Dosimetric Comparison of Treatment Techniques: Brachytherapy, Intensity-Modulated Radiation Therapy, and Proton Beam in Partial Breast Irradiation

Abstract

Purpose: To perform a dosimetric comparison of 3 accelerated partial breast irradiation techniques: catheter-based brachytherapy (BT), intensity-modulated radiation therapy (IMRT), and proton beam therapy (PBT). Patients and Methods: Twelve patients with left-sided breast cancer treated with SAVI (Strut-Adjusted Volume Implant) were selected in this study. The original BT plans were compared with optimum plans using IMRT and PBT for 34 Gy (RBE) with 1.1 RBE in 10 fractions using identical parameters for target and organs at risk. Results: Significant reduction in maximum dose to the ipsilateral breast was observed with PBT and IMRT (mean 108.58% [PBT] versus 107.78% [IMRT] versus 2194.43% [BT], P ¼ .001 for both PBT and IMRT compared to BT). The mean dose to the heart was 0%, 1.38%, and 3.85%, for PBT, IMRT, and BT, respectively (P , .001 and P ¼ .026). The chest wall mean dose was 10.07%, 14.65%, and 29.44% for PBT, IMRT, and BT, respectively (P ¼ .001 and .013 compared to BT). The PBT was superior in reducing the mean ipsilateral lung dose (mean 0.04% versus 2.13% versus 5.4%, P ¼ .025 and P , .001). There was no statistically significant difference in the maximum dose to the ipsilateral lung, chest wall, 3-mm skin rind or in the mean ipsilateral breast V 50% among the 3 techniques (P ¼ .168, .405, .067, and .780, respectively). PBT exhibited the greatest mean dose homogeneity index of 4.75 compared to 7.18 for IMRT (P ¼ .001) and 195.82 for BT (P , .001). All techniques resulted in similar dose conformality (P ¼ .143). Conclusion: This study confirms the dosimetric feasibility of PBT and IMRT to lower dose to organs at risk while still maintaining high target dose conformality. Though the results of this comparison are promising, continued clinical research is needed to better define the role of PBT and IMRT in the accelerated partial breast irradiation treatment of early-stage breast cancer.

Proton radiotherapy for treating the most common carcinomas

“…The efficacy of proton radiotherapy is similar to other radiotherapy techniques used in such cases, with 5-year disease-free survival and overall survival rates being respectively 94% and 95% [81]. Dosimetric comparisons of various APBI techniques demonstrate that proton radiotherapy, when compared with IMRT and brachytherapy, significantly reduces the maximum dose delivered to health breast tissue, the mean heart dose, the mean chest wall dose and the mean lung dose [87]. Findings by Girodet-Galland et al show that symptoms of skin reactions are more common in proton radiotherapy compared to photon radiotherapy [82].…”

Future Perspectives of Proton Therapy in Minimizing the Toxicity of Breast Cancer Radiotherapy

“…However, it also had the disadvantage of actual skin toxicity occurring over the years observed. Other scientists showed a dosimetry comparison of results for catheter-based brachytherapy (BT), IMPT, and PBT techniques based on generated plans for 12 left-sided breast cancer patients with a strut-adjusted volume implant (SAVI) [ 31 ]. All techniques achieved a comparably similar dose conformality.…”