Human Nutrition Research Centre, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK.
Lancet Oncol. 2012 Dec;13(12):1242-9. doi: 10.1016/S1470-2045(12)70475-8. Epub 2012 Nov 7.
Observational studies report that higher intake of dietary fibre (a heterogeneous mix including non-starch polysaccharides and resistant starches) is associated with reduced risk of colorectal cancer, but no randomised trials with prevention of colorectal cancer as a primary endpoint have been done. We assessed the effect of resistant starch on the incidence of colorectal cancer.
In the CAPP2 study, individuals with Lynch syndrome were randomly assigned in a two-by-two factorial design to receive 600 mg aspirin or aspirin placebo or 30 g resistant starch or starch placebo, for up to 4 years. Randomisation was done with a block size of 16. Post-intervention, patients entered into double-blind follow-up; participants and investigators were masked to treatment allocation. The primary endpoint for this analysis was development of colorectal cancer in participants randomly assigned to resistant starch or resistant-starch placebo with both intention-to-treat and per-protocol analyses. This study is registered, ISRCTN 59521990.
463 patients were randomly assigned to receive resistant starch and 455 to receive resistant-starch placebo. At a median follow-up 52·7 months (IQR 28·9-78·4), 53 participants developed 61 primary colorectal cancers (27 of 463 participants randomly assigned to resistant starch, 26 of 455 participants assigned to resistant-starch placebo). Intention-to-treat analysis of time to first colorectal cancer showed a hazard ratio (HR) of 1·40 (95% CI 0·78-2·56; p=0·26) and Poisson regression accounting for multiple primary events gave an incidence rate ratio (IRR) of 1·15 (95% CI 0·66-2·00; p=0·61). For those completing 2 years of intervention, per-protocol analysis yielded a HR of 1·09 (0·55-2·19, p=0·80) and an IRR of 0·98 (0·51-1·88, p=0·95). No information on adverse events was gathered during post-intervention follow-up.
Resistant starch had no detectable effect on cancer development in carriers of hereditary colorectal cancer. Dietary supplementation with resistant starch does not emulate the apparently protective effect of diets rich in dietary fibre against colorectal cancer.
European Union, Cancer Research UK, Bayer Corporation, National Starch and Chemical Co, UK Medical Research Council, Newcastle Hospitals Trustees, Cancer Council of Victoria Australia, THRIPP South Africa, The Finnish Cancer Foundation, SIAK Switzerland, and Bayer Pharma.
观察性研究报告称，膳食纤维（包括非淀粉多糖和抗性淀粉在内的异质混合物）摄入量较高与结直肠癌风险降低有关，但尚未开展以预防结直肠癌为主要终点的随机试验。我们评估了抗性淀粉对结直肠癌发病率的影响。
在 CAPP2 研究中，林奇综合征患者以 2×2 析因设计随机分配，接受 600mg 阿司匹林或阿司匹林安慰剂或 30g 抗性淀粉或淀粉安慰剂，最长 4 年。随机分组采用 16 个块的大小。干预后，患者进入双盲随访；参与者和研究人员对治疗分配进行了掩盖。本分析的主要终点是接受抗性淀粉或抗性淀粉安慰剂随机分配的参与者发展为结直肠癌，意向治疗和方案分析均采用该终点。该研究已注册，ISRCTN 59521990。
463 名患者被随机分配接受抗性淀粉，455 名患者接受抗性淀粉安慰剂。中位随访 52.7 个月（IQR 28.9-78.4）时，53 名参与者发生了 61 例原发性结直肠癌（463 名接受抗性淀粉随机分配的参与者中有 27 例，455 名接受抗性淀粉安慰剂随机分配的参与者中有 26 例）。首次结直肠癌时间的意向治疗分析显示，风险比（HR）为 1.40（95%CI 0.78-2.56；p=0.26），考虑到多个主要事件的泊松回归得出的发病率比（IRR）为 1.15（95%CI 0.66-2.00；p=0.61）。对于完成 2 年干预的患者，方案分析得出的 HR 为 1.09（0.55-2.19，p=0.80），IRR 为 0.98（0.51-1.88，p=0.95）。在干预后随访期间没有收集关于不良事件的信息。
抗性淀粉对遗传性结直肠癌携带者的癌症发展没有明显影响。膳食补充抗性淀粉并不能模拟富含膳食纤维的饮食对结直肠癌的明显保护作用。
欧盟、英国癌症研究中心、拜耳公司、国家淀粉和化学公司、英国医学研究理事会、纽卡斯尔医院受托人、澳大利亚维多利亚癌症委员会、THRIPP 南非、芬兰癌症基金会、SIAK 瑞士和拜耳制药。
