Spectral characteristics of electrogastrography in gastric cancer. Possibilities of screening

A standardised application of electrogastrography (EGG) using spectral analysis was used in 182 subjects (72 normals, 74 cancerous and 36 ulcerous) in a large range of the aging (10 to 70 years). The conditions of derivations from the abdominal surface electrodes (n = 6) are following: bipolar distance 14 cm around the pyloric point at 0 degrees (antrum axis), 60 degrees and 120 degrees. In fasting situation in normal subjects the gastric frequency (N) and the spectral amplitude (Y) of the most energetic component of EGG was 2.89 +/- 0.2 c/min for N and 54 +/- 44 microV for Y in antropyloric axis. In the cancerous group a significative increase of mean amplitude is observed (P = 0.01). On the contrary any mean change of frequency was observed (2.89 +/- 0.3 c/min). The individual comparison with normal parameters leads to following selection: neoplasia, n = 42/74 cases (57%); ulcer, n = 13/36 (36%); however 7/72 normal subjects (10%) fall in this abnormal class as false positive. After an ingestion of tea (120 ml) giving a volumetric stimulation, the modifications of frequency are not significative contrary to the amplitude increase. Finally, the association of one or two abnormalities leads to the following percentages: 66% in cancerous, 45% in ulcerous and 23% in normal subjects. Thus a better proportion of abnormalities was observed in cancerous subjects with the stimulation but this procedure may lead to an increase of false abnormality in the non-neoplastic subjects.