Inadequacy of oleic acids in erythrocytes as a marker for malignancies

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.

Erythrocyte membrane fatty acid composition in hypercholesterolaemia

The fatty acid composition of the erythrocyte membrane was determined in 22 hypercholesterolaemic patients managed by dietary restriction, and compared with that of 22 normocholesterolaemic controls, roughly matched for age and sex with the patient group. The patients exhibited higher relative proportions of palmitic (P < 0.01) and stearic (P < 0.005) acids and lower relative proportions of linoleic acid (P < 0.05) in the erythrocyte membrane, compared with controls, which could be due to presumed dietary differences between the groups. In the patients, the degree of hypercholesterolaemia was poorly correlated with erythrocyte linoleic acid. Measurement of erythrocyte linoleic acid might prove useful in the routine management of hypercholesterolaemia.

Erythrocyte stearic to oleic acid ratio in patients with ocular melanoma

The main characteristics of malignant cells include increased metabolism and capacity for division which are associated with high membrane fluidity. Membrane fluidity is in turn controlled by multiple factors which include the ratio of saturated to unsaturated fatty acids in the cell wall i.e. the Saturation Index (SI). The SI is known to be reduced in neoplastic cells as well as in the circulating erythrocytes of patients with some malignant tumours but not others. It has been suggested that the SI may be useful as a marker of malignancy.

Erythrocyte stearic acid desaturation in patients with colorectal carcinoma

The erythrocyte stearic:oleic acid ratio (saturation index) was investigated as a means of differentiating between control subjects (n = 146) and patients with benign (n = 48) and malignant (n = 117) colorectal disease and patients undergoing postoperative follow-up after curative resection (n = 49). Erythrocyte fatty acid profiles were determined by gas liquid chromatography. Neither age, sex, Dukes' stage, nor degree of differentiation of the tumors had a significant effect on the erythrocyte saturation index. The erythrocyte saturation index was lower in patients with primary and recurrent colorectal cancer compared with control subjects and patients with inflammatory bowel disease or benign colonic polyps (P less than 0.0001). The erythrocyte saturation index was not found to be useful in the postoperative follow-up of these patients. Using both saturation index and age as a means of differentiating between patients with primary colorectal cancer and control subjects gave a sensitivity of 67 percent and a specificity of 81 percent.

Increased levels of vaccenic acid in bronchogenic carcinoma tissue

Employing capillary gas liquid chromatography the levels of palmitic, palmitoleic, stearic, oleic, cis-vaccenic, linoleic, arachidonic and docosahexaenoic acids were measured in lung tissue and lung tumours from 28 patients undergoing surgery for bronchogenic carcinoma. There were significant increases in the majority of fatty acids in tumour tissue compared to normal tissue when the results were expressed in absolute units. However, when the relative changes in fatty acid concentration were studied, the most consistent findings were a significant rise in vaccenic acid and a fall in palmitic acid in tumour tissue compared to normal tissue. This change in the vaccenic:palmitic acid ratio may reflect specific changes in fatty acid metabolism in bronchogenic carcinoma tissue involving a delta-9 desaturase.

Erythrocyte membrane stearic and oleic acid ratios in breast cancer

A case control study has been conducted to determine the value of stearic/oleic acid ratios in the erythrocyte membranes of women at the time of presentation with breast cancer. No difference was found between the stearic/oleic acid ratio of cases and that of controls with benign breast condition or normal volunteers. Furthermore, within clinical stages of breast cancer, no differences were detected. This ratio does not appear to be of value as a marker of malignancy, or of tumour burden.