Effects of the removal of the regional lymph nodes on the survival of mice bearing B16 melanoma or EAkR lymphosarcoma.

This work presents data concerning the effect of tumor excision accompanied or not by the removal of the regional lymph node (RLN) on the survival time of mice bearing the EAkR lymphosarcoma or the B16 melanoma. The operations were performed at various times to study this effect in relation to tumor size. Early tumorectomy, on day 6 for the EAkR lymphosarcoma, on day 10 for the B16 melanoma, significantly prolonged the survival time. The additional removal of the RLN abolished this beneficial effect. In the case of the EAkR lymphosarcoma. a beneficial effect on the survival time was, in contrast, observed after total excision of the tumor accompanied by RLN removal performed on day 8. The two surgical procedures were ineffective in increasing the survival time when they were applied after the 8th day for the EAkR lymphosarcoma and after the 10th day for the B16 melanoma. These results suggest that the preservation of the RLN may be favorable for the host, at least at an early stage of the tumor growth.