Food groups and risk of non-Hodgkin lymphoma: a multicenter, case-control study in Italy.

Incidence of non-Hodgkin lymphoma (NHL) has been rising worldwide, but the reasons are undefined. Dietary habits may play a role in the etiology of NHL by influencing the metabolic pathways of several cells of the immune system. This case-control study investigated the relation between food consumption and NHL risk. Between 1999 and 2002, we conducted a hospital-based case-control study on NHL in 2 areas of Italy. Cases were 190 patients (median age 58 years) with incident NHL admitted to specialized and general hospitals. Controls were 484 patients (median age 63 years) with acute non-neoplastic conditions admitted to the same hospitals network of cases. A validated food-frequency questionnaire was used to assess habitual diet 2 years before interview. Unconditional multiple logistic regression was used to estimate the odds ratios (OR) and the corresponding 95% confidence intervals (CI), with allowance for energy intake, according to the residual model. Consumption of highest versus lowest quartile of pasta/rice (OR = 1.87, 95% CI: 1.04-3.36) and cheese (OR = 1.66, 95% CI: 0.98-2.83) were associated with a significantly increased NHL risk. Inverse association was found for vegetables (OR = 0.49, 95% CI: 0.28-0.87), fruits (OR = 0.51, 95% CI: 0.30-0.85), and egg consumption (OR = 0.59, 95% CI: 0.36-0.97). The association of pasta/rice was also supported by an increased risk of high glycemic load levels (OR = 1.86, 95% CI: 1.04-3.32). In conclusion, our results suggested that diet could affect NHL risk.