X-rays vs. carbon-ion tumor therapy: Cytogenetic damage in lymphocytes

Purpose: To measure chromosomal aberrations in peripheral blood lymphocytes from cancer patients treated with X-rays or carbon ions (C-ions). Methods and Materials: Blood samples from patients diagnosed for esophageal or uterine cervical cancer were obtained before, during, and at the end of the radiation treatment. The novel technique of interphase chromosome pain ting was used to detect aberrations in prematurely condensed chromosomes 2 and 4. The fraction of aberrant lymphocytes was measured as a function of t he dose to the tumor volume. For comparison, blood samples were also expose d in vitro to X-rays or to carbon ions accelerated at the HIMAC. Results: C-ions were more efficient than X-rays in the induction of chromos omal aberrations in vitro. In patients with similar pathologies, tumor posi tions, and radiation field sizes, however, C-ions induced a lower fraction of aberrant lymphocytes than X-rays during the treatment. The initial slope of the dose-response curve for the induction of chromosomal aberrations du ring the treatment was correlated to the relative decrease in the number of white blood cells and lymphocytes during the treatment. Conclusion: C-ions induce a lower level of cytogenetic damage in lymphocyte s than X-rays, reducing the risk of bone marrow morbidity. (C) 2000 Elsevie r Science Inc.