Failure to cure cancer by surgery is caused by inability to remove all local extensions of the lesion or from prior or synchronous dissemination of tumor cells. Laboratory evidence has suggested that preoperative irradiation of the primary tumor can increase cure rates. In the clinical realm, the efficacy of preoperative irradiation appears to vary with specific tumors, Lung cancer shows no improvement in survival. Cancers of the bladder and breast may show e n hancement of cure rate. Data indicate that cancer of the rectosigmoid does benefit from preoperative therapy. Adherence to important factors of dosage and timing of operation is necessary to prevent undesirable complications. Random ized clinical trials are needed to establish the efficacy of this combined modality treatment system. This is particularly true since both these modalities can be applied on a wide-scale basis if beneficial effects are conclusively demonstrated.
Cancer 35:84-90, 1975.
URGERY HAS REACHED ITS LIMITS OF APPLI-S cability in the treatment of cancer. This concept is supported by data indicating a plateau has been achieved in survival rates for patients treated by operation alone. Until a diagnostic modality is available which will detect cancer in its earliest stages, thus making surgical cure probable, it would appear necessary to supplement surgical effects by another treatment modality if patient survival rate is to be improved within the near future. This paper will consider the use of preoperative irradiation and surgery as one such combined modality approach. By a selfadopted convention, this paper will be restricted to cancer of the breast, lung, bladder, and rectosigmoid, and will not review the experiences with tumor sites which are being considered specifically in other papers in this seminar .
BIOLOGICAL BASIS FOR PREOPERATIVE IRRADIATION
Theoretical Considerations Malignant tumors spread by direct invasion, lymphatic extension, and hematogenous me-