Consumption of red and processed meat and breast cancer incidence: A systematic review and meta-analysis of prospective studies

Abstract

Prior studies on red and processed meat consumption with breast cancer risk have generated inconsistent results. We performed a systematic review and meta-analysis of prospective studies to summarize the evidence regarding the relation of red meat and processed meat consumption with breast cancer incidence. We searched in MEDLINE and EMBASE databases through January 2018 for prospective studies that reported the association between red meat and processed meat consumption with incident breast cancer. The multivariable-adjusted relative risk (RR) was combined comparing the highest with the lowest category of red meat (unprocessed) and processed meat consumption using a random-effect meta-analysis. We identified 13 cohort, 3 nested case-control and two clinical trial studies. Comparing the highest to the lowest category, red meat (unprocessed) consumption was associated with a 6% higher breast cancer risk (pooled RR,1.06; 95% confidence intervals (95%CI):0.99-1.14; I² = 56.3%), and processed meat consumption was associated with a 9% higher breast cancer risk (pooled RR, 1.09; 95%CI, 1.03-1.16; I² = 44.4%). In addition, we identified two nested case-control studies evaluating the association between red meat and breast cancer stratified by N-acetyltransferase 2 acetylator genotype. We did not observe any association among those with either fast (per 25 g/day pooled odds ratio (OR), 1.18; 95%CI, 0.93-1.50) or slow N-acetyltransferase 2 acetylators (per 25 g/day pooled OR, 0.99; 95%CI, 0.91-1.08). In the prospective observational studies, high processed meat consumption was associated with increased breast cancer risk.

Keywords: N-acetyltransferase 2 acetylators; breast cancer; meta-analysis; processed meat; red meat.

Figure 1.

Search, screening and selection process of prospective cohort studies of red meat and processed meat intake and risk of breast cancer.

Figure 2.

Red meat intake and relative risks of overall breast cancer (highest category vs. lowest category). BWHS, Black Women Health Study; CNBSS, Canadian National Breast Screening Study; CSA, California Seventh-day Adventist; EPIC, European Prospective Investigation into Cancer and Nutrition cohort; MPCDRF, the Monitoring Project on Cardiovascular Disease Risk Factors; NHSII, Nurses’ Health Study II; NIH-AARP, National Institute of Health- the American Association of Retired Persons; NLCS, The Netherland Cohort Study; SMC, Swedish Mammography Cohort; SU.VI.MAX, Supplemental en Vitamines et Mineraux Antioxydants; UKWCS, The UK Women’s Cohort Study.

Figure 3.

Processed meat intake and relative risks of overall breast cancer (highest category vs. lowest category). BWHS, Black Women Health Study; EPIC, European Prospective Investigation into Cancer and Nutrition cohort; MDC, the Malmö Diet and Cancer; MPCDRF, the Monitoring Project on Cardiovascular Disease Risk Factors; NHS, Nurses’ Health Study; NHSII, Nurses’ Health Study II; NIH-AARP, National Institute of Health- the American Association of Retired Persons; NLCS, The Netherland Cohort Study; PLCOCST, Prostate Lung Colorectal and Ovarian Cancer Screening Trial; RERFLSS, The Radiation Effects Research Foundation’s Life Span Study; SMC, Swedish Mammography Cohort; SU.VI.MAX, Supplemental en Vitamines et Mineraux Antioxydants; UKWCS, The UK Women’s Cohort Study.

Figure 4.

Total red meat intake and relative risks of overall breast cancer (highest category vs. lowest category). NHS, Nurses’ Health Study; NHSII, Nurses’ Health Study II; NIH-AARP, National Institute of Health- the American Association of Retired Persons; NYS, The New York University Women’s Health Study; PLCOCST, Prostate Lung Colorectal and Ovarian Cancer Screening Trial; SMC, Swedish Mammography Cohort.

Figure 5.

Red meat intake and risk of breast cancer based on NAT2 acetylator genotype (per 25 g/day). DCH, Diet, Cancer, and Health Study; NHS, Nurses’ Health Study.