Can how often you eat meat raise your risk of colorectal cancer?

In a recent study published in the journal Nutrients, researchers investigated the associations between red- and processed meat consumption and the subsequent risk of colorectal neoplasms. This significant research contributes to the limited body of evidence by focusing on the joint effects of meat consumption and genetic predisposition on the disease risk. Screening colonoscopy data from 7,291 participants and genotyping information from a subset of 4,774 participants were used for the study.

Study findings revealed that while red meats were not statistically associated with an increased risk of colorectal neoplasms, processed meats significantly heightened subsequent risks of developing the condition. Specifically, consuming processed meats more than once per week was associated with an increase in colorectal neoplasm risk, equivalent to having a 19 percentile higher polygenic risk score (PRS). This underscores the importance of limiting processed meat intake as a health behavior that may offset genetic predisposition to colorectal neoplasms.

Study: Red and Processed Meat Intake, Polygenic Risk and the Prevalence of Colorectal Neoplasms: Results from a Screening Colonoscopy Population. Image Credit: Hakase_420 / Shutterstock

Background

Colorectal cancer (CRC), also called ‘colon’ cancer, is abnormal tissue growth (‘polyps’) on the inner lining of the colon or rectum. It is a severe and often lethal condition, ranking second as the most frequent cause of cancer-related mortality worldwide. Alarmingly, the incidence of CRC is rising at unprecedented rates, with about 2 million new cases and 1 million deaths recorded each year.

Encouragingly, CRC usually begins as benign polyps, and their development into malignant tumors may take ten years or more, emphasizing the life-saving potential of early detection and frequent screening.

Previous research has identified genetic predisposition and diet as two main contributors to CRC risk. The International Agency for Research on Cancer has particularly classified red- and processed meats as carcinogens. However, despite the existing studies on independent risks, evidence on the joint effects of genetic predisposition and meat consumption on CRC risk has been limited.

About the study

The present study aims to bridge this gap in the literature by elucidating if meat consumption (as a function of frequency per week) can bolster or offset the risks posed by genetic predispositions by using the recently developed ‘genetic risk equivalent (GRE)’ metric.

Data for the study was collected from the Begleitende Evaluierung innovativer Testverfahren zur Darmkrebsfrüherkennung (BliTz) large cohort non-invasive German CRC screening study for men and women older than 50 between 2002 and 2019 (n = 11,104). Study inclusion criteria included completed socioeconomic, lifestyle, demographic, medical, and family CRC histories (obtained from medical records and participant-filled questionnaires).

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

“The frequency was first categorized into 2 levels: ≤1 time/week and >1 time/week, and frequency >1 time/week was further divided into 2 levels: >1 time/week and <1 time/day, and ≥1 time/day to evaluate the individual association of processed meat intake and the risk of colorectal neoplasm.”

Statistical analysis included Chi-squared tests to compare participants with and without CRC or its precursors. Multiple logistic regressions corrected for education level, age, sex, body mass index [BMI], smoking and alcohol consumption status, chronic disease, and physical activity level were then employed. The regression coefficients and adjusted odds ratios (ORs) derived from these models were used to compute GREs, which serve as the outcome of interest in this study.

Study findings

Of the 11,104 participants from the BliTz study, 7291 met the present study inclusion criteria and were included for further analyses. Histological examinations revealed that 2,427 participants had colorectal neoplasms, of which 877 had advanced precancerous lesions and 68 had CRC. All these participants were subjected to genotyping. Additionally, 2,559 participants without colorectal neoplasms were genotyped for the study comparisons.

Results indicated that processed meats and genetic predisposition were independently associated with higher GRE scores and, in turn, the likelihood of colorectal neoplasms. When analyzed together, processed meat consumption higher than once per week increased GRE scores equivalent to a 19% higher PRS (GRE = 19.0, aOR = 1.28), indicating a profound impact of dietary choices on subsequent CRC risk. In individuals at 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, irrespective of consumption frequency.

Conclusions

The present study is a valuable contribution to the literature, as it is the first to evaluate the joint associations of genetic predisposition and meat consumption on the subsequent risk of CRC or its precursors. Study findings on a cohort of more than 7,000 German adults revealed that processed meat consumption higher than once/week increased GRE scores equivalent to a 19 percentile higher PRS. In contrast to previous research, red meat consumption was not associated with increased CRC risk.

Together, these findings highlight the role of diet in colorectal neoplasms and underscore the potential for anti-processed meat interventions as compensation for a high predisposition to the deadly disease.