Altered tissue electric properties in lung cancer patients as detected by bioelectric impedance vector analysis

Modifications of body composition are frequent in cancer patients. Bioelect ric impedance analysis can specifically detect changes in tissue electric p roperties, which may be associated with outcome. We evaluated the distribut ion of the impedance vectors from 63 adult male patients with lung cancer, stages IIIB (33 patients) and IV (30 patients), in supportive therapy. Body weight change over the previous 6 mo was the same in both groups (stable/i ncreased 36% and decreased in 62%). Patients were compared with 56 healthy subjects matched for gender, age, and body mass index (25 kg/m(2)). Impedan ce measurements (standard tetrapolar electrode placement on the hand and fo ot) were made with 50-kHz alternating currents. The resistance and reactanc e of the vector components were standardized by the height of the subjects and were plotted as resistance/reactance graphs. The impedance vector distr ibution was the same in patients with either stage IIIB or IV cancer. The m ean vector position differed significantly between cancer patients and cont rol subjects (Hotelling T-2 test, P < 0.01) because of a reduced reactance component (i.e., a smaller phase angle) with preserved resistance component in both cancer groups. Patients with a phase angle smaller than 4.5 degree s had a significantly shorter, i.e., 18 mo, survival. Body weight loss was not significantly associated with survival. In conclusion, impedance vector s from lung cancer patients were characterized by a reduced reactance compo nent. The altered tissue electric properties were more predictive than weig ht loss of prognosis. Nutrition 2000;16:120-124. (C) Elsevier Science Inc. 2000.