Different methods for target volume delineation of glandular breast tissue following breast-conserving surgery in breast cancer: A comparative study.

The present study aimed to investigate an optimal and feasible method for delineating the target volume of glandular breast tissue following breast-conserving surgery. A total of 15 patients who underwent radiotherapy following breast-conserving surgery were recruited into the study. Clinical target volume was delineated by the following three methods based on computed tomography (CT): Anatomical landmarks (CTVan), breast palpation (CTVpa) and CT scan images (CTVgl). The target volume, degree of inclusion (DI) and conformal index (CI) defined by these methods were compared. The difference was significant between CTVan and CTVgl, and CTVpa and CTVgl (P<0.0001). The CI between CTVan and CTVpa was 0.644±0.122, significantly higher than that between CTVan and CTVgl (0.264±0.108; P<0.0001) or between CTVpa and CTVgl (0.328±0.115; P<0.0001). The DI of CTVpa in CTVan was 0.890±0.08 and the opposite was 0.709±0.144, while that of DI of CTVgl in CTVan or CTVpa was 0.994±0.005 and 0.989±0.008, respectively. The boundary difference between CTVan and CTVpa was 3.35±7.23, 5.57±13.37, 1.75±11.62 and 11.25±4.07 mm for the medial, lateral, cephalic and caudal boundaries, respectively. A significant difference was observed in the target volume of the breast defined by the three methods. The target volume defined by CTVgl was significantly smaller than that identified by the other two methods. Overall, the combination of palpation marks and anatomical landmarks to define the contouring scope of the breast was indicated to be a relatively rational method for delineating the target volume of the breast.