Eating less red meat is standard medical advice for preventing colorectal cancer, but the way it causes cells to mutate has remained unclear, and not all experts were convinced there was a strong link.
A new paper in the journal Cancer Discovery has now identified specific patterns of DNA damage triggered by diets rich in red meat further implicating the food as a carcinogen while heralding the possibility of detecting the cancer early and designing new treatments.
But a lack of clarity around the biology meant that the case wasn’t quite slam dunk, and in 2019, one team of researchers made waves when they declared they only had a “low” degree of certainty that reducing consumption would prevent cancer deaths.
After all, scientists discovered long ago which chemicals in cigarette smoke are to blame for cancer, and how certain bands of UV light penetrate the skin and trigger mutations in genes that control how cells grow and divide.
– Detective work –
The analysis revealed a distinct mutational signature a pattern that had never before been identified but was indicative of a type of DNA damage called “alkylation.”
The mutation signature was significantly associated with intake of red meat, both processed and unprocessed, prior to the patient’s diagnosis of cancer, but not with the intake of poultry, fish or other lifetsyle factors that were examined.
The specific compounds are nitroso compounds that can be made from heme, which is plentiful in red meat, as well as nitrates, often found in processed meat.
What’s more, among the genes that were most affected by the alkylation patterns were those that previous research has shown are among the most common drivers of colorectal cancer when they mutate.
– Moderation urged –
But Giannakis, also a practicing doctor, said it was important to focus on how the research can be used to help patients.
Identifying patients who have already started to accrue the mutational signature could help identify who’s at greater risk of developing cancer, or catch the disease at an earlier stage.
Finally, understanding the biological pathway through which colorectal cancer occurs paves the way for medicines that interrupt or reverse the process, preventing the disease.
High levels of tumor alkylation damage were only seen among patients eating on average more than 150 grams (five ounces) a day, roughly equal to two or more servings.