Researchers Find Biological Linkage Between Lean Meat and Colorectal Cancer

Eating less lean meat is standard medical advice for preventing colorectal cancer, but it is unclear how it mutates cells and all experts are convinced that it is strongly associated. Not at all.

A new paper in the journal Cancer Discovery identified specific patterns of DNA damage caused by a lean meat-rich diet. In addition, it suggests food as a carcinogen, telling us the possibility of detecting cancer early and designing new treatments.

Studies prior to establishing relationships were primarily epidemiological. That is, people who developed this condition were investigated for their diet, and researchers found an association with the incidence of colorectal cancer.

However, the lack of biology clarity means that the incident was not a complete slam dunk, and in 2019, one team of researchers said that reducing consumption was “low” to prevent cancer deaths. I made a wave when I declared that I was only convinced.

“When we say that lean meat is carcinogenic and affects the incidence of cancer, we need a plausible way to do it,” said an oncologist at the Dana Farber Cancer Institute, who led the new study. , Marios Jannakis told AFP.

After all, scientists long ago wondered which chemicals in cigarette smoke are responsible for cancer, and how certain bands of UV light penetrate the skin, causing cell growth and division. We have discovered that it causes mutations in the controlling genes.

To address the knowledge gap, Giannakis and his colleagues found 900 people with colorectal cancer extracted from a much larger group of 280,000 healthcare professionals who participated in many years of research, including lifestyle studies. DNA data from patients was sequenced.

Detective work

The strength of this approach is that there was no way for people recording their diet to know their future cancer diagnosis, rather than asking them to remember their diet after getting sick.

The analysis revealed clear signs of mutation. This is a pattern that has never been identified, but it has shown a type of DNA damage called “alkylation.”

Not all cells containing these mutations became cancerous, and some healthy colon samples were also characterized.

Signs of mutation were significantly associated with both processed and raw lean meat intake before the patient was diagnosed with cancer, but poultry, fish, or other lifestyles tested. It was not related to the intake of the factor.

“There are chemicals in lean meat that can cause alkylation,” Giannakis explained.

Certain compounds are nitroso compounds that can be made from heme, which is abundant in lean meats, and nitrates, which are common in processed meats.

Mutation patterns are strongly associated with the distal colon, the lower part of the intestine that connects to the anal canal, and previous studies have suggested that colon cancer associated with lean meat predominantly occurs.

In addition, among the genes most affected by the alkylation pattern, previous studies have shown that they are one of the most common drivers of colorectal cancer when mutated.

Overall, multiple lines of evidence build a compelling argument, Giannakis said, comparing the study to the work of a careful detective.

Promote moderation

In this case, there are many answers to the signs of suspicious mutation. Patients with the highest level of tumor alkylation damage had a 47% higher risk of colorectal cancer-specific mortality compared to patients with lower levels of damage.

But also practitioner Jannakis said it was important to focus on how the study could be used to help patients.

Future studies may help physicians identify which patients have a genetic predisposition to accumulate alkylation damage and advise them to limit lean meat intake.

Identifying patients who are already beginning to show signs of mutation can help identify patients who are at high risk of developing cancer or at an earlier risk of developing the disease.

Also, the amount of alkylation damage appears to be a biomarker of patient survival and could be used to inform patients of prognosis.

Finally, understanding the biological pathways by which colorectal cancer develops paves the way for drugs that disrupt or reverse the process and prevent the disease.

Janakis emphasized that the take-out message does not mean that people should not completely refrain from lean meat. “My recommendation is that a modest and balanced diet is important.”

High levels of tumor alkylation damage were found only in patients who ate an average of 150 grams (5 ounces) or more per day. This is roughly equivalent to two or more servings.