Experimental studies on the incidence of metastases after failure of radiation treatment and the effect of salvage surgery.

FSaII, a spontaneous fibrosarcoma, and SCCVII, a spontaneous squamous carcinoma, were studied as early generation isotransplants in the right leg of C3Hf/Sed mice. Animals successfully treated, in respect to local control by surgery alone for 6 mm diameter tumors, had an incidence of distant metastases of 2.6% for the FSaII, and 8% for the SCCVII. For 12 mm tumors the incidence of metastases was 14.3% and 41%, respectively. Animals successfully treated with radiation alone for 6 mm tumors had an incidence of distant metastases of 3.1% for the FSaII, and 6.9% for the SCCVII. Animals that developed local recurrence after radiation therapy were treated with salvage surgery when the recurrent tumor was either 6 mm or 12 mm. For those successfully treated the incidence of metastases was 12.5% for the FSaII, and 43% for the SCCVII when salvage surgery was performed on 6 mm tumors. When surgery was delayed and performed on 12 mm tumors, the incidence was 46.6% and 70.3%, respectively. The results indicate that after failure of radiation treatment there is a high incidence of metastases from the recurrent tumors. The incidence, however, can be reduced considerably by carrying out early salvage surgery.