Acta oncologica
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It is well established that adjuvant radiotherapy (RT) reduces loco-regional recurrences in breast cancer. The effect on overall survival, on the other hand, is a much-debated issue. Some old trials with a long follow-up as well as the first report on the overview of the randomized RT trials initiated before 1975 showed a reduced survival among irradiated patients compared with the surgical controls. ⋯ There are few data concerning the cardiac side effects of RT after conservative surgery. Some studies suggest that radiation-induced heart disease may be a potential problem also among these patients. Therefore, the search for both the causes of radiation-induced heart disease and preventive measures is crucial issues in breast cancer radiation oncology.
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Comparative Study
Comparison between fractionated high dose rate irradiation and continuous low dose rate irradiation in spheroids.
Recent interest in clinical brachytherapy focuses on the possible radiobiological equivalence between fractionated high dose rate (HDR) and continuous low dose rate (LDR) irradiations. This study is designed to compare the radiobiological effects between the two in vitro using multicellular spheroids of human tumor. ⋯ We found that: (1) The fractionated HDR irradiation (8 Gy/2 fr/day) was more effective radiobiologically than continuous LDR irradiation (8 Gy/day) and the ratio of radiobiological effects of these irradiations was estimated as 0.82, based on the 50% spheroid cure dose (SCD50); (2) the radiobiological effectiveness was independent of the fraction size of HDR irradiation administrated, and the repair of sublethal damage (SLD) was absent, suggesting that the sparing effect of fractionated HDR irradiations was absent in spheroids. Our findings could provide important information for the clinical usage of the fractionated HDR radiotherapy to replace continuous LDR radiotherapy.