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Erschienen in:
26.12.2016 | Original Research
Strategies for bilateral breast and comprehensive nodal irradiation in breast cancer—a comparison of IMRT and 3D conformal radiation therapy
Erschienen in: Journal of Radiation Oncology | Ausgabe 1/2017
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Purpose
Comprehensive nodal irradiation improves survival in patients with breast cancer. The usual practice of selective nodal irradiation is increasingly viewed as less than adequate but is still widely used. Bilateral breast cancer is a scenario occasionally seen in high-volume centers. We compare dosimetric outcomes in patients undergoing bilateral breast and comprehensive nodal irradiation using standard three-dimensional conformal radiation therapy (3DCRT) versus intensity-modulated radiation therapy (IMRT).
Materials and methods
Volumes were delineated on 10 patients. The 3DCRT technique involved bilateral tangential breast fields, supraclavicular fossa, and axillary fields and an anterior internal mammary chain field; IMRT technique involved 12 multi-field coplanar inverse planning. The dose prescribed was 50 Gy in 25 fractions. Dose-volume histogram statistics, dose homogeneity, and conformity index were analyzed.
Results
IMRT was superior to 3DCRT in terms of PTV coverage, homogeneity index, conformity index (p < 0.005), and superior in reducing the volume of heart receiving over 40 Gy (p < 0.005). Volume of lung receiving over 20 Gy was also reduced (p < 0.005). However, these improvements came at a cost of higher integral dose to the lungs (p < 0.005).
Conclusion
This is the first study of bilateral breast with total regional nodal irradiation. Radiotherapy for bilateral breast and regional lymph nodes is best achieved using IMRT due to its superior ability to cover the target volumes, while minimizing dose to organs at risk. Further studies will reveal if higher integral lung dose translates into clinically significant chronic toxicity given the excellent long-term survival in these patients.