The role of radiotherapy in the management of cancer--an overview.

Artificial X-rays were first produced in Germany in 1895 and used for cancer almost immediately. During the century since this remarkable discovery, radiation therapy has now become the most imporantant non-surgical modality in cancer: over 50% of all cancer patients now receive radiotherapy at some point during the illness. Radiation therapy has increasingly replaced surgical resection for primary control of a variety of solid tumours, particularly where surgical excision is accompanied by severe long-term tissue loss or psychological morbidity. Frequent examples include cancers of the breast, head and neck (especially larynx, naso- and other pharyngeal sites), and locally advanced cancer of the cervix. Combinations of surgery and radiotherapy are increasing used, for example in the preferred management of most cancers of the breast, by wide local surgical excision, breast preservation and postoperative radiotherapy. In rectal carcinoma as well, there is clear evidence of survival improvement in locally advanced cases when surgical excision is followed by routine pelvic irradiation. In other circumstances, radiation is routinely combined with chemotherapy, as for example in the standard management of small cell lung cancer. Anal carcinoma is also best treated by radical radiochemotherapy, avoiding surgical excision (with permanent colostomy) in the majority of patients. In both the developed and developing world, these are all common tumours, with the result that in 1990, almost half a million patients were treated with radiation therapy in the United States of America. Recent technical advances, both in imaging and therapy beam precision, have greatly improved the therapeutic ratio and accuracy of modern radiotherapy. Radiation therapy continues to progress on a rational scientific basis, with a secure clinical role for the foreseable future.