How Genetics Combined with Red Meat Consumption May Raise Colorectal Cancer Risk

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Red meat is a known carcinogen. Now researchers say it raises colorectal cancer risk even higher for people with a genetic predisposition. Andrew Cebulka/Stocksy
  • Previous research suggests that eating large amounts of red or processed meat can increase someone’s risk for colorectal cancer.
  • Researchers are now interested in understanding how someone’s genetics influence their colorectal cancer risk from eating red and processed meat.
  • A recent study identified two biomarkers associated with a higher risk for colorectal cancer from red meat consumption. Participants with these biomarkers had a higher risk for colorectal cancer when they consumed higher amounts of red meat.

Colorectal cancer is one of the more serious cancer subtypes.

It can be challenging to treat at more advanced stages, so researchers are continuing to look for ways to help prevent the disease.

One area of interest is how a person’s genetics influence their chances of developing colorectal cancer and how these genetics influence modifiable risk factors.

A study published in Cancer Epidemiology, Biomarkers & Prevention identified two genetic variants that may increase a person’s chances of developing colorectal cancer when they consume large amounts of red meat.

Researchers say people with these genetic variations may need to exercise extra caution when it comes to red meat consumption.

Colorectal cancer is the second leading cause of cancer death in the United States and researchers note that much of colorectal cancer risk is related to modifiable risk factors.

One significant risk factor is consuming large amounts of red or processed meat, although researchers are still seeking to understand all the reasons why this is a risk factor. Genetics also affect someone’s risk for colorectal cancer.

Researchers in the new study wanted to look at the gene-environment interaction, which involves how genetics and environmental factors interact to affect people’s cancer risk. They said they wanted to understand how particular genetics affected the risk for colorectal cancer from eating red or processed meat. They conducted a genome-wide gene-environment scan.

This analysis included data from a vast number of participants. Overall, researchers included data from 27 studies in their analysis. Researchers excluded participants who had advanced cancer. In all, they studied 29,842 participants with colorectal cancer and 39,625 people without the disease.

Researchers looked at the consumption of red and processed meat among participants and performed genetic analyses. Researchers said they found that participants who were older, obese, and consumed more daily calories had a higher risk for colorectal cancer. They also found that people who consumed higher amounts of red meat, processed meat, or both had a higher risk for colorectal cancer.

Researchers were further able to identify two genetic variants that may change people’s risk for colorectal cancer based on their red meat consumption. However, they did not find genetic variants that increased the risk related to processed meat consumption at a significant level.

Mariana Stern, PhD, a study author and an associate director for population science at the USC Norris Comprehensive Cancer Center in California, explained to Medical News Today:

“Our study pooled data from 27 different studies done across multiple countries. We investigated if the association between red meat intake and colorectal cancer risk differed depending on the genetic makeup of each participant. We found that there are two genetic variants that seem to influence the effect of red meat on colorectal cancer. Whereas everyone is at risk of colorectal cancer when red meat consumption is high, the increase in risk can be higher for people who carry specific genetic variants.”

This research did have certain limitations.

First, it focused on people with European ancestry, meaning future studies should include looking at more diverse genetics.

The data on meat consumption relied on participant reports, which introduces recall bias and misclassification risks. Other information, such as data on lifestyle, also relied on self-reporting.

Researchers further did not consider certain behavioral patterns such as exercise as confounders in their analysis.

Finally, researchers were limited by the limitations of the studies they chose to include in their analysis. For example, in the cohort studies, researchers collected data on risk factors in a specific time frame, which could have influenced results. Four studies did not report on total caloric intake, so these studies could not contribute that information to the final analysis. Dividing meat consumption into quantiles also doesn’t account for everything regarding meat consumption.

Researchers also focused on the most common type of colorectal cancer, so the results may not be as applicable to more rare colorectal cancer types. More research may also be needed to explore the relationship between genetics and processed meat consumption.

Despite these limitations, experts say the results indicate that some people may need to be more cautious about consuming red meat. Stern noted the following:

“High consumption of red meat (more than 18 ounces per week or more than 3 regular servings per week) can increase colorectal cancer for everyone. Our findings suggest some people may have an even higher risk. If our findings are confirmed, these results could be used to identify people in the population who may want to adhere to current recommendations more tightly given their unique genetic predisposition.”

Regardless of non-modifiable risk factors, experts say people can take certain steps to reduce their chances of developing colorectal cancer. Specific lifestyle changes such as quitting smoking and changing diet may help.

Dr. Anton Bilchik, a surgical oncologist as well as the chief of medicine and director of the Gastrointestinal and Hepatobiliary Program at Providence Saint John’s Cancer Institute in California who was not involved in the study, noted that “Most of colorectal cancer is preventable through diet and lifestyle. Risk factors include obesity, smoking, processed food, red meat, and a sedentary lifestyle. Avoiding these risk factors at an early reduces the chances of getting colorectal cancer by as high as 70 percent.”

Doctors can discuss these modifiable risk factors with their patients, according to Dr. Babak Firoozi, a gastroenterologist at MemorialCare Orange Coast Medical Center in California who was not involved in the study.

“Based on previously published data, and further supported by this study, obesity, diabetes, alcohol and tobacco, consumption of red and processed meats, lack of exercise, and low fiber diet all contribute to developing colon cancer,” Firoozi told Medical News Today. These are modifiable risk factors and should be discussed with patients for cancer prevention and overall health.”

As research moves forward, Firozzi said doctors can also provide more precise guidance and more easily identify individuals who are more at risk for colorectal cancer. This can lead to better recommendations for colorectal cancer screening.

Currently, the Centers for Disease Control and Prevention recommends routine screening for colorectal cancer beginning when people are 45 years old. This allows for early detection of colorectal cancer. Some people may also benefit from genetic testing to better understand their risk for colorectal cancer.

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