Antioxidant supplement and long-term reduction of recurrent adenomas of the large bowel. A double-blind randomized trial.

BACKGROUND: Patients who undergo polypectomy are at increased risk of adenoma recurrence. The preventive potential of vitamins (A, C and E) and selenium supplementation represent an interesting opportunity for colorectal cancer prevention. METHODS: To assess the efficacy of a combination of these micronutrients in reducing the incidence of recurrent adenomas in subjects on post-polypectomy endoscopic follow-up, a double-blind placebo-controlled randomized trial was started in Italy in 1988. A total of 411 patients were randomized to receive either an active compound (200 µg selenium, 30 mg zinc, 2 mg vitamin A, 180 mg vitamin C, 30 mg vitamin E) or a placebo daily for 5 years. Of them, 330 had follow-up colonoscopy (164 in the intervention and 166 in the placebo group). RESULTS: After a median follow-up of 4 years (range 1-15 years), 100 patients had recurrence: 38 in the intervention and 62 in the placebo arm. The 15-year cumulative incidence of recurrence was 48.3% in the intervention and 64.5% in the placebo arm (HR = 0.59; log-rank P = 0.009). A 39% reduction of the risk of recurrence was observed in the intervention compared to the placebo group (adjusted HR = 0.61; 95% CI 0.41-0.92): the risk reduction was similar for small tubular (adjusted HR = 0.61; 95% CI 0.37-0.99) and advanced adenomas (adjusted HR = 0.50; 95% CI 0.24-1.01). CONCLUSIONS: Our study showed a statistically significant effect of antioxidant supplementation on adenoma recurrence. Further clinical trials are needed to address the role of antioxidants in subgroups of subjects at increased risk for colorectal cancer.

A randomized, placebo-controlled, preoperative trial of allopurinol in subjects with colorectal adenoma.

Inflammation and oxidative stress play a crucial role in the development of colorectal cancer (CRC) and interference with these mechanisms represents a strategy in CRC chemoprevention. Allopurinol, a safe molecular scavenger largely used as antigout agent, has been shown to increase survival of patients with advanced CRC and to reduce CRC incidence in long-term gout users in epidemiologic studies. We conducted a randomized, double-blind, placebo-controlled preoperative trial in subjects with colorectal adenomatous polyps to assess the activity of allopurinol on biomarkers of colorectal carcinogenesis. After complete colonoscopy and biopsy of the index polyp, 73 subjects with colorectal adenomas were assigned to either placebo or one of two doses of allopurinol (100 mg or 300 mg) and treated for four weeks before polyp removal. Change of Ki-67 labeling index in adenomatous tissue was the primary endpoint. Secondary endpoints were the immunohistochemical (IHC) expression of NF-κB, ß-catenin, topoisomerase-II-α, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) in adenomatous polyps and normal adjacent colonic tissue. Compared with placebo, Ki-67 levels were not significantly modulated by allopurinol, whereas ß-catenin and NF-κB expression levels decreased significantly in adenomatous tissue, with a mean change from baseline of -10.6%, 95% confidence interval (CI), -20.5 to -0.7, and -8.1%, 95% CI, -22.7 to 6.5, respectively. NF-κB also decreased significantly in normal adjacent tissue (-16.4%; 95% CI, -29.0 to -3.8). No dose-response relationship was noted, except for NF-κB expression in normal tissue. Allopurinol can inhibit biomarkers of oxidative activation in colon adenomatous polyps and normal adjacent tissue. Further studies should define its potential chemopreventive activity.

Long-term endoscopic surveillance of patients with Barrett's esophagus. Incidence of dysplasia and adenocarcinoma: a prospective study.

OBJECTIVE: Barrett's esophagus (BE) is a premalignant condition for which regular endoscopic follow-up is usually advised. We evaluated the incidence of esophageal adenocarcinoma (AC) in patients with BE and the impact of endoscopic surveillance on mortality from AC. METHODS: A cohort of newly diagnosed BE patients was studied prospectively. Endoscopic and histological surveillance was recommended every 2 yr. Follow-up status was determined from hospital and registry office records and telephone calls to the patients. RESULTS: From 1987 to 1997, BE was diagnosed in 177 patients. We excluded three with high-grade dysplasia (HGD) at the time of enrollment. Follow-up was complete in 166 patients (135 male, 31 female). The mean length of endoscopic follow-up was 5.5 yr (range 0.5-13.3). Low-grade dysplasia (LGD) was present initially in 16 patients (9.6%) and found during follow-up in another 24 patients. However, in 75% of cases, LGD was not confirmed on later biopsies. HGD was found during surveillance in three patients (1.8%), one with simultaneous AC; two with HGD developed AC later. AC was detected in five male patients during surveillance. The incidence of AC was 1/220 (5/1100) patient-years of total follow-up, or 1/183.6 (5/918) patient-years in subjects undergoing endoscopy. Four AC patients died, and one was alive with advanced-stage tumor. The mean number of endoscopies performed for surveillance, rather than for symptoms, was 2.4 (range 1-10) per patient. During the follow-up years the cohort had a total of 528 examinations and more than 4000 biopsies. CONCLUSIONS: The incidence of AC in BE is low, confirming recent data from the literature reporting an overestimation of cancer risk in these patients. In our patient cohort, surveillance involved a large expenditure of effort but did not prevent any cancer deaths. The benefit of surveillance remains uncertain.