Clinical evaluation of an in vitro test for radiosensitivity of leukemic lymphocytes.

By ROBERT SCHREK, STANLEY L. LEIThOLD, IRVING A. FRIEDMAN AND WILLIAM R. BEST A PREVIOUS PAPER described a slide-chamber method for the measurement of the radiosensitivity of lymphocytes from leukemic patients.1 The method was used to study 31 patients with chronic lymphocytic leukemia or with lymphosarcoma in leukemic phase.2 The patients showed considerable variability with respect to the radiosensitivity of their blood lymphocytes. Of particular interest were a few patients with lymphocytes which were resistant to irradiation with 1000 roentgens. This high degree of resistance was quite impressive since the lymphocytes of other leukemic patients and of non-leukemic individuals showed significant responses to dosages as low as 2 roentgens. An evaluation of the clinical significance of the slide-chamber method requires the determination of the correlation of radiosensitivity of the leukemic lymphocytes in vitro with clinical response of the patients. Unfortunately, this is a difficult problem in view of the many uncontrolled variables in a clinical study and because of the lengthy period required to collect sufficient patients and study their clinical progress. The clinical histories of 80 leukemic patients were thoroughly reviewed. In this report we will consider a few objective clinical findings of 19 patients with radioresistant lymphocytes and 61 patients with sensitive cells.