Red meat, family history, and increased risk of gastric cancer with microsatellite instability

Microsateliite instability (MSI) occurs frequently in sporadic gastric canc er (GC) and may define a distinctive molecular pathway of carcinogenesis. W e evaluated the role of dietary risk factors in GC according to MSI status. A large series of 382 GC cases and 561 controls were originally identified in a population-based case-control study carried out in the high-risk area around Florence, Italy; 126 GC patients were typed for MSI status. A MSIphenotype was detected in 43 of 126 cases (34.1%), whereas 83 cases were cl assified as MSI-. A multinomial logistic regression model was used to compa re the two subgroups of GC classified according to MSI status in the same a nalysis, with all of the available population controls. A case-case approac h was also used. The risk of MSI+ tumors was positively associated with hig h consumption of red meat and meat sauce and negatively associated with con sumption of white meat. A positive association was also seen with total pro tein and nitrite intake, whereas no relation was found with micronutrient i ntake. Risk was especially high among subjects reporting both a positive GC family history and a high consumption of red meat (odds ratio, 25.7; 958 c onfidence interval, 6.4-102.8), For MSI- tumors, a significant protective e ffect was associated with frequent consumption of citrus and other fresh fr uit, garlic, legumes, vegetables, and olive oil and with high intake of p-c arotene and other antioxidants and sugar, whereas positive associations wer e seen with protein and sodium intake. In summary, a specific dietary patte rn emerged for MSI+ gastric tumors, suggesting that factors related to red meat consumption are involved in this pathway, particularly among individua ls with a positive family history. In contrast, the risk of MSI- tumors was strongly reduced by the frequent consumption of fresh fruit and vegetables .