Cell proliferation kinetics in tumors after treatments.

Analysis of data on cell reproductive death, cell proliferation kinetics, tumor volume responses and tumor eradication probability after single and fractionated doses of radiation given to experimental tumors, can yield several conclusions which may be relevant for the interpretation of clinical data: 1. considerable differences are observed among various cell types with respect to intrinsic radiosensitivity, but no specific differences are demonstrated for cells from tumors as compared to cells from normal tissue; 2. cell survival curves measured by in vitro cloning techniques for cells irradiated in an experimental rat rhabdomyosarcoma are consistent with the observed probability of tumor eradication, and 3. after a sufficiently large dose of radiation and after two weeks of fractionated treatments, important changes in cell proliferation kinetics have been observed with respect to cell cycle, cell production rate and cell loss rate, which may significantly influence the time of recurrence as well as the probability of attaining tumor eradication.