Cancer mortality by country of birth and cancer type in Sweden: A 25-year registry-based cohort study

Our plain-English summary of Cancer mortality by country of birth and cancer type in Sweden: A 25-year registry-based cohort study, by D.N. Tollosa, K. Zendehdel, A. Procopio, et al (Cancer Medicine, 2024).

The study

• Authors: D.N. Tollosa, K. Zendehdel, A. Procopio, A. Cederström, P. Boffetta, E. Pukkala, M. Rostila
• Journal: Cancer Medicine
• Published: 2024;13(14):e70020
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Numerous studies have reported lower overall cancer mortality rates among immigrants compared to native populations. However, limited information exists regarding cancer mortality among immigrants based on specific birth countries and cancer types. We used population-based registries and followed 10 million individuals aged 20 years or older in Sweden between 1992 and 2016. The Cox proportional hazard model was used to explore the disparities in cancer mortality by country of birth and cancer type, stratified by gender. Age-standardized mortality rates were also computed using the world standard population. Hazard ratio (HR) of all-site cancer was slightly lower among immigrants (males: HRm = 0.97: 95% confidence interval: 0.95, 0.98; females: HRf = 0.93: 0.91, 0.94) than Swedish-born population. However, the immigrants showed higher mortality for infection-related cancers, including liver (HRf = 1.10: 1.01, 1.19; HRm = 1.10: 1.02, 1.17), stomach (HRf = 1.39: 1.31, 1.49; HRm = 1.33: 1.26, 1.41) cancers, and tobacco-related cancers, including lung (HRm = 1.44: 1.40, 1.49), and laryngeal cancers (HRm = 1.47: 1.24, 1.75). The HR of mesothelioma was also significantly higher in immigrants (HRf = 1.44: 1.10, 1.90). Mortality from lung cancer was specifically higher in men from Nordic (HRm = 1.41: 1.27, 1.55) and non-Nordic Europe (HRm = 1.49: 1.43, 1.55) countries and lower in Asian (HRm = 0.78: 0.66, 0.93) and South American men (HRm = 0.70: 0.57, 0.87). In conclusion, there are large variations in cancer mortality by country of birth, and cancer type and require regular surveillance. Our detailed analyses lead to some novel findings such as excess mortality rate of mesothelioma and laryngeal cancers in Immigrants in Sweden. A targeted cancer prevention program among immigrants in Sweden is needed.

© 2024 The Author(s). Cancer Medicine published by John Wiley & Sons Ltd.

In plain English

This registry-based cohort study followed 10,011,841 people aged 20 or older living in Sweden from 1992 to 2016, 18% of them foreign-born. It compared cancer death rates of immigrants, by region and country of birth, with those of Swedish-born people, adjusting for age, education, income, marital status and calendar period. Overall, immigrants had slightly lower cancer mortality (women: hazard ratio 0.93, 95% CI 0.91 to 0.94; men: 0.97, 0.95 to 0.98). For mesothelioma, of unspecified site, immigrant women had a higher death rate (67 immigrant versus 347 Swedish-born deaths; hazard ratio 1.44, 1.10 to 1.90). For immigrant men (228 versus 1,851 deaths) the adjusted ratio, 1.06 (0.92 to 1.22), was not statistically significant. Men from Nordic countries had 1.26 (1.03 to 1.53), and the authors reported much higher ratios among Turkish-born men and women. Asbestos exposure was not measured. The authors suggested exposure before migration or in Swedish jobs such as construction and shipbuilding might contribute, and urged caution because deaths were few.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Registry-based open cohort study linking Swedish national registers; Cox proportional hazards models comparing immigrants with Swedish-born people
• Who was studied: 10,011,841 individuals aged 20 years or older residing in Sweden, followed 1992 to 2016; 18% foreign-born, 50.2% female (905,472 foreign-born and 4,139,762 Swedish-born men; 890,314 foreign-born and 4,076,293 Swedish-born women)
• Exposure: Country or region of birth (immigrant versus Swedish-born); no asbestos or other occupational exposure was measured. Models adjusted for age, education, income, marital status and calendar year.
• Main results:
  • All cancers combined: hazard ratio among immigrant women 0.93 (95% CI 0.91, 0.94) and among immigrant men 0.97 (0.95, 0.98), compared with Swedish-born individuals
  • Mesothelioma mortality was significantly higher in immigrant women than Swedish-born women (67 immigrant and 347 Swedish deaths; fully adjusted HR 1.44, 1.10 to 1.90)
  • Mesothelioma in immigrant men overall (228 immigrant and 1,851 Swedish deaths): age-adjusted HR 1.16 (1.01, 1.33), fully adjusted HR 1.06 (0.92, 1.22), not statistically significant
  • Mesothelioma by origin: male immigrants from Nordic countries HR 1.26 (1.03, 1.53); female immigrants from Denmark 2.96 (1.47, 5.98); Turkish-born men 11.92 (6.16, 23.06) and women 2.34 (1.35, 4.06), as stated in the text, though the HR labels there do not match the groups named
  • Lung cancer mortality was significantly higher in immigrant men (HR 1.44, 1.40 to 1.49); in immigrant women overall the fully adjusted HR was 0.99 (0.96, 1.03)
• The authors' conclusion: The authors concluded that immigrants overall had somewhat lower cancer mortality, but some groups had higher mortality, particularly for infection- and tobacco-related cancers. On mesothelioma, which they noted is primarily caused by asbestos, they suggested that asbestos exposure in Swedish industries after World War II, together with pre-migration exposure, might explain the excess, and they advised caution.
• Limitations the authors state:
  • The mesothelioma findings rest on a relatively low number of deaths
  • Immigrants returning to their birth country when seriously ill (salmon bias) could lead to underestimates of immigrant cancer mortality
  • Only socio-demographic confounders were used; health behaviors, genetic factors and environmental hazards were not accounted for
  • Only mortality data were used, not cancer incidence or survival

Topics

Medical terms in this study, explained in our Lexicon: Cohort Study, Hazard Ratio, confidence interval, Laryngeal Cancer, Mesothelioma, Lung Cancer.

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