Boron Neutron Capture Therapy for Breast Cancer during Pregnancy: A Feasibility Study

Introduction: the present study aimed to evaluate the feasibility of boron neutron capture therapy (BNCT) for breast cancer (BC) incidence during pregnancy. Material and Methods: Computational models of pregnant women at 3- and 6- month gestational ages were used with two different simulated tumors in their left breasts. The Monte Carlo simulation of tumor irradiation by thermal and epithermal output beams of in-hospital neutron irradiator was performed in five directions. The optimum treatment plans as a combination of the irradiation directions and output beams were then assessed using an optimization code. Results: Based on the findings of the present study, the total irradiation time of ≤ 10 min was needed to deliver a prescribed dose of RX = 24.4 Gy-Eq to gross tumor volume (GTV) in a BNCT single fraction. The dosimetric properties and volume metrics of the optimized treatment plans were obtained and the dose-volume histogram (DVH)-based metrics, were compared to those from conventional radiotherapy. It has been shown that the dose to both target volume and organs at risk (OARs) were within clinically acceptable dose constraints throughout the course of a single- fraction BNCT. Moreover, the fetal dose (~4.8 mGy-Eq) was well below the threshold for secondary cancer incidence (10 mGy) in the first trimester of pregnancy, while for the second trimester of pregnancy, it was much higher (~35.5 mGy-Eq). Conclusion: Regarding the DVH metrics for GTV, maternal OARs, and the fetus, the studied treatment modality was an appropriate alternative treatment, especially for BC incidence in the first trimester of pregnancy.