González‐Gil, Esther M.

AbstractBased on the World Cancer Research Fund Global Cancer Update Programme, we performed systematic reviews and meta‐analyses to investigate the association of post‐diagnosis adiposity, physical activity, sedentary behaviour, and dietary factors with colorectal cancer prognosis. We searched PubMed and Embase until 28th February, 2022. An independent expert committee and expert panel graded the quality of evidence. A total of 167 unique publications were reviewed, and all but five were observational studies. The quality of the evidence was graded conservatively due to the high risk of several biases. There was evidence of non‐linearity in the associations between body mass index and colorectal cancer prognosis. The associations appeared reverse J‐shaped, and the quality of this evidence was graded as limited (likelihood of causality: limited‐no conclusion). The evidence on recreational physical activity and lower risk of all‐cause mortality (relative risk [RR] highest vs. lowest: 0.69, 95% confidence interval [CI]: 0.62–0.77) and recurrence/disease‐free survival (RR: 0.80, 95% CI: 0.70–0.92) was graded as limited‐suggestive. There was limited‐suggestive evidence for the associations between healthy dietary and/or lifestyle patterns (including diets that comprised plant‐based foods), intake of whole grains and coffee with lower risk of all‐cause mortality, and between unhealthy dietary patterns and intake of sugary drinks with higher risk of all‐cause mortality. The evidence for other exposures on colorectal cancer outcomes was sparse and graded as limited‐no conclusion. Analyses were conducted excluding cancer patients with metastases without substantial changes in the findings. Well‐designed intervention and cohort studies are needed to support the development of lifestyle recommendations for colorectal cancer patients.

Abstract The role of diet in colorectal cancer prognosis is not well understood and specific lifestyle recommendations are lacking. We searched for randomised controlled trials (RCTs) and longitudinal observational studies on post‐diagnosis dietary factors, supplement use and colorectal cancer survival outcomes in PubMed and Embase from inception until 28th February 2022. Random‐effects dose–response meta‐analyses were conducted when at least three studies had sufficient information. The evidence was interpreted and graded by the CUP Global independent Expert Committee on Cancer Survivorship and Expert Panel. Five RCTs and 35 observational studies were included (30,242 cases, over 8700 all‐cause and 2100 colorectal cancer deaths, 3700 progression, recurrence, or disease‐free events). Meta‐analyses, including 3–10 observational studies each, were conducted for: whole grains, nuts/peanuts, red and processed meat, dairy products, sugary drinks, artificially sweetened beverages, coffee, alcohol, dietary glycaemic load/index, insulin load/index, marine omega‐3 polyunsaturated fatty acids, supplemental calcium, circulating 25‐hydroxyvitamin D (25[OH]D) and all‐cause mortality; for alcohol, supplemental calcium, circulating 25(OH)D and colorectal cancer‐specific mortality; and for circulating 25(OH)D and recurrence/disease‐free survival. The overall evidence was graded as ‘limited’. The inverse associations between healthy dietary and/or lifestyle patterns (including diets that comprised plant‐based foods), whole grains, total, caffeinated, or decaffeinated coffee and all‐cause mortality and the positive associations between unhealthy dietary patterns, sugary drinks and all‐cause mortality provided ‘limited—suggestive’ evidence. All other exposure‐outcome associations provided ‘limited—no conclusion’ evidence. Additional, well‐conducted cohort studies and carefully designed RCTs are needed to develop specific lifestyle recommendations for colorectal cancer survivors.