Consuming red meat may be linked to colorectal cancer: Study

Over the past few years, experts have recommended eating less meat to prevent colon cancer, but the way it causes cells to mutate hasn’t been clear and some weren’t sure if there was a link.

A new article in the journal Cancer Discovery has now identified specific patterns of DNA damage caused by a diet high in red meat – which further implies the food is carcinogenic while also heralding the possibility of early cancer detection and new treatments develop.

Previous research showing the link was mainly epidemiological, meaning that people who developed the disease were asked about their eating habits and researchers discovered associations with the incidence of colon cancer.

But a lack of clarity on biology meant the case wasn’t a slam dunk, and in 2019 a team of researchers made waves when it stated that it had only a “low” certainty that reducing consumption would prevent cancer deaths.

“If we say red meat is carcinogenic and has an impact on cancer incidence, there has to be a plausible route,” Marios Giannakis, oncologist at the Dana-Farber Cancer Institute who led the new study, told Agence France. Press (AFP).

After all, scientists discovered long ago which chemicals in cigarette smoke are responsible for cancer and how certain bands of UV light penetrate the skin and trigger mutations in genes that control the growth and division of cells.

To fill the knowledge gap, Giannakis and colleagues sequenced DNA data from 900 colon cancer patients from a much larger group of 280,000 health workers who participated in a year-long study of lifestyle surveys.

Detective work

The strength of this approach is that the people documenting their diet had no way of knowing their future cancer diagnosis instead of asking people to remember their eating habits after their illness.

The analysis revealed a unique mutation signature – a pattern that has never been identified before but indicates a type of DNA damage called “alkylation”.

Not all cells containing these mutations will necessarily become cancerous, and the signature was also present in some healthy colon samples.

The mutation signature was significantly associated with ingestion of red meat, both processed and unprocessed, prior to the patient’s diagnosis of cancer, but not with ingestion of poultry, fish, or other lifestyle factors studied.

“There are chemicals in red meat that can cause alkylation,” said Giannakis.

The specific compounds are nitroso compounds, which can be made from heme, which is abundant in red meat, as well as from nitrates, which are commonly found in processed meat.

The mutation patterns were strongly linked to the distal colon – the lower part of the intestine that leads to the anal canal, where previous research suggested that red meat-related colon cancer is the predominant occurrence.

Additionally, among the genes most affected by the alkylation patterns were those that previous research showed were among the most common causes of colon cancer when they mutate.

Taken together, the many lines of evidence make a compelling argument, said Giannakis, comparing the research to careful detective work.

Moderation recommended

In this case, the suspicious mutation signature has a lot to answer for: Patients whose tumors exhibited the highest alkylation damage had a 47% higher risk of colorectal cancer-specific death compared to patients with lower damage.

But Giannakis, also a practicing physician, said it was important to focus on how research can be used to help patients.

Future work could help doctors figure out which patients are genetically predisposed to the accumulation of alkylation damage and then advise them to limit their red meat consumption.

Identifying patients who have already started acquiring the mutation signature could help identify who is at greater risk of developing cancer or getting the disease earlier.

And since the extent of alkylation damage appears to be a biomarker of patient survival, it could potentially be used to inform patients of their prognosis.

Ultimately, understanding the biological pathway through which colon cancer develops paves the way for drugs that interrupt or reverse the process and prevent the disease.

Giannakis insisted the takeaway message was not that people should cut out red meat altogether. “My recommendation would be that moderation and a balanced diet are key.”

High tumor alkylation damage was only observed in patients who averaged more than 150 grams (five ounces) per day, which corresponds to approximately two or more servings.

source https://dailyhealthynews.ca/consuming-red-meat-may-be-linked-to-colorectal-cancer-study/