1 in 3 people at risk of colorectal cancer from processed meat

One in three people carry a gene that increases the risk of colorectal cancer from the consumption of red meat and processed meat, according to a new study that was presented at the American Society of Human Genetics’ 2013 meeting.

The study, which is the first to identify the gene-diet interaction on a genome-wide scale, also reveals another specific genetic variation that appears to modify whether eating more vegetables, fruits and fibre lowers colorectal cancer risk.

“Diet is a modifiable risk factor for colorectal cancer,” said lead author Jane Figueiredo, PhD, Assistant Professor of Preventive Medicine at the Keck School of Medicine at the University of Southern California (USC).

“Our study is the first to understand whether some individuals are at higher or lower risk based on their genomic profile. This information can help us better understand the biology and maybe in the future lead to targeted prevention strategies.

“But we are not saying that if you don’t have the genetic variant that you should eat all the red meat you’d like.

“People with the genetic variant allele have an even higher increased risk of colorectal cancer if they consume high levels of processed meat, but the baseline risk associated with meat is already pretty bad.”

The researchers systematically searched the more than 2.7 million genetic sequences for interactions with consumption of red and processed meat. The study looked at 9287 patients with colorectal cancer and a control group of 9117 people without cancer.

The study found that the risk of colorectal cancer associated with processed meat was significantly higher among people with the genetic variant rs4143094. This variant is located on the same chromosome 10 region that includes GATA3, a transcription factor gene previously linked to several forms of cancer. The transcription factor encoded by this gene normally plays a role in the immune system, but carries this genetic variant in about 36% of the population.

The researchers speculate that the digestion of processed meat may promote an immunological or inflammatory response that may trigger tumour development. The GATA3 transcription factor normally would help suppress the immunological or inflammatory response. However, if the GATA3 gene region contains a genetic variant, it may encode a dysregulated transcription factor that impacts its ability to suppress the response.

The study is part of an ongoing collaboration among multiple institutions worldwide, including the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO).

“GECCO aims to continue to discover additional colorectal cancer-related variants by investigating how genetic variants are modified by other environmental and lifestyle risk factors, including biomarkers, as well as how they influence patient treatment response and survival,” said senior author Ulrike Peters, PhD, of the Fred Hutchinson Cancer Research Center’s Public Health Sciences Division.

“Colorectal cancer is a disease that is strongly influenced by certain types of diets,” Figueiredo said. “We’re showing the biological underpinnings of these correlations and trying to understand whether genetic variation may make some people more or less susceptible to certain carcinogens in food, which may have future important implications for prevention and population health.”