Colorectal cancer: Less red meat, more fiber

Red and processed meats increase the  risk of developing colorectal cancer.

The new report, just released as part of the World Cancer Research Fund and American Institute for Cancer Research (WCRF/AICR) Continuous Update Project (CUP), examined the links between colorectal cancer risk and diet, physical activity and weight - and update the findings of the 2007 Expert Report.

AICR now recommends people limit consumption to 18 cooked ounces of red meat a week – roughly the equivalent of five or six small portions of beef, lamb or pork – and avoid processed meat.

Experts say ounce for ounce, consuming processed meat increases risk twice as much as consuming red meat.

The American Cancer Society says, excluding skin cancers, colorectal cancer is the third most common cancer diagnosed in both men and women in the United States and third leading cause of cancer-related death in the United States. Recent estimates put the number of new colon cancer cases in the United States are for 2011 at 101,700 with an additional 39,510 new cases of rectal cancer.

The ACS says  the lifetime risk of developing colorectal cancer is about 1 in 20, or 5 percent, and is slightly lower in women. It is expected to cause about 49,380 deaths this year.

The new findings regarding red and processed meat come from 10 new cohort studies added to the 14 previously  included in the 2007 report on colorectal cancer risk.

The new systematic review of the evidence was carried out by WCRF/AICR–funded scientists at Imperial College London, who overall  added 263 new papers on colorectal cancer to the 749 previously in the  2007 report.

The CUP Expert Panel also concluded  foods containing dietary fiber reduce colorectal cancer risk - adding seven more studies to the existing eight from the 2007 Report and reaffirming AICR's recommendation for people to eat a plant–based diet, including whole grains, fruits, vegetables and beans.

Maintaining a healthy weight and being physically active are both linked to lowering colon cancer risk, while a healthy weight is linked to lower rectal cancer risk. Carrying excess fat, especially around the waist, is a convincing cause of colorectal cancer. There is also convincing evidence alcohol consumption increases colorectal cancer risk in men and probably  in women.

"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."