Tumor clonality: research and clinical aspects.

Except for the rare exclusions, all sporadic tumors originate from the only cell. However, the majority of malignant cells proper, constituting the tumor, demonstrate significantly heterogeneous morphology and physiology, differing by mobility, expression profiles, receptor presentation on cell surface, proliferative and angiogenic potential. The data presented in this report confirm the existence of intratumorous clonal heterogeneity. Potential biological and clinical significance of clonal heterogeneity and the existence of genetic differences between the primary tumors and their metastases and the effects of clonal tumor heterogeneity on the metastatic process are discussed.