Cancer growth fraction

The rate of growth of human and experimental cancers is initially quite rapid (exponential) and then slows until a plateau is reached. The decrease in growth rate with increasing tumor size is related both to a decrease in the proportion of cancer cells actively proliferating (termed the growth fraction) and to an increase in the rate of cell loss due to hypoxic necrosis, poor nutrient supply, immunological defense mechanisms, and other processes. 

Effective for high growth fraction malignancies, e.g., hematoiogic cancers... 

The cell-kill hypothesis states that the effects of antitumor drugs on tumor cell populations follow first-order kinetics. This means that the number of cells killed is proportional to the dose. Thus, chemotherapy follows an exponential or log-kill model in which a constant proportion, not a constant number, of cancer cells are killed. Ilieoretically. the fractional reductions possible with cancer chemotherapy can never reduce tumor populations to zero. Complete er ica-tion requires another effect, such as the immune response. A modified form of the first-order log-kill hypothesis holds that tumor regressions produced by chemotherapy are de-.scribed by the relative growth fraction present in the tumor at the lime of treatment This idea is consistent with the finding that very small and very large tumors are less responsive than tumors of intermediate size. ... 

Examples (a) Cancerous tumors having high growth fractions which are foimd to give adequate response to chemotherapy are, namely Hodgkin s disease, Burkitt s lymphoma, Wilm s tumour, acute leukemia in children, choriocarcinoma, chronic myelogenous leukemia, lymphocytic leukemia, and breast cancer. 

Efficacy of antineoplastic drugs is increased significantly in early treatment of newly developed small cancerous tumours having relatively higher growth fractions. 

The unbound fraction of the epidermal growth factor receptor tyrosine kinase inhibitor gefitinib has been extensively studied in cancer patients [39]. The drug was found to bind to serum albumin, oq-acid glycoprotein, and red blood cells with a mean unbound fraction of 3.4% which was constant over 28 days of dosing. Unbound fraction ranged from 2.2% to 5.4% and was inversely correlated with pre-treatment levels of oq-acid glycoprotein. 

Chinese hamster ovary cells overexpressing the prolactin receptor, was active . Protein synthesis stimulation. Sterol fraction of the extract, in cell culture at a concentration of 25 (xg/mL, produced weak activity on CA-LNCAP. A concentration of 50 (xg/mL was active on CA-PC3 h PSA production inhibition. Ethanol (70%) extract of PC-SPES (a Chinese herb combination of chrysanthemum, dyers woad, licorice, reishi, san-qi ginseng, rabdosia, saw palmetto, and baikal skullcap), in cultured prostate cancer cell line at variable doses for 24 hours, produced a significant effect in supressing cell growth in all the cell lines h... 

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