Metastasis of ocular and flank implants of the 13762NF mammary adenocarcinoma in syngeneic rats.

Solid fragments of a syngeneic tumor of low immunogenicity were implanted on the anterior surface of the iris or posterior surface of the cornea in young Fischer 344 rats. Growth and metastasis of these implants were examined and compared with those occurring following sc tumor implantation in the flank. Corneal implants did not grow well or metastasize. Iridial implants grew well, and tumor typically filled the eye within a few weeks. If tumor-filled eyes were left intact, all rats died or became moribund 7-9 weeks later. Metastasis was seen in the lungs (11/11), cervical lymph nodes (7/11), body wall (5/11), heart (4/11), kidney (4/11), and liver (3/11). Removal (enucleation) of tumor-filled eyes prior to spread to the orbit prevented the development of overt metastatic disease for 1-2 years (11/11). When healthy enucleated rats were necropsied 0 days to 26 weeks post enucleation, small nodules were seen in the lung (9/13), liver (3/13), or spleen (1/13). Nodules were not seen in rats that had been housed in our animal facility for 1-2 years (16/16), had eye surgery with tumor implanted on the posterior surface of the cornea (6/6), or had been subjected to the surgical procedures of corneal implantation and enucleation (3/3). When tumors were implanted sc, rats died after 6-7 weeks. Metastasis was seen in the lung (12/12), lymph nodes (12/12), spleen (1/12), and liver (1/12). Removal of very small flank tumors failed to prevent animals from dying 7-8 weeks later with pulmonary and lymph node metastasis (10/10). In summary, iridial implantation resulted in an altered pattern of metastasis. Animals that had iridial implants and enucleation failed to develop overt metastatic disease and had small nodules in the lung, liver, or spleen.