目前尚无随机、安慰剂对照的临床试验证实有任何干预方式能够作为平均风险个体的结直肠癌初级预防措施。
美国预防服务工作组 (US Preventive Services Task Force, USPSTF) 回顾了存在风险的个体使用阿司匹林预防结直肠癌的证据,并建议符合下列条件的患者使用低剂量阿司匹林作为结直肠癌的初级预防:年龄在 50-59 岁之间、10 年心血管疾病风险≥10%、出血风险没有增加、预期寿命至少为 10 年并且愿意每天服用低剂量阿司匹林至少持续 10 年。[38]Bibbins-Domingo K; US Preventive Services Task Force. Aspirin use for the primary prevention of cardiovascular disease and colorectal cancer: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2016;164:836-845.http://annals.org/aim/article/2513179/aspirin-use-primary-prevention-cardiovascular-disease-colorectal-cancer-u-shttp://www.ncbi.nlm.nih.gov/pubmed/27064677?tool=bestpractice.com USPSTF 还建议对于年龄在 60-69 岁之间、10 年心血管疾病风险≥10% 的成年患者,应基于个体情况考虑是否开始使用低剂量阿司匹林。[38]Bibbins-Domingo K; US Preventive Services Task Force. Aspirin use for the primary prevention of cardiovascular disease and colorectal cancer: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2016;164:836-845.http://annals.org/aim/article/2513179/aspirin-use-primary-prevention-cardiovascular-disease-colorectal-cancer-u-shttp://www.ncbi.nlm.nih.gov/pubmed/27064677?tool=bestpractice.com 由于证据不充分,对于其他年龄组,USPSTF 没有给出建议。
若干随机对照临床试验表明,环氧合酶 (COX-2) 抑制剂可以降低腺瘤复发率,这可能会对之后癌症的发病风险产生影响。[39]Rostom A, Dube C, Lewin G, et al. Nonsteroidal anti-inflammatory drugs and cyclooxygenase-2 inhibitors for primary prevention of colorectal cancer: a systematic review prepared for the U.S. Preventive Services Task Force. Ann Intern Med. 2007;146:376-389.http://www.annals.org/cgi/reprint/146/5/376.pdfhttp://www.ncbi.nlm.nih.gov/pubmed/17339623?tool=bestpractice.com 膳食中补充钙剂 (1200 mg) 也会降低息肉复发率。[40]Baron JA, Beach M, Mandel JS, et al, for The Calcium Polyp Prevention Study Group. Calcium supplements for the prevention of colorectal adenomas. N Engl J Med. 1999;340:101-107.http://www.nejm.org/doi/full/10.1056/NEJM199901143400204#t=articlehttp://www.ncbi.nlm.nih.gov/pubmed/9887161?tool=bestpractice.com 结肠镜切除腺瘤性息肉可预防因结直肠癌所致的死亡。[41]Zauber AG, Winawer SJ, O'Brien MJ, et al. Colonoscopic polypectomy and long-term prevention of colorectal-cancer deaths. N Engl J Med. 2012;366:687-696.http://www.nejm.org/doi/full/10.1056/NEJMoa1100370#t=articlehttp://www.ncbi.nlm.nih.gov/pubmed/22356322?tool=bestpractice.com 根据获益与风险之间的平衡,不支持对平均风险人群进行化学预防。[42]Cook NR, Lee IM, Zhang SM, et al. Alternate-day, low-dose aspirin and cancer risk: long-term observational follow-up of a randomized trial. Ann Intern Med. 2013;159:77-85.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3713531/http://www.ncbi.nlm.nih.gov/pubmed/23856681?tool=bestpractice.com