The identification of post-lumpectomy seromas by radiation therapists in the management of early stage breast cancer

Introduction: In radiation therapy for early stage breast cancer, computed tomography (CT) is used to identify the post-lumpectomy breast seroma. Contouring seromas is a task performed by a radiation oncologist (RO). With increasing demands on the ROs’ time, there is scope for radiation therapists (RTs) to expand their role. This research project aims to compare the ability of RTs with ROs in contouring breast seromas. Methodology: Patient and tumour characteristics along with CT-simulation data sets of patients treated with radiation therapy in 2013 at the Calvary Mater Newcastle were assessed. Study 1, a feasibility study, involved one RT assessing 108 CT data sets (from a sample of 100 patients) for the presence or absence of a post-lumpectomy breast seromas using a novel 4-point seroma visibility rating scale. Study 2 involved 4 RTs, each 50 CT data sets. If a breast seroma was present, a seroma volume was contoured. RT contours were compared to those contoured by a RO. Results: Study 1 reported that out of 108 CT data sets, 1 RT was able to identify the presence of a seroma in 102 cases, versus 104 as contoured by ROs. There were 106 observed agreements (98.15% of the observations); the number of agreements expected by chance were 98.4 (91.15% of the observations. The Kappa statistics equaled 0.791 (SE of kappa = 0.143). The strength of agreement was ‘substantial’. In Study 2, the seroma volumes of the 4 RTs and the ROs were assessed with an Inter Class Correlation coefficient, excellent reliability was reported. A DICE similarity coefficient aided in comparing the overlap, results were favourable. A comparison of the geographical centres of the seroma volumes demonstrated good to excellent reliability. Conclusion: Favorable results from this research has provided further evidence to support RTs in assuming additional contouring responsibilities in radiation therapy planning for patients with early staged breast cancer.