WHO’S CANCER AGENCY LINKED BACON AND HOT DOGS TO CANCER

The World Health Organization’s cancer agency ruled on October 26, 2015 that processed meat such as bacon, ham and hot dogs is carcinogenic to humans, because there was sufficient evidence that eating it causes colorectal cancer. The same panel of experts put red meat one rung lower, calling it “probably carcinogenic to humans.”

The International Agency for Research on Cancer (IARC) made the call from Lyon, France. A working group of 22 experts from 10 countries reviewed the accumulated scientific literature before sorting processed meat into Group 1 and red meat into Group 2A.

The red-meat label rested on limited evidence in humans, paired with strong mechanistic evidence supporting a carcinogenic effect. That link was seen mainly for colorectal cancer, with associations also observed for pancreatic and prostate cancers.

The summary was published online in The Lancet Oncology the same day. The detailed assessments were published as IARC Monographs Volume 114, which covered more than 800 epidemiological studies of cancer at more than 15 sites.

A label about evidence, not size

The headline number came from IARC’s own announcement. Each 50-gram portion of processed meat eaten daily was associated with an 18% increase in colorectal-cancer risk. According to IARC’s Q&A, that estimate came from an analysis of data from 10 studies, and risk generally rose with the amount of processed meat eaten.

IARC defined processed meat as meat transformed through salting, curing, fermentation, smoking or other processes to improve flavor or preservation. Its examples included hot dogs, ham, sausages, corned beef, beef jerky and canned meat. Red meat meant unprocessed mammalian muscle meat, such as beef, veal, pork and lamb.

The Q&A said the evidence linking processed meat to stomach cancer was not conclusive. It also said the available data did not allow a conclusion about whether a safe level of processed-meat consumption exists.

The catch is that IARC’s categories describe how strong the evidence is that something can cause cancer. They do not measure how big the risk is.

The American Institute for Cancer Research (AICR) said it “strongly supports” the report and hoped it would spread awareness that diet plays a role in cancer risk. It also pointed to CDC information that cigarette smoking can multiply a person’s cancer risk by as much as 20 times, and stressed that the processed-meat classification does not mean the two pose equal levels of risk.

“For years AICR has been recommending that individuals reduce the amount of beef, pork, lamb and other red meats in their diets and avoid processed meats like bacon, sausage and hot dogs,” said Susan Higginbotham, RD, PhD, AICR’s vice-president of research.

“This advice grows out of our expert reports and the Continuous Update Project, our ongoing review and analysis of the global scientific research on how diet, physical activity, and weight affect cancer risk,” she said.

AICR said its own analyses found that regular consumption of even small amounts of processed meat was associated with increased colorectal-cancer risk. It added that some studies found people eating diets high in processed meat had nearly double the colorectal-cancer risk of non-meat-eaters. Moderate red-meat consumption was different, the group said, with no notable increase in colorectal-cancer risk at that level.

AICR recommended avoiding processed meat and eating no more than 18 ounces of cooked red meat a week.

IARC’s Q&A said the evaluation reinforced a 2002 WHO recommendation that people who eat meat moderate their processed-meat consumption to reduce colorectal-cancer risk. Three days after the announcement, on October 29, 2015, WHO issued a clarification saying that earlier advice still stood, according to Hong Kong’s Centre for Food Safety.

AICR’s current recommendation page still tells people who eat red meat to limit it.