Comparing four radiotherapy techniques for treating the chest wall plus levels III-IV draining nodes after breast reconstruction

Objective: To compare the dosimetric outcomes of four radiotherapy (RT) techniques for treating the chest wall plus draining nodes after mastectomy and breast reconstruction. Methods: Three-dimensional conformal radiotherapy, linac-based intensity modulated RT, helical tomotherapy (HT) and direct tomotherapy treatments were planned for 40 breast cancer patients. Dose prescription was 50 Gy. Plans were compared in terms of doses to the planning target volume, organs at risk and the homogeneity index. The non-parametric Friedman test for paired data and the Conover post hoc analysis were used for data analysis. Results: HT provided the highest D90 and D98% and the lowest HI, V107% and D2%. HT was associated with the lowest D2% and V25 Gy to the heart in left-sided treatments but the mean cardiac dose was highest. HT provided the highest V5 Gy and V20 Gy to the ipsilateral lung, but the V30 Gy was lower. The contralateral breast and lung were more exposed with HT. Conclusion: The present dosimetric study together with daily use of CT-MV image guided RT have led us to opt for HT after mastectomy and breast reconstruction and to draw up a suitable protocol for treating the chest wall and levels III and IV draining nodes. Advances in knowledge: HT is a suitable for treating the chest wall and levels III and IV draining nodes.