IARC Classifies Red Meat as a Probably Carcinogenic to Humans and Processed Meat as Carcinogenic to Humans
An International Agency for Research on Cancer’s (IARC) Working Group of 22 experts met October 6-13, 2015, in Lyon, France, to discuss the potential carcinogenicity of red meat (e.g., beef, veal, lamb) and processed meat (e.g., hot dogs, ham, sausage)..
Based on its evaluation, the Working Group classified the consumption of red meat as probably carcinogenic to humans (Group 2A) based on limited evidence in humans and strong mechanistic evidence to support a carcinogenic effect. The Working Group reported the main effect was for colorectal cancer but associations were also seen for pancreatic and prostate cancers. IARC stated limited evidence indicates that “a positive association has been observed between exposure to the agent and cancer but that other explanations for the observations (technically termed chance, bias, or confounding) could not be ruled out.”
Processed meat was classified as being carcinogenic to humans (Group 1) based on sufficient evidence in humans that consumption of processed meat causes colorectal cancer. IARC stated experts concluded the risk of colorectal cancer increases by 18% for each 50 grams (or 1.8 ounces) of processed meat consumed daily. An association with stomach cancer was reported for processed meat, but the evidence was not determined to be conclusive.
Regarding the question of what might be responsible for the reported increase in cancer, IARC states, “…it is not yet fully understood how cancer risk is increased by red meat or processed meat.” The Working Group also stated that while high temperature cooking methods create compounds that may contribute to risk, “…their role is not yet fully understood,” and “there were not enough data for the IARC Working Group to reach a conclusion about whether the way meat is cooked affects the risk of cancer.” IARC reported that there is inadequate evidence in experimental animals for carcinogenicity for both red meat and processed meat.
IARC will publish the results of the meeting and its findings in Volume 114, Consumption of Red Meat and Processed Meat. A copy of the article on summary of the findings of the meeting published in the October 26, 2015, issue of Lancet Oncology can be found here.
The IARC press release on its findings for red meat and processed meat can be downloaded here
A copy of the IARC Q&A on the carcinogenicity of red meat and processed meat can be downloaded here