Erythrocyte membrane stearic to oleic acid ratio in carcinoma of the gallbladder: a preliminary study

Aims The role of erythrocyte membrane stearic to oleic acid ratio (saturation index) as a marker of malignancy is still unclear, though an association has been found in colorectal carcinoma, bronchogenic carcinoma, leukaemia, lymphoma and in hepatic malignancies. This study aims to investigate the role of the saturation index in primary carcinoma of the gallbladder. Methods This paper describes the results of the stearic to oleic acid ratio determination in 26 subjects with either cholelithiasis or carcinoma of the gallbladder, also including a group of age- and sex-matched controls, using gas chromatography. This is the first report of the saturation index in carcinoma of the gallbladder. Results A significantly lower saturation index was observed in patients with carcinoma of the gallbladder than with cholelithiasis (t=2.19, P = 0.043, T = 47, P<0.05, Wilcoxon P<0.001, F=2192.23, P<0.001; 95% CI 18.45–30.44) and controls (t=2.5, P=0.024, T=36, P<0.05, F=10904.11, P<0.001, Wilcoxon P<0.001; 95% CI 52.42–63.39). Among the carcinoma patients a further lowering was noted in stage IV disease compared with stage III (T=6, P<0.05). Conclusions These changes are probably due to a marked increase in oleic acid content at the expense of stearic acid. This lowering of the saturation index in carcinoma of the gallbladder is similar to that observed previously in the other malignancies.