Dosimetric and Secondary Cancer Risk Comparison after Radiation Therapy for Breast Cancer with Three-Dimensional...

This study aimed to compare the dose distribution and excess absolute risk (EAR) of secondary cancer risk for women with left breast cancer treated with mastectomy who were candidates for adjuvant radiotherapy between three-dimensional conformal radiotherapy (3D-CRT) and helical therapy (HT) techniques.

For each patient planed with 3D-CRT, a plan was created for HT treatment, and data concluding maximum dose (Dmax), mean dose (Dmean), V5, V10, V20, and V30 were extracted from treatment planning systems. Organ equivalent dose (OED) and EAR were calculated based on the extracted data from dose-volume histogram (DVH).

In terms of Dmax, HT technique showed lower values for the heart, spinal cord, and ipsilateral lung compared to 3D-CRT technique. For the thyroid, esophagus, contralateral breast and lung, 3D-CRT technique yielded lower Dmax values. For Dmean, HT technique showed lower values only for the ipsilateral lung, while 3D-CRT technique produced lower values for the remaining organs. For V5, V10, V20, and V30, 3D-CRT technique generally exhibited lower values compared to HT technique, except the ipsilateral lung, where HT technique displayed lower values for V10, V20, and V30. For the heart, HT technique showed lower values for V20 and V30. As a result, HT technique resulted in higher OEDs and EARs for the contralateral breast and lung, while 3D-CRT technique produced higher OEDs and EARs for the ipsilateral lung.

HT and 3D-CRT exhibit varying efficacies in treating breast cancer patients, with HT demonstrating superior outcomes for sparing the heart and ipsilateral lung, while 3D-CRT holds an edge in minimizing dose to the contralateral breast and lung. The choice of the most appropriate radiation therapy technique for a particular patient should be made on a case-by-case basis, respecting the risk of secondary cancer development, pneumonitis, radiation-induced cardiac events, age, overall health.