Can the frequency of meat consumption increase the risk of colon cancer?

In a study recently published in the journal Nutritional values, Researchers examined the associations between red and processed meat consumption and the resulting risk of colorectal neoplasia. This significant research adds to the limited evidence by focusing on the joint effects of meat consumption and genetic predisposition on disease risk. The study used data from screening colonoscopies of 7,291 participants and genotyping information from a subset of 4,774 participants.

The results of the study showed that while red meat was not statistically associated with an increased risk of colorectal neoplasia, processed meat significantly increased the subsequent risk of the disease. In particular, consumption of processed meat more than once per week was associated with an increased risk of colorectal neoplasia, corresponding to a 19th percentile higher polygenic risk score (PRS). This highlights the importance of limiting processed meat consumption as a health behavior that can counteract a genetic predisposition to colorectal neoplasia.

Study: Red and processed meat consumption, polygenic risk, and prevalence of colorectal neoplasia: results from a screening colonoscopy population. Image credit: Hakase_420 / Shutterstock

background

Colorectal cancer (CRC), also called colon cancer, is an abnormal growth of tissue (“polyps”) on the inner lining of the colon or rectum. It is a serious and often fatal disease that is the second leading cause of cancer-related death worldwide. Worryingly, the incidence of CRC is increasing at an unprecedented rate, with approximately 2 million new cases and 1 million deaths recorded each year.

Fortunately, colon cancer usually begins as benign polyps and can take ten years or more to develop into malignant tumors, highlighting the life-saving potential of early detection and regular screening.

Previous studies have identified genetics and diet as two major factors in colorectal cancer risk. The International Agency for Research on Cancer has identified red and processed meat in particular as carcinogenic. However, despite the existing studies on independent risks, there is little evidence of the joint effects of genetics and meat consumption on colorectal cancer risk.

About the study

The present study aims to fill this gap in the literature by using the recently developed measure of genetic risk equivalent (GRE) to elucidate whether meat consumption (as a function of frequency per week) can amplify or offset the risks associated with genetic predispositions.

Data for the study were collected from the accompanying evaluation of innovative test procedures for colorectal cancer early detection (BliTz), a large noninvasive German CRC screening study for men and women over 50 between 2002 and 2019 (n = 11,104). Inclusion criteria for the study included complete socioeconomic, lifestyle, demographic, medical and family CRC histories (obtained from medical records and questionnaires completed by participants).

All participants underwent routine colonoscopy and associated histology. CRC (or precancerous lesions) were identified based on the presence and progression of adenomas. Participants with confirmed CRC (or its precursors) underwent genotyping, along with a random subset of healthy individuals for comparison. Genotyping data were used to calculate polygenic risk scores (PRS). Questionnaires were used to record participants’ diet in the year before the study, focusing on the frequency of red or processed meat consumption.

“The frequency was initially divided into two levels: ≤1 time/week and >1 time/week, and the frequency >1 time/week was further divided into two levels: >1 time/week and

Statistical analysis included chi-square tests to compare participants with and without CRC or its precursors. Multiple logistic regressions were then performed, adjusting for educational level, age, sex, body mass index (BMI), smoking and alcohol consumption status, chronic diseases, and physical activity level. The regression coefficients and adjusted odds ratios (ORs) derived from these models were used to calculate GREs, which serve as the outcome of interest in this study.

Study results

Of the 11,104 participants in the BliTz study, 7,291 met the inclusion criteria of the present study and were considered for further analyses. Histological examinations revealed that 2,427 participants had colorectal neoplasia, of which 877 had advanced precancerous lesions and 68 had CRC. All of these participants underwent genotyping. In addition, 2,559 participants without colorectal neoplasia were genotyped for study comparisons.

The results showed that processed meat and genetic predisposition were independently associated with higher GRE scores and thus the likelihood of colorectal neoplasia. When analyzed together, consumption of processed meat more than once per week increased GRE scores, corresponding to a 19% higher PRS (GRE = 19.0, aOR = 1.28), indicating a significant impact of dietary habits on subsequent CRC risk. Among individuals in the highest PRS risk quartile, this risk increased by 2.3- to 3.8-fold.

Surprisingly, the association between red meat consumption and CRC risk did not reach statistical significance regardless of consumption frequency.

Conclusions

The present study is a valuable contribution to the literature as it is the first to examine the joint associations between genetic predisposition and meat consumption with regard to the later risk of CRC or its precursors. Study results from a cohort of more than 7,000 German adults showed that consumption of processed meat more than once per week increased GRE scores, which corresponds to a 19th percentile higher PRS score. In contrast to previous studies, consumption of red meat was not associated with an increased risk of CRC.

Taken together, these findings underscore the role of diet in colorectal neoplasia and highlight the potential of interventions to eliminate processed meat to compensate for high susceptibility to the deadly disease.