Scavengers of oxygen-derived free radicals prolong survival in advanced colonic cancer. A new approach.
The influence of oxygen-derived free radicals on survival in advanced colonic cancer was assessed in a prospective randomized controlled double-blind trial using the radical scavengers dimethyl sulphoxide (DMSO) and allopurinol. Following palliative sigmoid colectomy for carcinoma at Dukes' stage D, 306 patients were randomized to the control group or to electrocoagulation of liver secondaries alone or with allopurinol (50 mg by mouth 4 times a day) or DMSO (500 mg by mouth 4 times a day). In 193 fully evaluable patients who were studied for 5 years, allopurinol and DMSO incurred a significant (p < 0.05) survival advantage over the whole period of study. The similarity in efficacy between allopurinol and DMSO and the fact that the only action they share is scavenging oxyradicals, suggest that these radicals mediate the detrimental effects of malignancy and that removing them incurs a survival advantage for patients with advanced colonic cancer.
On the basis of one randomised trial which did not describe its methodology in sufficient detail to assess risk of bias and quality, excluded 27% of patients after randomisation due to various reasons, and is probably not free from selective outcome reporting bias, there is insufficient evidence to conclude that in patients with colonic cancer liver metastases, electro-coagulation alone brings any significant benefit in terms of survival or recurrence compared with the control. In addition, there is insufficient evidence for the effectiveness of adding allopurinol or dimethyl sulphoxide to electro-coagulation. The probability for selective outcome reporting bias in the trial is high. More randomised trials are needed in order to sufficiently validate electro-coagulation with or without co-interventions.