Prediction of radiation-induced toxicity by in vitro radiosensitivity of lymphocytes in prostate cancer patients

To identify predictive assays for radiation-induced toxicity in prostate cancer patients. Patients have been surveyed prospectively before and up to 16 months after radiotherapy using a validated questionnaire. Subgroups of 25 patients with minor and larger score changes, respectively, were selected for γ-H2AX, G2 and Annexin V assays. A significantly higher spontaneous chromatid aberration yield (HR: 1.46 [95% CI: 1.02-2.09]; p = 0.04), higher levels of early apoptotic (HR: 1.12 [95% CI: 1.01-1.24]; p = 0.04) and late apoptotic and necrotic (HR: 1.10 [95% CI: 0.99-1.23]; p = 0.08) lymphocytes 24 h post-irradiation were found in patients with a bowel bother score decrease greater than 20 points more than 1 year after treatment. Chromatid aberration and apoptosis/necrosis assays appear to be suitable for the prediction of radiation-induced toxicity.