For the first time, high consumption of processed and unprocessed red meat has been associated with DNA damage in patients with colorectal cancer. The study, published in Cancer Discovery – scientific journal ofAmerican Association for Cancer Research – and led by Marios Giannakis, professor of medicine at Harvard Medical School and oncologist at the Dana-Farber Cancer Institute, thus provides a possible explanation for what many epidemiological studies have been showing for some time.
The data that was missing
High consumption of red meat and processed meats such as sausages are now considered a risk factor for this cancer, which is among the most diagnosed in the world and the second most frequent in our country. In 2015, theInternational Agency for Research on Cancer (IARC) listed red meat as a human carcinogen, however, raising not a few controversies: studies on the subject have continued to follow one another, now confirming, now questioning the conclusion of the IARC. Experiments in animal models also suggested that red meat may promote the formation of colorectal cancer compounds, but there was a lack of evidence of what the molecular mechanism behind tumor development might be. The new study tries to fill this gap, at least in part: “We have identified for the first time a set of mutations in colorectal cancers collected from patients that are associated with a high consumption of red meat before diagnosis,” he says. to Salute Giannakis: “Our results support a possible carcinogenic role of this food in the development of colorectal cancer”.
Colorectal cancer: Red meat also puts young people at risk
by Tiziana Moriconi
The study: which meat and how much?
The research involved 900 patients. “One of the strengths of the study is the quality of the information on the diet we obtained – underlines Giannakis – which was collected prospectively, that is, not a posteriori and therefore without errors due to untrue memories, through widely validated questionnaires”. The median red meat consumption of these patients before the disease was 150 grams per day. Within the questionnaires, the questions concerned the consumption of “beef or lamb as a main course”, “pork as a main course”, “hamburger”, “sandwich or mixed dishes with beef, pork or lamb” with regard to non-red meats. processed, and of “bacon”, “beef or pork hot dogs”, “sandwiches with salami, mortadella or other cured meats” and “other processed meat such as sausage, kielbasa, etc. for processed meats.
Colorectal cancer: Red meat also puts young people at risk
by Tiziana Moriconi
The association between red meat and mutations
The set of identified mutations can be traced back to what biologists call damage by alkylation, already observed in animal models, probably due to nitrogen compounds and / or iron. “In our study – continues the researcher – the patients who reported a higher consumption of red meat are those who showed more damage to DNA of this type. Furthermore, these mutations are more present in tumors of the left final part of the colon, the same ones for which the epidemiological association is also stronger ”. However, no association emerged with the consumption of chicken and fish.
The analysis shows that DNA damage can affect the KRAS gene, in particular for two mutations (G12D e G13D) and the gene PIK3CA, both already associated with colorectal cancer. But the conditional continues to be a must also for Giannakis, because the concatenation of possible causal events is in any case long: “Formally we have observed the association between red meat and alkylation mutations. Then we know that these mutations have an impact on the KRAS gene and that the KRAS mutation can cause cancer ”.
Cancer, complex and multifactorial diseases
Obviously, there could also be other factors, in addition, that contribute to the development of the disease, also because the consumption of red meat, alone, does not account for all the damage to the DNA from alkylation observed in the research. There may also be genetic factors that increase or decrease the amount of damage that different individuals accumulate for the same amount of red meat consumed. The bottom line is the same: further studies are needed to understand the compressed biology behind the development of complex diseases such as cancer. However, these data add something new to the scientific debate on prevention: they support the role of red meat as a risk factor for colorectal cancer from a new point of view and indicate a direction in which to continue looking.
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