Chromosomal radiosensitivity and acute radiation side effects after radiotherapy in tumour patients - a follow-up study

Radiotherapists are highly interested in optimizing doses especially for patients who tend to suffer from side effects of radiotherapy (RT). It seems to be helpful to identify radiosensitive individuals before RT. Thus we examined aberrations in FISH painted chromosomes in in vitro irradiated blood samples of a group of patients suffering from breast cancer. In parallel, a follow-up of side effects in these patients was registered and compared to detected chromosome aberrations. METHODS: Blood samples (taken before radiotherapy) were irradiated in vitro with 3 Gy X-rays and analysed by FISH-painting to obtain aberration frequencies of first cycle metaphases for each patient. Aberration frequencies were analysed statistically to identify individuals with an elevated or reduced radiation response. Clinical data of patients have been recorded in parallel to gain knowledge on acute side effects of radiotherapy. RESULTS: Eight patients with a significantly elevated or reduced aberration yield were identified by use of a t-test criterion. A comparison with clinical side effects revealed that among patients with elevated aberration yields one exhibited a higher degree of acute toxicity and two patients a premature onset of skin reaction already after a cumulative dose of only 10 Gy. A significant relationship existed between translocations in vitro and the time dependent occurrence of side effects of the skin during the therapy period. CONCLUSIONS: The results suggest that translocations can be used as a test to identify individuals with a potentially elevated radiosensitivity

Chromosome analysis of the differential radiosensitivity of an Epstein-Barr virus (EBV)-transformed B cell line and B and T lymphocytes from the same blood donor.

PURPOSE: To date, simultaneously performed investigations on the differential radiosensitivity of an Epstein-Barr virus (EBV)-transformed B cell line as well as B and T lymphocytes of human peripheral blood are not available. Thus the aim of the present study was to fill this gap by directly comparing the corresponding dose-response relationships of dicentrics obtained in blood samples from the same donor. MATERIAL AND METHODS: Cell samples of whole blood or low passage cells of an EBV-transformed B cell line were irradiated by 120 kV X-rays in chambers tightly embedded in a polymethylmethacrylate phantom. Chromosome analysis was performed in phytohemagglutinin-stimulated T lymphocytes, in pokeweed mitogen-stimulated B lymphocytes and in the EBV-transformed B cell line. RESULTS: Based on dose-response relationships of dicentrics, different radiosensitivity values relative to T lymphocytes were found from 1.53-1.46 for the EBV-transformed cell line, from 0.76-0.80 for resting B lymphocytes and from 2.36-2.20 for cycling B lymphocytes within the dose range from 0.25-4 Gy. CONCLUSIONS: Owing to these different radiosensitivity values, care has to be taken when dose-response relationships of dicentrics determined in B cell lines are used in biological dosimetry to estimate any dose levels for radiation protection purposes