Increased lung cancer risk due to residential radon in a pooled and extended analysis of studies in Germany

Our plain-English summary of Increased lung cancer risk due to residential radon in a pooled and extended analysis of studies in Germany, by H.E. Wichmann, A.S. Rosario, I.M. Heid, et al (Health Physics, 2005).

The study

• Authors: H.E. Wichmann, A.S. Rosario, I.M. Heid, M. Kreuzer, J. Heinrich, L. Kreienbrock
• Journal: Health Physics
• Published: 2005;88(1):71-9
• Cited by: 30 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Residential radon has been shown to be a risk factor for lung cancer in several studies-but with limited power in each single study. The data of two case-control studies performed during 1990-1997 in Germany and used for previous publications have been extended and pooled. Both studies have identical study designs. In total, data of 2,963 incident lung cancer cases and 4,232 population controls are analyzed here. One-year radon measurements were performed in houses occupied during the 5-35 y prior to the interview. Conditional logistic and linear relative risk regression was used for the analysis. Measurements covered on average 70% of the exposure time window, with an average radon exposure of 61 Bq m(-3). The smoking and asbestos-adjusted ORs were 0.97 [95% confidence interval (CI) 0.85 to 1.11] for 50-80 Bq m(-3), 1.06 (95% CI 0.87 to 1.30) for 80-140 Bq m(-3) and 1.40 (95% CI 1.03 to 1.89) for radon concentrations above 140 Bq m(-3), compared to the reference category <50 Bq m(-3). The linear increase in the odds ratio per 100 Bq m(-3) was 0.10 (95% CI -0.02 to 0.30) for all subjects and 0.14 (95% CI -0.03 to 0.55) for less mobile subjects who lived in only one home in the last 5-35 y. The risk coefficients generally were higher when measurement error in the radon concentrations was reduced by restricting the population. With respect to histopathology, the risk for small cell carcinoma was higher than for other subtypes. This analysis strengthens the evidence that residential radon is a relevant risk factor for lung cancer.

In plain English

This study pooled and extended two German case-control studies of lung cancer and radon gas in homes. One was in West Germany (1990–1996) and one in East Germany (1990–1997), and both used the same design. They included 2,963 people with newly diagnosed lung cancer and 4,232 population controls. Radon was measured in the living rooms and bedrooms of homes lived in 5 to 35 years before interview. Results were adjusted for smoking and for occupational asbestos exposure (ever or never); fiber types were not specified. Compared with radon below 50 Bq per cubic meter, the odds ratio for lung cancer above 140 Bq per cubic meter was 1.40 (95% CI 1.03 to 1.89). The two middle categories showed no clear increase. The overall trend estimate did not reach statistical significance. The increase appeared stronger for small cell carcinoma, and none was seen for adenocarcinoma. People ever occupationally exposed to asbestos had an odds ratio for lung cancer of 1.37 (95% CI 1.20 to 1.57), adjusted for smoking. The authors concluded that the analysis strengthens the evidence that residential radon is a relevant lung cancer risk factor. They noted low response among controls and gaps in radon measurements.

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: Pooled analysis of two population-based case-control studies with identical design (West and East Germany)
• Who was studied: 2,963 incident lung cancer cases aged 24–75 and 4,232 population controls. West Germany (1990–1996): 1,651 cases and 2,515 controls. East Germany (1990–1997): 1,312 cases and 1,717 controls. 82% of subjects were men.
• Exposure: Residential radon, measured with alpha-track detectors in the living room and bedroom and averaged over homes lived in 5–35 years before interview. The mean was 61 Bq per cubic meter in cases and 60 in controls. Occupational asbestos exposure, recorded only as ever or never with no fiber type given, was used as an adjustment variable and its own odds ratio was reported.
• Main results:
  • In all subjects, smoking- and asbestos-adjusted odds ratios compared with below 50 Bq per cubic meter were: 0.97 (95% CI 0.85 to 1.11) for 50–80, and 1.06 (95% CI 0.87 to 1.30) for 80–140 Bq per cubic meter.
  • Above 140 Bq per cubic meter, the odds ratio was 1.40 (95% CI 1.03 to 1.89), statistically significant. The comparison group was below 50 Bq per cubic meter, and 120 cases and 147 controls were in this top category.
  • For all 2,963 cases and 4,232 controls, the excess odds ratio per 100 Bq per cubic meter was 0.10. Its 95% CI was 0.02 to 0.30 as scanned; the lower limit is negative (-0.02 in the PubMed abstract), and the article says the pooled estimate was not statistically significant.
  • The West German study showed no increase in risk (excess odds ratio 0.02). The East German study showed an increased risk (excess odds ratio 0.17, CI 0.00 to 0.48). The difference between the two studies was not statistically significant.
  • Among less mobile subjects who lived in only one home in the 5–35 years before interview (780 cases and 942 controls), the excess odds ratio per 100 Bq per cubic meter rose to 0.14. The upper 95% confidence limit was 0.55; the lower limit's sign is lost in the scan (-0.03 in the PubMed abstract).
  • By tumor type, small cell carcinoma showed a significantly elevated risk (excess odds ratio 0.29, CI 0.04 to 0.78; 712 cases). Adenocarcinoma showed no increase.
  • Bedroom radon measurements gave an excess odds ratio of 0.13 (CI 0.00 to 0.33), compared with 0.04 for living room measurements.
  • The interaction between radon and smoking was close to multiplicative.
  • Occupational asbestos exposure (ever versus never) was associated with an odds ratio for lung cancer of 1.37 (95% CI 1.20 to 1.57), adjusted for smoking. This covered 780 exposed cases and 784 exposed controls.
• The authors' conclusion: The authors concluded that the analysis strengthens the evidence that residential radon is a relevant risk factor for lung cancer.
• Limitations the authors state:
  • Low radon concentrations in the West German study area reduced statistical power, also in the pooled analysis.
  • Response was low, especially among controls (40% of controls and 76% of cases).
  • 27% of cases and 8% of controls were excluded because radon measurements were missing.
  • 30% of the exposure window had no radon measurement and had to be filled in by imputation.
  • Radon effects may still be underestimated because the smoking effects may not have been fully captured.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Lung Cancer, Relative Risk, confidence interval, Odds Ratio, Histopathology, Carcinoma.

Related studies

• Case-control study on lung cancer and residential radon in western Germany — L. Kreienbrock, M. Kreuzer, et al. (2001)
• Residential radon and risk of lung cancer in Eastern Germany — M. Kreuzer, J. Heinrich, et al. (2003)
• Residential radon exposure and lung cancer--an epidemiological study of Norwegian municipalities — K. Magnus, A. Engeland, et al. (1994)
• Occupational lung cancer risk for men in Germany: results from a pooled case-control study — I. Brüske-Hohlfeld, M. Möhner, et al. (2000)
• Lung cancer and exposure to man-made vitreous fibers: results from a pooled case-control study in Germany — H. Pohlabeln, K.H. Jöckel, et al. (2000)
• Parental occupational exposure and risk of childhood central nervous system tumors: a pooled analysis of case-control studies from Germany, France, and the UK — C. Huoi, A. Olsson, et al. (2014)

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