Enhanced in vitro radiosensitivity of skin fibroblasts in two patients developing brain necrosis following AVM radiosurgery: a new risk factor with potential for a predictive assay.

Abstract

Radiosurgery is an effective treatment for arteriovenous malformations (AVM) with a low risk of developing brain necrosis. Models have been developed to predict the risk of complications. We postulated that genetic differences in radiosensitivity may also be a risk factor. Fibroblast cultures were established from skin biopsies in two AVM patients developing radiation necrosis. The results of clonogenic survival assays were compared to a parallel study with two groups of cancer patients treated with radiation: 1) patients without late side effects; 2) patients experiencing severe late sequelae. The survival fraction at 2 Gy (SF2) of the 2 AVM patients was 0.17 (0.14-0.19) and 0.18 (0.14-0.22). The SF2's of the cancer patients ranged between 0.25-0.38 (mean = 0.31) for the control group, and between 0. 10-0.20 (mean = 0.17) for the hypersensitive group. The SF2's of the AVM patients who developed brain necrosis were comparable to that of the hypersensitive group (p = 0.85) but significantly lower than the control group (p = 0.05). The two patients who developed radiation necrosis demonstrate increased fibroblast radiosensitivity. The SF2 of skin fibroblasts may potentially be used as a predictive assay to detect patients at risk for brain necrosis.