Fractionated radiation promotes proliferation and radioresistance in bystander A549 cells but not in bystander HT29 cells.

Aims: Recent studies suggest that direct exposure of cells to fractionated radiotherapy might induce radioresistance. However, the effects of fractionated radiotherapy on the non-irradiated bystander cells remain unclear. We hypothesized that fractionated radiotherapy could enhance radioresistance and proliferation of bystander cells.

Fractionated radiotherapy might induce epithelial-mesenchymal transition and radioresistance in a cellular context manner.

Despite the fact that radiotherapy is a main therapeutic modality in cancer treatment, recent evidence suggests that fractionated radiotherapy (FR) might confer radioresistance through epithelial-mesenchymal transition (EMT). Nevertheless, the effects of FR on EMT phenotype and the potential link between EMT induction and radioresistance development yet to be clarified. The aim of this study was to assess whether FR could promote EMT, and to elucidate if induction of EMT contributes to the acquisition of radioresistance.

Effect of Temporal Pattern of Radiation in Intensity Modulated Radiotherapy on Cell Cycle Progression and Apoptosis of ACHN Renal Cell Carcinoma Cell Line.

Background And Objective: The existence of a hypersensitive radiation response to doses below 1 Gy is well established for many normal and tumor cell lines. The aim of this study was to ascertain the impact of temporal pattern modeling IMRT on survival, cell cycle and apoptosis of human RCC cell line ACHN, so as to provide radiobiological basis for optimizing IMRT plans for this disease.

Materials And Methods: The ACHN renal cell carcinoma cell line was used in this study.

Breast Radiotherapy with Mixed Energy Photons; a Model for Optimal Beam Weighting.

Utilization of high energy photons (>10 MV) with an optimal weight using a mixed energy technique is a practical way to generate a homogenous dose distribution while maintaining adequate target coverage in intact breast radiotherapy. This study represents a model for estimation of this optimal weight for day to day clinical usage. For this purpose, treatment planning computed tomography scans of thirty-three consecutive early stage breast cancer patients following breast conservation surgery were analyzed.