title: Heterogeneity of tumor cells.
abstract: Investigations of cell clones isolated in vitro, or selected in vivo, have shown that tumor cell populations are heterogenous. The isolated cell clones or cell subpopulations originating from a single tumor may differ in a variety of biological and biochemical characteristics. Genetic lability and selective pressure are the most probable mechanisms by which a proliferating tumor cell population becomes heterogenous. Differences in drug sensitivity of cell subpopulations within a tumor represent a major limitation in tumor sampling procedures for tests predictive of effective chemotherapy. Different drug sensitivity was found when comparing human cancer cell samples from a primary solid tumor with those obtained from ascites, different metastatic nodes, or even in samples from different areas within the same tumor.
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002469:Cell Separation; D002478:Cells, Cultured; D004273:DNA, Neoplasm / Q000096:biosynthesis; D009369:Neoplasms / Q000188:drug therapy / Q000473:pathology*; D009588:Nitrogen Mustard Compounds / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D009588:Nitrogen Mustard Compounds; C009802:2,2',2''-trichlorotriethylamine