Cancer incidence in urban, rural, and densely populated districts close to core cities in Bavaria, Germany

Our plain-English summary of Cancer incidence in urban, rural, and densely populated districts close to core cities in Bavaria, Germany, by M. Radespiel-Tröger, K. Geiss, D. Twardella, et al (International Archives of Occupational and Environmental Health, 2018).

The study

• Authors: M. Radespiel-Tröger, K. Geiss, D. Twardella, W. Maier, M. Meyer
• Journal: International Archives of Occupational and Environmental Health
• Published: 2018;91(2):155-174
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: An ecologic study on the level of districts was performed to evaluate the possible association between district type and risk of cancer in Bavaria, Southern Germany.

Methods: Cancer incidence data for the years 2003-2012 were obtained from the population-based cancer registry Bavaria according to sex and cancer site. Data on district type, socio-economic area deprivation, particulate matter exposure, tobacco consumption, and alcohol consumption were obtained from publicly available sources. The possible association between district type and cancer risk adjusted for age, socio-economic area deprivation, particulate matter exposure, tobacco consumption, and alcohol consumption was evaluated using multivariable multi-level negative binomial regression.

Results: We found a significantly reduced cancer risk in densely populated districts close to core cities and/or rural districts compared to core cities with respect to the cancer sites mouth and pharynx (women only), liver (both sexes), larynx (both sexes), lung (both sexes), melanoma of the skin (both sexes), mesothelioma (men only), connective and soft tissue (both sexes), corpus uteri, other urinary tract (men only), urinary bladder (both sexes), and non-Hodgkin lymphoma (both sexes).

Conclusion: Our findings require further monitoring. Since the apparently increased cancer risk in core cities may be related to lifestyle factors, preventive measures against lifestyle-related cancer could be specifically targeted at populations in deprived core cities.

In plain English

This ecologic study compared cancer cases across whole districts rather than individual people. It covered all 96 districts of Bavaria, Germany, from 2003 to 2012, grouped as core cities, densely populated districts close to core cities, or rural districts. Depending on cancer site, they adjusted for age and selected district measures: deprivation, air pollution from particles up to 10 micrometres, and lung cancer and chronic liver disease death rates as stand-ins for smoking and drinking. The mesothelioma analysis adjusted for age and lung cancer death rates. Asbestos exposure was not measured. Among men, mesothelioma (1,585 cases, all sites counted together) was less common in rural districts than in core cities (adjusted risk ratio 0.72, 95% CI 0.60 to 0.85). The lower figure in districts near core cities was not statistically significant. Among women (385 cases), no significant difference was found. The authors suggested the lower risk for men outside cities might possibly reflect more workplace asbestos exposure in urban factories before Germany's 1993 ban. They noted results applied to districts, not individuals. They concluded that the findings require further monitoring.

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: Ecologic study at the level of districts, using population-based cancer registry data and multi-level negative binomial regression
• Who was studied: Residents of all 96 Bavarian districts (about 12.5 million people), 2003 to 2012. This was 61,260,383 person-years at risk in men and 63,706,719 in women. There were 370,856 invasive cancer cases in men and 328,198 in women.
• Exposure: District type (core city, densely populated outer conurbation, rural). Models were adjusted for age plus district-level predictors chosen separately for each cancer site from: deprivation index, PM-10 air pollution (particles 10 µm or less), and lung cancer and chronic liver disease mortality as proxies for tobacco and alcohol. The deprivation index was left out whenever a mortality proxy was included. The mesothelioma model included age and lung cancer mortality. Asbestos exposure was not measured. Mesothelioma was analysed as one category (ICD-10 C45), not split by site.
• Main results:
  • Men, mesothelioma, rural districts compared with core cities: risk ratio 0.72 (95% CI 0.61 to 0.85) adjusted for age only, and 0.72 (95% CI 0.60 to 0.85) after multivariable adjustment. Based on 718 rural and 404 core-city cases out of 1,585 total.
  • Men, mesothelioma, densely populated districts near core cities compared with core cities: multivariable risk ratio 0.90 (95% CI 0.74 to 1.10), not statistically significant.
  • Women, mesothelioma (385 cases): no significant difference by district type. Rural compared with core cities, multivariable risk ratio 1.20 (95% CI 0.84 to 1.72).
  • After multivariable adjustment, rural districts had significantly reduced risk compared with core cities for six cancer sites: liver (men), melanoma (both sexes), mesothelioma (men), connective and soft tissue (both sexes), other urinary tract (men), and non-Hodgkin lymphoma (both sexes).
  • The authors suggested the different mesothelioma risk was possibly related to occupational factors. In their discussion they pointed to a higher probability of occupational asbestos exposure in urban factories before Germany's 1993 ban.
• The authors' conclusion: The authors concluded that their findings require further monitoring, and that prevention of lifestyle-related cancer could be targeted at populations in deprived core cities.
• Limitations the authors state:
  • Because of the ecologic design, results apply only to districts, not to individuals.
  • There were no individual data on potential confounders such as tobacco consumption.
  • The reference years for deprivation (2006) and PM-10 (2000) may only approximately reflect exposure over the roughly 30-year cancer induction period.
  • People moving into, out of, or within Bavaria before diagnosis may have biased the estimates.

Topics

Medical terms in this study, explained in our Lexicon: Cancer Registry, Mesothelioma.

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