Toso S, Piccoli A, Gusella M, Menon D, Bononi A, Crepaldi G, Ferrazzi E
Division of Medical Oncology, General Hospital, Rovigo, Italy.
Nutrition. 2000 Feb;16(2):120-4. doi: 10.1016/s0899-9007(99)00230-0.
Modifications of body composition are frequent in cancer patients. Bioelectric impedance analysis can specifically detect changes in tissue electric properties, which may be associated with outcome. We evaluated the distribution 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 m.o. was the same in both groups (stable/increased 36% and decreased in 62%). Patients were compared with 56 healthy subjects matched for gender, age, and body mass index (25 kg/m2). Impedance measurements (standard tetrapolar electrode placement on the hand and foot) were made with 50-kHz alternating currents. The resistance and reactance of the vector components were standardized by the height of the subjects and were plotted as resistance/reactance graphs. The impedance vector distribution was the same in patients with either stage IIIB or IV cancer. The mean vector position differed significantly between cancer patients and control subjects (Hotelling T2 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 degrees had a significantly shorter, i.e., 18 m.o., survival. Body weight loss was not significantly associated with survival. In conclusion, impedance vectors from lung cancer patients were characterized by a reduced reactance component. The altered tissue electric properties were more predictive than weight loss of prognosis.
癌症患者身体成分的改变很常见。生物电阻抗分析能够特异性地检测组织电特性的变化，而这些变化可能与预后相关。我们评估了63例成年男性肺癌患者（ⅢB期33例，Ⅳ期30例）在支持治疗中的阻抗向量分布情况。两组患者过去6个月的体重变化相同（稳定/增加36%，减少62%）。将患者与56名性别、年龄和体重指数（25kg/m²）相匹配的健康受试者进行比较。采用50kHz交流电进行阻抗测量（在手部和足部放置标准四极电极）。向量分量的电阻和电抗通过受试者身高进行标准化，并绘制为电阻/电抗图。ⅢB期或Ⅳ期癌症患者的阻抗向量分布相同。由于两个癌症组的电阻分量保持不变，但电抗分量降低（即相位角较小），癌症患者与对照受试者的平均向量位置存在显著差异（Hotelling T2检验，P<0.01）。相位角小于4.5度的患者生存期显著缩短，即18个月。体重减轻与生存期无显著相关性。总之，肺癌患者的阻抗向量特征是电抗分量降低。组织电特性的改变比体重减轻对预后更具预测性。
