McKeown-Eyssen G, Holloway C, Jazmaji V, Bright-See E, Dion P, Bruce W R
Department of Preventive Medicine and Biostatistics, Faculty of Medicine, University of Toronto, Ontario, Canada.
Cancer Res. 1988 Aug 15;48(16):4701-5.
Because supplements of vitamins C and E had been associated with reduction of fecal mutagen levels, a double-blind randomized trial was designed to examine the effects of these vitamins on the rate of recurrence of colorectal polyps, presumed precursors for colorectal cancer. Two hundred patients believed to be free of polyps after removal of at least one colorectal polyp were randomized to receive a supplement of 400 mg each of ascorbic acid and alpha-tocopherol, or a placebo. Fifteen patients had to be excluded because a review of pathology indicated that their polyps were not adenomatous. A second colonoscopic examination was planned after 2 yr of supplementation. One hundred thirty-seven people (75% of eligible subjects) completed the study; polyps were observed in the second colonoscopy in 41.4% of 70 subjects on vitamin supplements and in 50.7% of 67 subjects on placebos. After adjustment for differences between groups in demographic and dietary factors before study entry, the relative risk of polyp occurrence was 0.86, with 95% confidence limits from 0.51 to 1.45, in an analysis of 129 subjects with complete information on demographic and dietary factors who had completed the trial. Of the 48 patients who had not completed the study, 7 had died, 33 had not returned to their physician for an examination, and 8 had had a follow-up colonoscopy or sigmoidoscopy. Inclusion of the three polyps found in these eight examinations led to an estimate of relative risk of 0.86 (95% confidence limits, 0.51 to 1.43). The findings of this investigation suggest that any reduction in the rate of polyp recurrence associated with vitamin supplementation is small, and a larger study would be required to ensure that an effect of this size was not a chance finding.
由于维生素C和E补充剂与粪便诱变水平降低有关，因此设计了一项双盲随机试验，以研究这些维生素对结直肠息肉复发率的影响，结直肠息肉被认为是结直肠癌的前期病变。200名在切除至少一个结直肠息肉后被认为无息肉的患者被随机分为两组，一组接受每剂400毫克抗坏血酸和α-生育酚的补充剂，另一组接受安慰剂。15名患者因病理检查显示其息肉不是腺瘤性而被排除。计划在补充2年后进行第二次结肠镜检查。137人（75%的符合条件受试者）完成了研究；在接受维生素补充剂的70名受试者中，41.4%在第二次结肠镜检查中发现有息肉，而在接受安慰剂的67名受试者中这一比例为50.7%。在对129名完成试验且有完整人口统计学和饮食因素信息的受试者进行分析时，在对研究入组前两组在人口统计学和饮食因素方面的差异进行调整后，息肉发生的相对风险为0.86，95%置信区间为0.51至1.45。在未完成研究的48名患者中，7人死亡，33人未返回医生处进行检查，8人接受了随访结肠镜检查或乙状结肠镜检查。将这八次检查中发现的三个息肉纳入分析后，相对风险估计为0.86（95%置信区间，0.51至1.43）。这项调查结果表明，与维生素补充相关的息肉复发率降低幅度很小，需要进行更大规模的研究以确保这种规模的效应不是偶然发现。
