Purpose: Prostate cancer (PCa) incidence and prognosis vary geographically. We examined possible differences in PCa risk by clinical risk category between native-born and immigrant populations in Sweden. Our hypothesis was that lower PSA-testing uptake among foreign-born men would result in lower rates of localized disease, and similar or higher risk of metastatic disease.
Methods: Using the Prostate Cancer database Sweden, we identified 117,328 men with PCa diagnosed from 1991 to 2008, of which 8,332 were foreign born. For each case, 5 cancer-free matched controls were randomly selected from the population register. Conditional logistic regression was used to compare low risk, intermediate risk, high risk, regionally metastatic, and distant metastatic PCa based upon region of origin.
Results: Across all risk categories, immigrants had significantly lower PCa risk than native-born Swedish men, except North Americans and Northern Europeans. The lowest PCa risk was observed in men from the Middle East, Southern Europe, and Asia. Multivariable adjustment for socioeconomic factors and comorbidities did not materially change risk estimates. Older age at immigration and more recent arrival in Sweden were associated with lower PCa risk. Non-native men were less likely to be diagnosed with PCa through PSA testing during a health checkup.
Conclusions: The risk for all stages of PCa was lower among first-generation immigrants to Sweden compared with native-born men. Older age at immigration and more recent immigration were associated with particularly low risks. Patterns of PSA testing appeared to only partly explain the differences in PCa risk, since immigrant men also had a lower risk of metastatic disease.