Baron J A, Sandler R S, Haile R W, Mandel J S, Mott L A, Greenberg E R
Department of Community and Family Medicine, Dartmouth Medical School, and the Norris Cotton Cancer Center, Hanover, NH, USA.
J Natl Cancer Inst. 1998 Jan 7;90(1):57-62. doi: 10.1093/jnci/90.1.57.
Recent evidence suggests that folic acid (and derivatives) could contribute to the protective effect of fruits and vegetables against the risk of large-bowel cancer. Other evidence indicates that alcohol drinking and cigarette smoking may impair the biologic actions of folate. We used data from an adenoma prevention trial to investigate the occurrence of colorectal adenomas (possible precursors of colorectal cancer) in association with folate intake, alcohol consumption, and cigarette smoking.
Patients with at least one recent large-bowel adenoma were followed with colonoscopy 1 year and 4 years after their qualifying colon examinations. Adenomas detected after the year 1 examination were used as end points. A food-frequency questionnaire was administered at study entry and at study completion; nutrient intake at study entry was used in this analysis. All statistical tests were two-sided.
After adjustment for caloric intake, dietary folate had a significant protective association with the risk of recurrence of large-bowel adenoma (P for trend = .04). However, this inverse association was attenuated by further adjustment for intake of dietary fiber and fat. Use of folate supplements was not associated with a reduction in risk. Alcohol intake (seven or more drinks/week) was associated with increased risk (odds ratio = 2.04; 95% confidence interval = 1.28-3.26). Cigarette smoking, even smoking for long duration, was not related to adenoma recurrence.
These data provide only modest support for previous findings suggesting beneficial effects of folate on colorectal adenoma risk. We find no evidence that cigarette smoking increases risk. These findings do suggest a substantial increase in risk with alcohol consumption.
最近的证据表明，叶酸（及其衍生物）可能有助于水果和蔬菜对预防大肠癌风险的保护作用。其他证据表明，饮酒和吸烟可能会损害叶酸的生物学作用。我们利用一项腺瘤预防试验的数据，研究结直肠腺瘤（结直肠癌的可能前期病变）的发生与叶酸摄入量、饮酒量和吸烟之间的关系。
对至少有一个近期大肠腺瘤的患者，在其合格的结肠镜检查后1年和4年进行结肠镜随访。将1年检查后发现的腺瘤用作终点。在研究开始时和结束时发放食物频率问卷；本分析采用研究开始时的营养素摄入量。所有统计检验均为双侧检验。
在调整热量摄入后，膳食叶酸与大肠腺瘤复发风险有显著的保护关联（趋势P值 = 0.04）。然而，在进一步调整膳食纤维和脂肪摄入量后，这种反向关联减弱。使用叶酸补充剂与风险降低无关。饮酒量（每周七杯或更多）与风险增加有关（比值比 = 2.04；95%置信区间 = 1.28 - 3.26）。吸烟，即使是长期吸烟，与腺瘤复发无关。
这些数据仅为先前关于叶酸对结直肠腺瘤风险有益作用的研究结果提供了适度支持。我们没有发现吸烟会增加风险的证据。这些发现确实表明饮酒会使风险大幅增加。
