Adjuvant irradiation for breast cancer. Treatment plans need to be made with better anatomical information.

Editor—Kunkler's editorial on adjuvant irradiation for breast cancer addressed an important problem.1 More and more patients of all age groups with potentially highly curable disease are being treated with both adjuvant chemotherapy and radiation. It is therefore most important that the treatment should be given in the safest possible manner while maintaining its therapeutic advantage. Increasingly, people recognise that radiotherapy can improve survival in breast cancer, and practitioners are becoming aware not just of the cardiac morbidity that occurs but also of the cardiac mortality. To investigate the magnitude of these problems we have undertaken a series of magnetic resonance scans on patients before radiotherapy planning and treatment. The advent of magnetic resonance imaging has allowed us to quantify the accuracy with which radiotherapy treatments are being delivered in breast cancer. The architecture of our magnetic resonance scanner is open and allows patients to be scanned in the treatment position. Magnetic resonance images have the advantage over other imaging techniques in that they clearly show tumour, tumour bed, and lymph nodes. Because of the limited resource, patients were chosen if they were to have radiotherapy on the left side or if they were to have extensive radiotherapy, including of the nodes, to the right side. We have now scanned 600 patients; preliminary analysis on the first 200 clearly shows that, in at least 30% of cases, conventionally planned treatments would have been suboptimal. As far as the heart is concerned, more than 80% of the left sided treatments would have irradiated a considerable fraction of cardiac tissue, quite often in the territory of the left anterior descending coronary artery. A finding of potentially greater importance was that the tumour bed was frequently missed. In the first 200 patients more than 30% would have had complete or partial treatment failure. In over 90% of the patients requiring adjacent nodal irradiation the entire cervicoaxillary chain below the clavicle failed to be encompassed. Despite the lack of precision of conventional treatment planning that we have shown, radiotherapy does improve survival. It is therefore reasonable to expect that if future treatment plans were made with the benefit of adequate anatomical information, its efficacy would be greatly enhanced. In addition, cardiac morbidity and mortality would be reduced.