Xenograft growth and histodifferentiation of squamous cell carcinomas of the pharynx and larynx.

The potential for growth in a xenogeneic host and the pattern of histodifferentiation was examined in 56 human squamous cell carcinomas of the pharynx and larynx transplanted to nude mice. Among these 56 transplanted tumors, 13 of 36 primary and 12 of 20 metastatic tumors were found to be tumorigenic in nude mice. Eleven of 24 pharyngeal and 14 of 32 laryngeal tumors grew in nude mice. The dynamics of transplanted tumor growth in the surrogate host took place independent of the tumor grade and site of tumor origin. Transplanted tumors exhibited a higher mitotic index compared with the original tumors. Each passage of a tumor line resulted in most of the xenograft tumors exhibiting an increased degree of differentiation without invasion of host tissues. No difference was observed between patients who engrafted tumors in the xenograft model and those who did not with respect to tumor biology or clinical findings, including survival.