Lifestyle factors play a much larger role than genetic risk in determining who gets colon and rectal cancer, according to a study that modeled cancer risk using both lifestyle and genetic information.
In addition to serving as a wake-up call for the realization that we have more influence over the risk of developing colon cancer than many previously assumed, the new model can also be used to stratify people according to their risk factors to make cancer screening more efficient.
The study, “Risk Model for Colorectal Cancer in Spanish Population Using Environmental and Genetic Factors: Results from the MCC-Spain study,” was published in the journal Scientific Reports.
“A risk model is a mathematical tool that allows us to predict who is most likely to suffer from a particular disease, in this case, colon cancer,” Dr. Victor Moreno, senior investigator of the study, said in a press release. Moreno is head of the Catalan Institute of Oncology’s Cancer Prevention and Control Program and a professor at the University of Barcelona Faculty of Medicine and Health Sciences.
Researchers collaborating across a number of Spanish research institutions used information from 10,106 participants included in a large multicenter study called MCC Spain. As part of the study, participants provided information about diet, physical exercise, body mass index, alcohol intake, and family history of cancer.
The study also included a subgroup of 1,336 colorectal cancer patients and 2,744 controls who provided blood samples to enable genetic testing.
The model showed that changing a risky lifestyle factor for the better, for instance switching to a healthy diet, can compensate for the effects of four mutations linked to cancer risk. So a person with plenty of genetic risk factors may never develop cancer if they lead a healthy lifestyle.
“This is important considering that lifestyle, unlike genetic traits, is somewhat modifiable, while genetic susceptibility is inherited from our parents,” said Dr. Gemma Ibañez, a digestologist at the Bellvitge Biomedical Research Institute in Spain, and first author of the study.
“In fact, the items we have identified as risk markers correlate with the recommendations set by the European Cancer Code to reduce the risk of cancer,” she said.
But the findings can also be used to improve current colon cancer screening practices. Today, age is the only factor considered when including patients in screening. Using information about genetic risk and lifestyle of individual patients would allow physicians to model cancer risks and help stratify patients as belonging to high- or low-risk groups.
With the data in hand, the research team is now focusing on its new study called COLSCREEN. It intends to examine how people view the prospect of getting a genetic test that would identify a risk for colon cancer.
“There are no studies that say what patients think about genetic tests, or whether they want to be informed of their chances of having certain diseases, and we think it is very relevant,” Ibañez said.