 4 to 6 sessions or by implants. If implants were given after the course of radiotherapy that meant an extra hospital admission and anaesthesia for placing the needles (although this method had become less popular because of the problem of scar tissue after treatment). A major international trial comparing external radiation with or without a boost dose recently showed that a boost dose reduced the risk of recurrence in the affected breast. However, when relapses do occur they tend to be at the site of the original tumour. This has led doctors to investigate whether it would be better to irradiate only that part of the breast where the tumour occurred.
The Milan Institute used a mobile linear accelerator with a robotic arm to deliver electron beams through a Perspex applicator to the area around the ‘bed’ of the tumour. The cosmetic effect was very good and there have been no relapses within the 1 to 2 year follow up period of the early study. A phase III randomised trial comparing conventional and intraoperative radiotherapy, which began in November 2000, is expected to finish in 2005.
At the Madrid Institute, after a median follow up of 3 years, of the 81% of patients who were still alive none had suffered recurrence in the breast although 3 had developed lung or bone metastases. Again, cosmetic results were excellent and there were no side effects.
The University College study – known as Targit (Targeted Intraoperative radioTherapy) delivers the radiation by wrapping the targeted breast tissue round a spherical applicator. There had been no major complications and no local recurrences, although median follow up was still only 29 months. Their international randomised trial began in March 2000.
Dr. Rutgers warned: "We must be very cautious still about this technique. Not all the breast tissue is irradiated and we know from the international trial comparing ‘boost or no boost’ radiotherapy that around half of all recurrences do occur away from the original tumour bed. There is also a risk that low dose irradiation in the peripheral tissue may induce new cancers in the longer term or that concentrated high dose radiotherapy may lead to scar tissue and tissue death."
But, if the technique does live up to the hopes of investigators, there would be advantages.
"In addition to its ability to target the tissue that is most at risk of relapse, patients would not need long radiotherapy courses – one treatment and it’s over. Also, it may be cheaper and easier. These factors could be especially important for developing countries," said Dr Rutgers. "It means that many women in these countries, who currently have mastectomies because conventional longer term radiotherapy is not available or because they cannot make multiple visits for treatment, may for the first time have the option of choosing conservative surgery that will preserve their breasts."
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