Radiation Therapy Synchronous Bilateral Breast Cancer—a dosimetric comparison of Volumetric Modulated Arc Therapy (VMAT) and 3D conformal radiation therapy

Background: We aimed to compare the efficiency for various dosimetric parameters and treatment delivery time for volumetric-modulated arc therapy (VMAT) and 3D conformal radiation therapy (3DCRT) treatment plans for bilateral breast cancer (BBC).
Results: The mean volumes of the CTV were (left) 675.1 cc3 ± 220 and (right) 764.0 cc3 ± 197.8. The considered OARs were the lungs, heart, and liver. The VMAT plans provided a better coverage than the 3DCRT ones, the mean values of V95% for breast/chest wall, SCF and axilla were 93.14%, 99.46% and 98.65% with VMAT and 3DCRT, respectively (p = 0.015, 0.016, and 0.015). Similarly, it was also noticed that the VMAT plans achieved lower mean dose to the lungs than the 3DCRT ones, i.e., 12.3 Gy vs. 30.09 for right (p = 0.001), and 12.75 Gy vs. 28.39 for left (p =0.001). The mean treatment time to deliver two arcs was 4.2 minutes (range, 4.1 to 4.3 minutes) compared to 9.0 minutes (range, 8.7 to 13.2 minutes) for 3DCRT
Conclusions: Comparison between VMAT and 3DCRT showed that the VMAT plans were superior in all dose characteristics. However, further studies are warranted to compare VMAT with IMRT for the complex treatment volumes in BBC patients.