PURPOSE: Different prostate cancer mortality rates observed in European countries may depend on cultural background. We aimed at exploring variation in prostate cancer mortality in the language regions of Switzerland as a function of "Italianity", a proxy for adherence to an Italian lifestyle.
METHODS: We used data of the Swiss National Cohort, a census-based record linkage study, consisting of census (1990 and 2000) and mortality (until 2008) data. 1,163,271 Swiss and Italian nationals 40+-year old were included. Multivariate age-standardized prostate cancer mortality rates and hazard ratios (HR) from Cox proportional hazards regression analysis were performed. Italianity was defined by an individual's nationality, place of birth and principal language, resulting in a score of 0-3 points.
RESULTS: Age-standardized prostate cancer mortality rates (per 100,000 person-years) were lowest in the Italian-speaking region of Switzerland (66.7 vs. 87.3 in the German-speaking region). Both Italian nationality and/or place of birth were significantly associated with lower mortality. There was a graded inverse association between mortality rates and increasing Italianity score. Individuals with the highest level of Italianity had a HR of 0.67 (95 % CI 0.59-0.76) compared to those with an Italianity score of zero. Results were similar when looking at language regions separately.
CONCLUSIONS: The strong and consistent association between Italianity and prostate cancer mortality suggests protective properties of an Italian lifestyle. Further research is required in order to determine which factors specific for Italian culture are responsible for the lower prostate cancer mortality.