Abstract
Although the association between red meat consumption and colorectal cancer (CRC) is well established, the association across subsites of the colon and rectum remains uncertain, as does time of consumption in relation to cancer development. As these relationships are key for understanding the pathogenesis of CRC, they were examined in two large cohorts with repeated dietary measures over time, the Nurses’ Health Study (n = 87,108 women, 1980–2010) and Health Professionals Follow-up Study (n = 47,389 men, 1986–2010). Cox proportional hazards regression models generated hazard ratios (HRs) and 95% confidence intervals (CIs), which were pooled by random-effects meta-analysis. In combined cohorts, there were 2,731 CRC cases (1,151 proximal colon, 816 distal colon, and 589 rectum). In pooled analyses, processed red meat was positively associated with CRC risk (per 1 serving/day increase: HR = 1.15, 95% CI: 1.01–1.32; P for trend 0.03) and particularly with distal colon cancer (per 1 serving/day increase; HR = 1.36; 95% CI: 1.09–1.69; P for trend 0.006). Recent consumption of processed meat (within the past 4 years) was not associated with distal cancer. Unprocessed red meat was inversely associated with risk of distal colon cancer and a weak non-significant positive association between unprocessed red meat and proximal cancer was observed (per 1 serving/day increase: distal HR = 0.75; 95% CI: 0.68–0.82; P for trend <0.001; proximal HR = 1.14, 95% CI: 0.92–1.40; P for trend 0.22). Thus, in these two large cohorts of US health professionals, processed meat intake was positively associated with risk of CRC, particularly distal cancer, with little evidence that higher intake of unprocessed red meat substantially increased risk of CRC. Future studies, particularly those with sufficient sample size to assess associations by subsites across the colon are needed to confirm these findings and elucidate potentially distinct mechanisms underlying the relationship between processed meat and subtypes of unprocessed red meat with CRC.
Highlights
As colorectal cancer (CRC) is the third most common cancer worldwide following lung and breast cancer, and the fourth most common cause of cancer death after lung, stomach, and liver cancer, identifying strategies to reduce its incidence is paramount [1]
When risk estimates were pooled for each subsite, in age-adjusted models higher consumption of unprocessed red meat was associated with a higher risk of proximal colon cancer (HR, 95% confidence intervals (CIs): 1.25, 1.06–1.47) but the association was attenuated and became non-significant after multivariable adjustment (HR, 95% CI: 1.14, 0.92–1.40) (Table 3)
Unprocessed red meat was not associated with distal colon cancer in age-adjusted models but after multivariable adjustment a significant inverse association was observed with distal colon cancer (HR, 95% CI: 0.75, 0.68–0.82; P for heterogeneity = 0.06)
Summary
As colorectal cancer (CRC) is the third most common cancer worldwide following lung and breast cancer, and the fourth most common cause of cancer death after lung, stomach, and liver cancer, identifying strategies to reduce its incidence is paramount [1]. Red and processed meat consumption have been associated with an increased risk of CRC in many observational studies and reducing, or eliminating, their intake may prevent CRC development [2,3,4,5]. Evidence on the relation between red meat and CRC risk by subsite location and time of intake has been limited. In order to better understand the association between unprocessed and processed red meat and CRC risk by tumor subsite location and time of red meat intake, we returned to our two prospective cohorts of U.S men and women
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
