Radiobiological comparison of 3D conformal and intensity modulated radiation therapy in the treatment of left-sided breast cancer

Background: The current study aimed to compare the tumor control probability (TCP) and normal tssue complicaton probability (NTCP) of three-dimensional conformal radiaton therapy (3D-CRT) and intensity-modulated radiaton therapy (IMRT) for left-sided breast cancer using radiobiological models. Methods: This study was conducted on 30 patents with left-sided breast cancer, who were planned for 3D-CRT and 6-9 fields IMRT treatments using the PROWESS treatment planning system. The planning target volume (PTV) dose of 50 Gy was administered for the 3D-CRT and IMRT plans, respectvely. The Niemierko's equivalent uniform dose (EUD) model was utlized for the estmaton of tumor control probability (TCP) and normal tssue complicaton probability (NTCP). Results: According to the results, the mean TCP values for 3D-CRT, 6-fields IMRT, and 9-fields IMRT plans were 99.07 ±0.07, 99.24 ±0.05 and 99.28 ±0.04, respectvely, showing no statstcally significant difference. The NTCPs of the lung and heart were considerably lower in the IMRT plans, compared to those in the 3D-CRT plans. Conclusions: From the radiobiological point of view, our results indicated that 3D-CRT produces a lower NTCP for ipsilateral lung. In contrast, for TCP calculatons, there was a higher gain with IMRT plans compared to 3D-CRT plans. © 2020 Novin Medical Radiation Institute. All rights reserved