Risk factors for lung cancer in Iowa women: implications for prevention

Our plain-English summary of Risk factors for lung cancer in Iowa women: implications for prevention, by J.S. Neuberger, J.D. Mahnken, M.S. Mayo, et al (Cancer Detection and Prevention, 2006).

The study

• Authors: J.S. Neuberger, J.D. Mahnken, M.S. Mayo, R.W. Field
• Journal: Cancer Detection and Prevention
• Published: 2006;30(2):158-67
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Multiple risk factors possibly associated with lung cancer were examined as part of a large-scale residential radon case-control study conducted in Iowa between 1994 and 1997. We were particularly interested in stratifying risk factors by smoking status. Relatively little risk factor information is available for Midwestern rural women.

Methods: Four hundred thirteen female lung cancer cases and 614 controls aged 40-84, who were residents of their current home for at least 20 years, were included. Risk factors examined included cigarette smoking, passive smoking, occupation, chemical exposure, previous lung disease, family history of cancer, and urban residence. Multiple logistic regression analysis was conducted after adjusting for age, education, and cumulative radon exposure.

Results: As expected, active cigarette smoking was the major risk factor for lung cancer. While cessation of smoking was significantly associated with a reduced risk for lung cancer, the risk remained significantly elevated for 25 years. Among all cases, asbestos exposure was a significant risk. Among ex-smokers, pack-year history predominated as the major risk. Among never smokers, a family history of kidney or bladder cancer were significant risk factors (OR=7.34, 95% CI=1.91-28.18; and OR=5.02, 95% CI=1.64-15.39, respectively), as was a history of previous lung disease (OR=2.28, 95% CI=1.24-4.18) and asbestos exposure. No statistically significant increase in lung cancer risk was found for occupation or urban residence.

Conclusions: Smoking prevention activities are urgently needed in rural areas of the United States. Relatives of individuals with smoking-related cancers are potentially at increased risk. Genetic risk factors should be more fully investigated in never smokers.

In plain English

This case-control study, part of the Iowa Radon Lung Cancer Study, compared 413 Iowa women aged 40 to 84 with lung cancer and 614 without. All had lived in their current home for at least 20 years. Questionnaires covered smoking, jobs, asbestos, prior lung disease and family cancer history. Ten cases (2.4%) and 12 controls (2.0%) reported asbestos exposure, and the unadjusted odds ratio of 1.24 was not statistically significant. After adjustment for age, education and radon, asbestos exposure was associated with lung cancer in all women (odds ratio 3.39, 95% CI 1.18 to 9.75). Among never smokers in living-case analyses (37 cases), asbestos was significant only once family history was limited to first-degree relatives (odds ratio 4.38, 95% CI 1.10 to 17.45). It was also significant when controls with other cancers were removed as well (odds ratio 5.17, 95% CI 1.20 to 22.36). Current smoking was the largest risk factor, and occupation was not significant. The authors noted a 52% control response rate and few never smokers. They concluded that rural states urgently need smoking-reduction efforts, and that prevention education should mention asbestos and family cancer history.

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: population-based case-control study, analyzing risk factors other than radon within the Iowa Radon Lung Cancer Study
• Who was studied: 413 women with newly diagnosed lung cancer (cases identified May 1, 1993 to October 30, 1996 by the Iowa Cancer Registry) and 614 women without lung cancer (controls), aged 40-84, who had lived in their current Iowa home for at least 20 consecutive years
• Exposure: Self-reported asbestos exposure, assessed by classifying occupations as exposed or not exposed to asbestos or other selected workplace carcinogens; fiber type not specified. Smoking, passive smoking, family cancer history, prior lung disease, urban residence and radon were also studied
• Main results:
  • Unadjusted (total population): asbestos exposure was reported by 10 of 413 cases (2.4%) and 12 of 614 controls (2.0%); OR 1.24, 95% CI 0.53-2.91, not statistically significant
  • Adjusted for radon, education and age (all subjects): asbestos exposure OR 3.39, 95% CI 1.18-9.75
  • Never smokers, model with live cases (37) and all controls, with family history restricted to first-degree relatives: asbestos exposure OR 4.38, 95% CI 1.10-17.45. Asbestos had not appeared among the significant results for never smokers in the earlier live-case model (Table 3)
  • Never smokers, same first-degree-relative live-case model but with controls who had other cancers removed (37 cases, 359 controls): asbestos exposure OR 5.17, 95% CI 1.20-22.36
  • All subjects, adjusted: current smoking OR 13.92, 95% CI 7.40-26.18, followed by ex-smoking
  • All subjects, adjusted: each year since quitting smoking (up to 25 years) was associated with reduced risk, OR 0.92, 95% CI 0.88-0.96
  • Never smokers, adjusted (56 cases): family history of kidney cancer OR 7.34, 95% CI 1.91-28.18
  • Never smokers, adjusted: family history of bladder cancer OR 5.02, 95% CI 1.64-15.39; any prior lung disease OR 2.28, 95% CI 1.24-4.18
  • Occupation was not found to be a risk factor, while asbestos exposure was
• The authors' conclusion: The authors concluded that urgent efforts are needed in Iowa and other rural states to reduce smoking. They also concluded that lung cancer education and prevention should include information on the potential link between lung cancer and both asbestos exposure and a family history of cancer.
• Limitations the authors state:
  • The response rate among controls was 52%
  • Sample sizes for never smokers and ex-smokers were likely too small to fully examine risk factors in those groups
  • Sample sizes were limited for some analyses, and information from proxy interviews may have been of lower quality
  • Family history of cancer may be affected by recall bias
  • Information on the timing of passive smoking exposure was unreliable, so the second-hand smoke data may not be valid
  • Some women classified as never smokers could have smoked at a low level
  • The results are best generalized to midwestern women who had lived at least 20 years in their current home

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, Case-Control Study, Asbestos Exposure.

Related studies

• Occupational risk factors for lung cancer in women: results of a case-control study in Germany — I. Jahn, W. Ahrens, et al. (1999)
• Asbestos exposure, manganese superoxide dismutase (MnSOD) genotype, and lung cancer risk — L.I. Wang, D. Neuberg, et al. (2004)
• Chronic obstructive lung diseases and risk of non-small cell lung cancer in women — A.G. Schwartz, M.L. Cote, et al. (2009)
• Past and current asbestos exposure and future mesothelioma risks in Britain: The Inhaled Particles Study (TIPS) — C. Gilham, C. Rake, et al. (2018)
• 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)

Browse return to medical research.