Case-control study on lung cancer and residential radon in western Germany

Our plain-English summary of Case-control study on lung cancer and residential radon in western Germany, by L. Kreienbrock, M. Kreuzer, M. Gerken, et al (American Journal of Epidemiology, 2001).

The study

• Authors: L. Kreienbrock, M. Kreuzer, M. Gerken, G. Dingerkus, J. Wellmann, G. Keller, H.E. Wichmann
• Journal: American Journal of Epidemiology
• Published: 2001;153(1):42-52
• Cited by: 87 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In a 1990-1996 case-control study in western Germany, the authors investigated lung cancer risk due to exposure to residential radon. Confirmed lung cancer cases from hospitals and a random sample of community controls were interviewed by trained interviewers regarding different risk factors. For 1 year, alpha track detectors were placed in dwellings to measure radon gas concentrations. The evaluation included 1,449 cases and 2,297 controls recruited from the entire study area and a subsample of 365 cases and 595 controls from radon-prone areas of the basic study region. Rate ratios were estimated by using conditional logistic regression adjusted for smoking and for asbestos exposure. In the entire study area, no rate ratios different from 1.0 were found; in the radon-prone areas, the adjusted rate ratios for exposure in the present dwelling were 1.59 (95% confidence interval (CI): 1.08, 2.27), 1.93 (95% CI: 1.19, 3.13), and 1.93 (95% CI: 0.99, 3.77) for 50-80, 80-140, and >140 Bq/m3, respectively, compared with 0-50 Bq/m3. The excess rate ratio for an increase of 100 Bq/m3 was 0.13 (-0.12 to 0.46). An analysis based on cumulative exposure produced similar results. The results provide additional evidence that residential radon is a risk factor for lung cancer, although a risk was detected in radon-prone areas only, not in the entire study area.

In plain English

This case-control study in western Germany, 1990 to 1996, examined whether radon gas in homes was linked to lung cancer. Lung cancer patients from hospitals and randomly chosen community controls were interviewed, and radon detectors were placed in their living rooms and bedrooms for one year. The analysis covered 1,449 cases and 2,297 controls overall, including 365 cases and 595 controls from radon-prone areas. Results were adjusted for smoking and for ever versus never occupational asbestos exposure. No increased risk was found across the whole study area. In the radon-prone areas, adjusted rate ratios were 1.59 (95 percent CI 1.08 to 2.27), 1.93 (1.19 to 3.13) and 1.93 (0.99 to 3.77) for 50 to 80, 80 to 140 and above 140 Bq/m3, compared with 0 to 50 Bq/m3. The trend per 100 Bq/m3 was not statistically significant. Occupational asbestos exposure, found only in men, had a smoking-adjusted rate ratio of 1.7 (95 percent CI 1.4 to 2.0). Adjusting for it did not change the radon results. The authors concluded that their results suggest residential radon contributes to lung cancer risk in the general population.

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: Case-control study with hospital-based cases and population-based controls, analysed by conditional logistic regression
• Who was studied: Western Germany. Lung cancer cases were recruited from nine hospitals from October 1990 to October 1995, and population controls were interviewed from October 1990 to March 1996. The analysis included 1,449 cases and 2,297 controls from the entire study area, among them a subsample of 365 cases and 595 controls from radon-prone matching areas.
• Exposure: Residential radon, measured with 1-year solid-state nuclear track detectors in the living room and bedroom of current and previous homes. Occupational asbestos exposure (ever/never) was considered only as a possible confounder.
• Main results:
  • In the entire study area, no increased lung cancer risk was found for radon in the last dwelling.
  • In the radon-prone matching areas, the adjusted rate ratio for 50 to 80 Bq/m3 in the last dwelling was 1.59 (95% CI 1.08, 2.27), compared with 0 to 50 Bq/m3.
  • In the radon-prone matching areas, the adjusted rate ratio for 80 to 140 Bq/m3 was 1.93 (95% CI 1.19, 3.13).
  • In the radon-prone matching areas, the adjusted rate ratio for more than 140 Bq/m3 was 1.93 (95% CI 0.99, 3.77). This interval includes 1.
  • In the radon-prone matching areas, the adjusted excess rate ratio was 0.13 per 100 Bq/m3 increase. This trend was not statistically significant at the 5 percent level.
  • In the radon-prone matching areas, adjusted rate ratios for cumulative exposure 5 to 15 years before interview were 1.67 (95% CI 1.04, 2.69), 1.55 (95% CI 0.83, 2.90) and 2.60 (95% CI 1.38, 4.93) for 20 to 40, 40 to 60 and more than 60 Bq/m3 a per year, compared with 0 to 20.
  • For small-cell carcinoma in the radon-prone matching areas, the highest radon category (more than 140 Bq/m3) was associated with a 3.4-fold (95% CI 1.3, 8.7) increased risk.
  • Occupational asbestos exposure was found only in men: 30.6 percent of male cases and 19.8 percent of male controls.
  • For occupational asbestos exposure in men, the smoking-adjusted rate ratio for lung cancer was 1.7 (95% CI 1.4, 2.0).
  • Adjusting for occupational asbestos exposure did not change the radon risk estimates.
• The authors' conclusion: The authors concluded that the study found no radon risk in the entire study region but a radon risk in the radon-prone areas. They wrote that these results, being within the range of other case-control studies and extrapolations from miners, suggest that residential radon contributes in a relevant manner to lung cancer risk in the general population.
• Limitations the authors state:
  • Response rates among controls were low: 38 percent in the entire study area and 46 percent in the radon-prone areas.
  • Nonexposed urban controls were underrepresented, which the authors said may have biased results toward no effect in the entire study region.
  • An additional 37 percent of interviewed cases were left out of the analysis because their radon measurements were missing or incomplete.
  • Cases came from hospitals because Germany had no overall cancer registry, and how representative the cases were could not be measured.
  • Measurement error combined with a small range of radon concentrations led to exposure misclassification.

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: Case-Control Study, Lung Cancer, rate ratio, Asbestos Exposure, confidence interval, Cumulative Exposure.

Related studies

• Increased lung cancer risk due to residential radon in a pooled and extended analysis of studies in Germany — H.E. Wichmann, A.S. Rosario, et al. (2005)
• Residential radon and risk of lung cancer in Eastern Germany — M. Kreuzer, J. Heinrich, et al. (2003)
• Indoor radon levels in urban Hyderabad area, Andhra Pradesh, India — M. Sreenath Reddy, P. Yadagiri Reddy, et al. (2008)
• Residential radon exposure and lung cancer--an epidemiological study of Norwegian municipalities — K. Magnus, A. Engeland, et al. (1994)
• 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)
• Occupational lung cancer risk for men in Germany: results from a pooled case-control study — I. Brüske-Hohlfeld, M. Möhner, et al. (2000)

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