Long-term effect of resistant starch on cancer risk in carriers of hereditary colorectal cancer: An analysis from the CAPP2 randomised controlled trial

Human Nutrition Research Centre, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK. Electronic address: .
The Lancet Oncology (Impact Factor: 24.69). 12/2012; DOI: 10.1016/S1470-2045(12)70475-8


Background Observational studies report that higher intake of dietary fi bre (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 eff ect of resistant starch on the incidence of colorectal cancer. Methods 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. Findings 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 fi rst 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. Interpretation Resistant starch had no detectable eff ect on cancer development in carriers of hereditary colorectal cancer. Dietary supplementation with resistant starch does not emulate the apparently protective eff ect of diets rich in dietary fi bre against colorectal cancer.

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