Major Report: Colorectal Cancer Risk Links to Diet, Activity and Weight
The most comprehensive and authoritative report on colorectal cancer risk ever published has concluded that red and processed meat increase risk of the disease and found that the evidence that foods containing fiber offer protection against colorectal cancer has become stronger.
The report, released last week as part of WCRF/AICR's groundbreaking Continuous Update Project, examined the links between colorectal cancer risk and diet, physical activity and weight. The report updated the colorectal cancer findings of AICR/WCRF's 2007 expert report.
"This report shows that colorectal cancer is one of the most preventable cancers," said Elisa Bandera, MD, PhD, who served on the World Cancer Research Fund/ American Institute for Cancer Research's Continuous Update Project (CUP) Expert Panel that authored the report. "AICR has estimated that about 45 percent of colorectal cancer cases could be prevented if we all ate more fiber-rich plant foods and less meat, drank less alcohol, moved more and stayed lean. That's over 64,000 cases in the US every year."
The systematic review of the evidence was carried out by WCRF/AICR-funded scientists at Imperial College London. The scientists added 263 new papers on colorectal cancer to the 749 that were analyzed as part of the 2007 report. An independent CUP Expert Panel then analyzed the totality of evidence and made new judgments.
It's Convincing: Meat Increases and Fiber Decreases Risk
For red and processed meat, the CUP report concluded there is convincing evidence that both red and processed meat increase colorectal cancer risk.
AICR recommends that people limit consumption to 18 ounces (cooked weight) of red meat a week - roughly the equivalent of five or six small portions of beef, lamb or pork - and avoid processed meat. (The report showed that ounce for ounce, consuming processed meat increases risk twice as much as consuming red meat.)
For foods containing dietary fiber, the CUP Expert Panel concluded that the evidence showing it reduced colorectal cancer risk has strengthened since the 2007 report. The evidence was sufficient to strengthen the conclusion that foods containing fiber are protective from "probable" to "convincing."
"AICR has estimated that about 45 percent of colorectal cancer cases could be prevented if we all ate more fiber-rich plant foods and less meat, drank less alcohol, moved more and stayed lean."
Evidence on Activity, Body Weight, Alcohol Still Convincing
The experts concluded that studies published since 2007 added to the evidence that maintaining a healthy weight and being physically active are both convincingly linked to lowering colon cancer risk, while a healthy weight is linked to lower rectal cancer risk. The CUP Expert Panel also found that carrying excess fat - especially around the waist - is a convincing cause of colorectal cancer. There is also convincing evidence that alcohol consumption increases colorectal cancer risk in men and it also probably increases risk in women.
Dr. Alan Jackson, Chair of the WCRF/AICR CUP Expert Panel, said: "Our review has found strong evidence that many cases of colorectal cancer are not inevitable and that people can significantly reduce their risk by making changes to their diet and lifestyle.
"Because our judgments are based on more evidence than ever before, the public can be confident that this represents the best advice available on preventing colorectal cancer.