Elevated reversible and irreversible lipid peroxidation in human oesophageal cancer.

BACKGROUND

Cancer of the oesophagus is the most common gastrointestinal malignancy in South African blacks. The aim of this study was to determine the reversible and irreversible lipid peroxidation in cancer of the oesophagus; a feature that has not been assessed before in this or other cancer tissue.

METHODS

Biopsies and plasma from 39 patients with cancer of the oesophagus and 22 biopsies and plasma from non-cancer patients were analysed for the irreversible lipid peroxide product malondialdehyde (MDA) and other reversible lipid peroxide products (LPO) by the thiobarbituric acid-reactive substances (TBARS) method.

RESULTS

The mean (+/- SEM) for MDA in plasma from normal patients was 1.697 (0.149), and for cancer patients 4.23 (0.417) nmol MDA/ml. The tissue MDA for normal patients was 0.807 (0.154), and for cancer patients 2.530 (0.379) nmol MDA/mg protein. The mean (+/- SEM) for LPO in plasma from normal patients was 1.929 (0.281), and for cancer patients 12.607 (1.451) nmol MDA/ml. The tissue LPO for normal patients was 2.957 (0.306), and for cancer patients 16.320 (1.868) nmol MDA/mg protein. All the MDA and LPO values for cancer patients were significantly elevated (p < 10(-4)). In oesophageal cancer 85% of the lipid which was peroxidized, was of the reversible type.

CONCLUSIONS

This elevated reversible LPO levels in plasma and oesophageal tissue of cancer patients support the notion that the oxy-radicals in cancer are not under proper metabolic control. Therefore, human oesophageal cancer does not progress to self regression or destruction but rather to more mutagenic changes probably due to high reversible lipid peroxidations.