Neoplastic Sequelae Following Subcutaneous Implantation of Mice with Rare Earth Metals 1

Summary

Subcutaneous implantation of 118 CFW mice with the rare earth metals gadolinium and ytterbium was followed by the development of sarcomas at the implantation site in 12 (10.2%) of the treated mice. Pulmonary metastases occurred in 4 of the 12 cases. Comparable sarcomas did not occur in sham-injected control mice, nor were they encountered at sites other than implantation and metastasis. These results do not indicate the associative mechanism, but it would appear that these metals induce sarcomas or promote their formation by uncovering latent oncogenic factors.