Abrogation of neovascularization in tumor-bearing mice: A putative explanation of concomitant resistance

The effect of a locally growing tumor on the neovascularization induced by sc neonatal testis implantation at a distant site was studied. A concomitant resistance (CR) inducing tumor, LB, was capable of inhibiting testis induced angiogenesis while a metastatic mammary tumor, C7HI, unable to generate CR, was not. Surgical extirpation of LB tumor reestablished the basal number of vessels, demonstrating the reversibility of the phenomenon. On the other hand, CR generated by a primary tumor against a distant secondary tumor implant was abrogated by the local presence of a capillary bed induced by a previous sc testis implantation. The inhibition of angiogenesis is postulated as a possible explanation for the antitumoral CR phenomenon, although the participation of other mechanisms cannot be discarded.