A novel paradigm in radiotherapy planning techniques comparison for dosimetric and secondary cancer risk assessment...

Radiotherapy for right-sided modified radical mastectomy (MRM) patients carries a risk of secondary malignancies due to radiation exposure to nearby organs-at-risk (OARs). Techniques such as 3D-CRT, IMRT (sliding window), and VMAT differ in their dose distribution to these OARs. This retrospective study analyzed dose-volume histograms from 25 female patients with right-sided MRM to compare the three techniques in terms of dosimetric parameters, radiobiological outcomes, and secondary cancer risks. Mean doses to key OARs-the heart, contralateral lung, ipsilateral lung, and contralateral breast-were evaluated, and NTCP calculations were used to quantify radiation-induced secondary malignancy risks. 3D-CRT delivered lower mean doses to contralateral OARs, reducing secondary cancer risks compared to IMRT and VMAT, but was associated with higher NTCP in the ipsilateral lung. VMAT achieved superior target conformity but increased low-dose exposure to contralateral OARs, raising secondary cancer risks. These findings highlight the importance of individualized treatment planning for right-sided MRM patients. Overall, 3D-CRT appears favorable for minimizing secondary cancer risks in contralateral organs, despite higher ipsilateral lung NTCP. This study provides a framework for integrating dosimetric, radiobiological, and secondary cancer risk assessments in radiotherapy planning, supporting future strategies to optimize both efficacy and safety.