Biological behavior of human malignant tumors grown in the nude mouse.

The biological behavior of a number of nude mouse-grown human epithelial tumors of different histogenetic background was studied. They included three transitional cell carcinomas and a mucin-producing carcinoma of the urinary bladder, two pancreatic adenocarcinomas, a colon adenocarcinoma, a breast ductal carcinoma, and an epidermoid carcinoma. Microinvasion was a constant finding in all tumors examined. All but one of the tumors studied showed macroinvasion and metastases. Tumors transplanted s.c. in the anterior aspect of the lateral thoracic wall metastasized primarily to the regional and mediastinal lymph nodes. In certain cases, systemic metastases were observed affecting the submaxillary, contralateral axillary, and inguinal lymph nodes. Lung metastases occurred through the lymphatic and hematogenous routes. It is concluded that the nude mouse-grown human tumors investigated in the present study show overt malignant behavior recapitulating the biological characteristics of the tumor of origin.