Coffee consumption and risk of non-Hodgkin's lymphoma: evidence from the Italian multicentre case-control study

Several investigations have analysed the association between coffee intake and risk of cancer. Contradictory results were reported by the studies conducted in non-Hodgkin's lymphomas (NHL) few of which report results according to main NHL subgroups. The present study is aimed at evaluating the association between coffee consumption and the risk of NHL by analysing data from a large Italian multicentre case-control study that included 1,418 interviewed cases (1,301 B cell and 117 T cell NHL), diagnosed between 1990 and 1993, and 1,774 population healthy controls. The association was evaluated by standard logistic regression analysis. Odds ratio (OR) estimates were adjusted for gender, age, residence area, educational level, previous chemotherapy treatment, smoking habit and exposure to electromagnetic fields, radiation, pesticides and aromatic hydrocarbons. For all B cell lymphomas, an increased risk (OR 1.6, 95% CI 1.2-2.0) was observed in the highest exposure category (consumption > 4 cups per day for at least 30 years), but without a clear dose-response trend. Subgroup analyses highlighted an increased risk for drinkers of at least four cups per day for follicular lymphoma (OR 2.0, 95% CI 1.2-3.4). The risk increased with years of exposure and was more elevated among current smokers. Consumption of more than four cups of coffee per day enhances the risk of lymphoma, especially the follicular subtype. Further investigations based on large cohorts and accurate measures of exposure are needed to confirm the observed associations.