A meta-analysis of 6 cohort and 28 case-control studies demonstrated a significant association between higher red meat intake and the risk of lung cancer (RR, 1.44; 95% CI, 1.29-1.61), though the heterogeneity of the studies was high (I2 = 77%).8 Higher beef intake was also associated with an increased risk of lung cancer (RR, 1.39; 95% CI, 1.14-1.69), but not lamb or pork, with no significant heterogeneity among these studies. A more recent meta-analysis also found a significant increase in the risk of lung cancer with higher red meat intake (SRRE, 1.24; 95% CI, 1.01-1.51), but without significant heterogeneity.9
In a meta-analysis of 46 prospective studies, the risk of breast cancer significantly increased per serving (120 g) of total red meat (RR, 1.07; 95% CI, 1.01-1.14; I2 = 7.1%) and fresh red meat (RR, 1.13; 95% CI, 1.01-1.26; I2 = 56.4%).10 High total or fresh red meat consumption, however, did not significantly increase the risk of breast cancer compared with low consumption.
A meta-analysis of 4 prospective and 16 case-control studies found that higher red meat consumption was significantly associated with an increased risk of non-Hodgkin lymphoma (NHL), with a summary relative risk (SRR) of 1.32 (95% CI, 1.12-1.55) compared with lower intakes.11 When the study types were assessed separately, only case-control studies demonstrated the association (SRR, 1.11; 95% CI, 1.04-1.18).
Another meta-analysis of 14 studies demonstrated a significant association between higher red meat intake and the risk of NHL among case-control studies, but not among cohort studies.12
In another meta-analysis, which included 14 studies, there was a significant increase in NHL risk associated with higher red meat consumption (SRR, 1.22; 95% CI, 1.03-1.44; I2 = 35%), but no such connection was found with multiple myeloma, diffuse large B cell lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, or follicular lymphoma when analyzed alone.13 This study did not separately assess cohort and case-control studies.
Red meat (RR, 1.45; 95% CI, 1.22-1.73) and beef (RR, 1.28; 95% CI, 1.04-1.57) intake were significantly associated with an increased risk of gastric cancer in a meta-analysis of 42 studies.14 This association was driven by the case-control studies (RR, 1.63; 95% CI, 1.33-1.99), as the association was not observed in the cohort studies alone. This was consistent with another meta-analysis of 42 studies, in which greater consumption of red meat was significantly associated with gastric cancer (RR, 1.67; 95% CI, 1.36-2.05) in case-control studies, but there was no significant association among the cohort studies.15