Advising men and women with colorectal cancer (CRC) to eat 4 or fewer servings of red and processed meat a week might be good clinical advice to improve their disease-specific survival, according to a new observational study.
Investigators from the American Cancer Society (ACS) found that survivors with consistently high intakes (median of about 4 servings/week or higher) before and after diagnosis had a 79% higher risk for CRC-specific mortality (relative risk, 1.79) than those with intakes consistently below the median.
The increased risk in the high consumers was statistically significant, according to the authors, led by Marjorie McCullough, ScD, from the epidemiology research program at the ACS.
Their study of CRC survivors and meat consumption was published online July 1 in the Journal of Clinical Oncology.
However, such dietary advice to CRC survivors is "speculative" and needs to be clarified with further cohorts, writes Jeffrey Meyerhardt, MD, in an accompanying editorial. He is from the Dana-Farber Cancer Institute in Boston.
Both the authors and Dr. Meyerhardt agree that there is strong evidence that eating red and processed meat increases the risk of developing CRC.
"Studies of red meat and processed meat have been a rare example of fairly consistent results showing an association between increased intake and risk of developing colorectal cancer," writes Dr. Meyerhardt.
Public health guidelines recommend limiting the consumption of these types of meats for cancer prevention, say Dr. McCullough and colleagues.
However, both the authors and editorialist point out that there is scant evidence on how meat intake influences CRC-related mortality after diagnosis.
The authors undertook their study to address that issue.
Dr. McCullough and colleagues reviewed data from the Cancer Prevention Study II Nutrition Cohort and found 2315 men and women who were diagnosed with colon or rectal cancer between 1992 and 2009.
Of the 966 patients who died during the study period, 413 died from CRC.
The authors looked at meat intake before and after the diagnosis of CRC.
Notably, on multivariable analysis, overall meat intake after diagnosis was not associated with death from CRC.
This is a "curious finding," says Dr. Meyerhardt. But the authors argue that meat consumption has to be looked at both before and after diagnosis. They explain that adverse effects from CRC surgery and adjuvant treatment can influence subsequent diet, and that the cohort database did not include such appetite-related information. In other words, after treatment, some patients won't feel like eating much meat. Thus, the study data from this period of time (after diagnosis) are not strong.
Therefore, the authors focused on "long-term" meat consumption, which could be "a more relevant measure and may be better represented by prediagnostic diet than by postdiagnostic diet."
Over this stretch of time, it looks like eating a lot of meat increased the risk of dying from CRC. "Men and women who consistently ate the most red and processed meat before and after diagnosis had a statistically significant higher risk of death as a result of CRC, compared with those who consistently ate the least red and processed meat," the authors note.
The authors have disclosed no relevant financial relationships.
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Cite this: Red, Processed Meats Tied to Increased Risk for CRC Death - Medscape - Jul 03, 2013.