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Radiobiological and Dosimetric Comparison of Standard and Hypofractionated Regimens in Left-Sided Breast Cancer Radiotherapy Using Forward Intensity-Modulated Technique: Analysis of Dose-Volume Curves and Normal Tissue Complication Probability
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FARZANEH ALLAVEISI1    , ZEINAB SALEHI2 , M.RASHED MAKHDUM , Arian Azadnia3 |
1- Department of Medical Physics, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran & TOHID HOSPITAL , fallaveisi@gmail.com
2- Department of Medical Physics, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran & TOHID HOSPITAL
3- Department of Medical Physics, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran |
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Abstract: (20 Views) |
Background and Aim: This retrospective study investigates and compares two treatment regimens, namely, standard therapy (50 Gy in 25 fractions) and hypofractionated therapy (42.56 Gy in 16 fractions), in forward intensity modulated radiation therapy (FIMRT) for left breast cancer, focusing on dosimetric and radiobiological parameters using a radiobiological model.
Materials and Methods: A total of 103 patients with left breast cancer, with no involvement of supraclavicular and axillary lymph nodes (N0 stage), were selected. The treatment design was performed with one group consisting of 53 patients receiving the standard fractionation (SF) regimen and another group of 50 patients undergoing the hypofractionated (HF) regimen. Analyzed radiobiological parameters based on the Niemierko model included: equivalent uniform dose (EUD), tumor control probability (TCP), normal tissue complication probability (NTCP), and dosimetric parameters such as homogeneity index (DHI) of the target, mean dose (Dmean), volume of the heart receiving 30 Gy (V30Gy), and volume of the lung receiving 20 Gy (V20Gy).
Results: Statistical analysis using the paired t-test showed no significant differences in DHI and tumor control probability (TCP) between the two treatment regimens. The mean dose (Dmean) to the lung and heart did not differ significantly between the standard fractionation (SF) and hypofractionation (HF) groups (p > 0/05). Similarly, no significant differences were observed in lung V20Gy and heart V30Gy (p > 0/05). According to the Niemierko NTCP model, the risk of cardiac toxicity was negligible. However, lung NTCP was significantly lower in the HF group compared to the SF group (p < 0/05). Furthermore, EUD to the lung was significantly lower in the HF regimen than in the SF regimen (10/5 Gy vs. 16/5 Gy; p = 0/04), whereas the EUD to the heart showed no significant difference between the two groups (p = 0/26).
Conclusion: This study demonstrated no significant differences in dosimetric and radiobiological parameters related to tumor control probability between hypofractionated and conventional radiotherapy regimens for left-sided breast cancer. However, the HF regimen was associated with significantly lower radiation-induced pulmonary toxicity compared to the SF regimen. |
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| Keywords: Breast cancer, dose-volume curve, normal tissue complication probability, tumor control probability, radiotherapy treatment planning, standard radiotherapy, hypofractionated radiotherapy, breast cancer, radiobiological model. |
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Type of Study: Original Research |
Subject:
Medical Physics
Received: 2024/11/25 | Accepted: 2025/05/26
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