Abstract
Two tumors formed by metachronous metastasis in the lung were separately removed by surgery at an interval of one year and a half from a patient with rectal cancer. These tumors were transplanted into nude mice and their sensitivity to various anti-cancer agents was assessed in vivo. The chemosensitivity spectrum of one of these tumors resembled that of the other. When 10 tumors were serially transplanted into nude mice, most of them underwent acceleration of growth during the early passages. When two primary lung cancers were serially transplanted into nude mice, there was no evidence indicating changes in sensitivity to cytotoxic agents between tumors of passages 2 and 8 in one case and between tumors of passages 2 and 18 in the other. Accordingly, serial nude mouse passages does not appear to alter tumor susceptibility to anti-cancer agents. As described in our previous report, metastatic tumors resemble the corresponding original tumors in sensitivity to cytotoxic agents. Therefore, the results of previous chemotherapeutic trials on an original tumor or earier metastatic tumors should also apply to metastatic or subsequent recurrent tumors. Preservation of human tumor specimens by serial transplantation in nude mice makes it possible to assess the effectiveness of new and untested anti-cancer agents for cancer under treatment, opening the way for the development of more potent drugs.
