Eating red meat linked to DNA damage, mutations in patients with colorectal cancer

PHILADELPHIA, Pa. — Red meat and processed foods are typically on the “do not eat” lists of many doctors, mainly because of their link to heart disease and even dementia. Now, a new study finds there’s genetic evidence which may prove eating red meat literally damages your DNA and can lead to colorectal cancer.

Researchers discovered genetic mutations in the distal colon, which is the last part of the organ that includes the descending and sigmoid portions of the colon. These mutations, in both cancerous and cancer-free tissues samples from red meat eaters, all showed signs of alkylation, a specific form of DNA damage.

“We have known for some time that consumption of processed meat and red meat is a risk factor for colorectal cancer,” explains Marios Giannakis, MD, PhD, an assistant professor of medicine at Harvard Medical School and a physician at Dana-Farber Cancer Institute, in a media release.

“What is missing is a demonstration that colorectal cancers from patients have a specific pattern of mutations that can be attributed to red meat,” Giannakis continues. “Identifying these molecular changes in colon cells that can cause cancer would not only support the role of red meat in colorectal cancer development but would also provide novel avenues for cancer prevention and treatment.”

Other meats don’t cause the same damage as red meat

To discover this missing link, researchers sequenced the DNA from normal and colorectal tumor tissue samples from 900 cancer patients. Each patient provided information about their diets and lifestyles for several years leading up to their cancer diagnosis.

Results revealed several markers of genetic mutation in both the normal and cancerous colon tissue, including signs of alkylation. Study authors add they found a strong link between the alkylating signature and patients regularly eating red meat before their diagnosis. Moreover, the team did not find the same connection to DNA damage and eating either chicken or fish before developing colorectal cancer. Researchers note red meat consumption does not appear to have a link to other mutational markers discovered in the study.

When it comes to the colon however, scientists identified alkylation-induced mutation in the KRAS and PIK3CA genes. The team also discovered that colorectal tumors with mutations in these genes had more noticeable signs of alkylation in comparison to tumors without these mutations.

DNA damage can make colorectal cancer even deadlier

Disturbingly, the team finds this alkylating signature in tumors also makes it more likely patients will die from colorectal cancer. Patients with tumors showing high levels of alkylating damage had a 47-percent greater chance of dying from the disease.

“Our study identified for the first time an alkylating mutational signature in colon cells and linked it to red meat consumption and cancer driver mutations,” Giannakis reports. “These findings suggest that red meat consumption may cause alkylating damage that leads to cancer-causing mutations in KRAS and PIK3CA, thereby promoting colorectal cancer development. Our data further support red meat intake as a risk factor for colorectal cancer and also provide opportunities to prevent, detect, and treat this disease.”

Giannakis believes doctors can identify people who have a genetic predisposition for suffering alkylating damage before cancer actually develops. These patients could then receive the proper guidance about lowering their red meat consumption before tumors appear.

The study appears in Cancer Discovery, a journal of the American Association for Cancer Research.