Risk of Radiation Induced Carotid Artery Stenosis in Supraclavicular Lymph Node Irradiation in Breast Cancer Patients

Abstract

Background: The risk of carotid vessel stenosis is high after radiotherapy (RT) to neck; however, carotid vessels are unavoidable during supraclavicular (SC-RT) in adjuvant treatment of breast cancer (BC). However, carotid vessels RT dose is less well-understood. We aimed to determine the carotid vessels doses received by different techniques for SC-RT. Materials and Methods: Thirty consecutive BC patients were planned to receive SC-RT and breast after breast conserving surgery (BCS) after taking 5 mm image slices on computed tomography (CT) simulation. Organs at risk (OAR) including carotid vessels, lungs, spinal cord alongwith clinical target volume (CTV) for primary tumor and lymph nodes were delineated. Comparative analysis was done between two treatment plans; three-field conformal radiation therapy (3F-CRT) and four field conformal RT (4F-CRT) for CTV and carotid vessels doses. Results: The 4F-CRT was found better than 3F-3DCRT regarding coverage and homogeneity of the CTV volume. The 98% of the CTV was covered by 84% dose in 3F-CRT and 95% in 4F-CRT (p 0.001). The carotid vessels maximum dose in the in 3F-CRT was 54.5 ± 1.3 Gy compared to 51.6 ± 1.3 Gy in 4F-CRT (p 0.014), however the mean dose did not differ significantly (p value 0.8). The ipsilateral lung dose did not differ between the two techniques (p Value 0.9). Conclusion: The 4F-CRT plan was found better than 3F-CRT in CTV coverage with minimal dose to the carotid vessel and without significant higher dose to the ipsilateral lung.