Gender perspectives on the relationship between red and processed meat intake and colorectal cancer: a systematic review and meta‐analysis
Authors: Lee Hannah , Lee Jung Eun , Kang Minji , Shim Jae Eun , Paik Hee Young 
Published: November 2023

The International Agency for Research on Cancer (IARC) classified red meat intake as probably carcinogenic and processed meat intake as carcinogenic to humans through a review of epidemiologic and mechanistic evidences1. In the epidemiologic studies, red meat intake has been often assessed in the food frequency questionnaire (FFQ). The process of the development of FFQs includes the selection of food items and portion sizes. Although food preference and portion sizes vary by gender, gender differences are not often considered in the FFQ development2. Therefore, we compared the results of cohort studies on red and processed meat intake and colorectal cancer according to the gender consideration during the FFQ development.We identified studies that examined the association between red meat or processed meat intake and colorectal cancer by searching the database of PubMed published up to March 2016. The studies identified were categorized into “Gender‐specific (GS) group” if studies used FFQs developed based on gender‐specific data. Otherwise, studies were categorized into “Not gender‐specific (NGS) group”. Using a random‐effects model, we combined the study‐specific multivariate relative risk (RR)s and 95% confidence interval (CI)s, comparing the highest and the lowest categories of red or processed meat intake. We then compared the combined estimates between GS group and NGS group using a meta‐regression model. Total number of studies included in meta‐analysis was 26. All analyses were conducted using Stata, version 10.1 (StataCorp., College Station, TX, USA). P < 0.05 considered statistically significant.Red meat intake was significantly associated with colorectal or colon cancer risk in GS group (RR=1.18, CI=1.01 to 1.35), but not in NGS group (RR=1.00, CI=0.90 to 1.10) (P for difference = 0.021). Similarly, when we limited our analysis to women only, we observed a significant positive association between red meat intake and colorectal or colon cancer risk in GS group (RR=1.24, CI=1.03 to 1.45), but not in NGS group (RR=0.81, CI=0.60 to 1.02) (P for difference=0.006). However, the associations were not clear in either GS or NGS groups among men. For processed meat, increased risk of colorectal or colon cancer was observed comparing high with low categories in both GS and NGS groups, but the associations between GS and NGS group were not statistically different in men and women combined, men alone or women alone. Red and processed meat intake was significantly associated with an increased risk of colorectal or colon cancer in GS group (RR=1.17, CI=1.06 to 1.28), but not in NGS group (RR=1.25, CI=0.87 to 1.62) (P for difference = 0.098).The consideration of gender in the development of dietary assessment tools may enhance accuracy of the nutritional epidemiologic studies.Support or Funding InformationThis research was supported by Support Program for Women in Science, Engineering and Technology through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (Grant no. 2016H1C3A1903202).