Preoperative irradiation and surgery for certain cancers.

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 enhancement 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. Randomized 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.