Background: This case-control retrospective study examined whether the extracellular water ratio (%ECW) of the upper extremity, as measured through bioelectrical impedance analysis (BIA), could be an indicator of the development and severity of breast cancer-related lymphedema (BCRL). Methods and Results: BIA was used to evaluate the changes in %ECW due to BCRL development, with the %ECW measured in female patients with unilateral BCRL and healthy controls. Receiver operating characteristic (ROC) analysis was performed to assess the diagnostic ability of %ECW to distinguish BCRL patients from controls. Twenty female patients, who were eligible for inclusion, and 20 healthy control volunteers were included. The %ECW of the affected arm correlated with the water volume difference between the affected and unaffected arms (R2 = 0.7183). ROC analysis showed that %ECW had a high diagnostic ability as a screening tool for BCRL development (area under the ROC curve = 0.982). A cutoff %ECW value of 38.5% could predict the presence of BCRL with a sensitivity of 91.7% and specificity of 97.9%. Conclusions: This study confirmed that %ECW could assess the presence and severity of BCRL in a single measurement noninvasively in a shorter amount of time. The %ECW value strongly correlated with excess arm body water volume, an indicator of the severity of unilateral arm lymphedema. The cutoff %ECW value could predict the presence of BCRL with high accuracy.
Keywords: arm lymphedema; bioelectrical impedance analysis; breast cancer-related lymphedema; extracellular water ratio; lymphedema development; screening test.