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Body mass index and risk of lung cancer among never, former, and current smokers.

Abstract

BACKGROUND

Although obesity has been directly linked to the development of many cancers, many epidemiological studies have found that body mass index (BMI)--a surrogate marker of obesity--is inversely associated with the risk of lung cancer. These studies are difficult to interpret because of potential confounding by cigarette smoking, a major risk factor for lung cancer that is associated with lower BMI.

METHODS

We prospectively examined the association between BMI and the risk of lung cancer among 448 732 men and women aged 50-71 years who were recruited during 1995-1996 for the National Institutes of Health-AARP Diet and Health Study. BMI was calculated based on the participant's self-reported height and weight on the baseline questionnaire. We identified 9437 incident lung carcinomas (including 415 in never smokers) during a mean follow-up of 9.7 years through 2006. Multivariable Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) with adjustment for lung cancer risk factors, including smoking status. To address potential bias due to preexisting undiagnosed disease, we excluded potentially unhealthy participants in sensitivity analyses. All statistical tests were two-sided.

RESULTS

The crude incidence rate of lung cancer over the study follow-up period was 233 per 100 000 person-years among men and 192 per 100 000 person-years among women. BMI was inversely associated with the risk of lung cancer among both men and women (BMI ≥35 vs 22.5-24.99 kg/m(2): HR = 0.81, 95% CI = 0.70 to 0.94 and HR = 0.73, 95% CI = 0.61 to 0.87, respectively). The inverse association was restricted to current and former smokers and was stronger after adjustment for smoking. Among smokers, the inverse association persisted even after finely stratifying on smoking status, time since quitting smoking, and number of cigarettes smoked per day. Sensitivity analyses did not support the possibility that the inverse association was due to prevalent undiagnosed disease.

CONCLUSIONS

Our results suggest that a higher BMI is associated with a reduced risk of lung cancer in current and former smokers. Our inability to attribute the inverse association between BMI and the risk of lung cancer to residual confounding by smoking or to bias suggests the need for considering other explanations.

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  • Authors+Show Affiliations

    ,

    Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20852-7234, USA.

    , , , , , ,

    Source

    Journal of the National Cancer Institute 104:10 2012 May 16 pg 778-89

    MeSH

    Aged
    Body Mass Index
    Female
    Humans
    Incidence
    Lung Neoplasms
    Male
    Middle Aged
    Multivariate Analysis
    Proportional Hazards Models
    Prospective Studies
    Risk Assessment
    Risk Factors
    Smoking
    Surveys and Questionnaires
    United States

    Pub Type(s)

    Journal Article
    Research Support, N.I.H., Intramural

    Language

    eng

    PubMed ID

    22457475

    Citation

    Smith, Llewellyn, et al. "Body Mass Index and Risk of Lung Cancer Among Never, Former, and Current Smokers." Journal of the National Cancer Institute, vol. 104, no. 10, 2012, pp. 778-89.
    Smith L, Brinton LA, Spitz MR, et al. Body mass index and risk of lung cancer among never, former, and current smokers. J Natl Cancer Inst. 2012;104(10):778-89.
    Smith, L., Brinton, L. A., Spitz, M. R., Lam, T. K., Park, Y., Hollenbeck, A. R., ... Gierach, G. L. (2012). Body mass index and risk of lung cancer among never, former, and current smokers. Journal of the National Cancer Institute, 104(10), pp. 778-89. doi:10.1093/jnci/djs179.
    Smith L, et al. Body Mass Index and Risk of Lung Cancer Among Never, Former, and Current Smokers. J Natl Cancer Inst. 2012 May 16;104(10):778-89. PubMed PMID: 22457475.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Body mass index and risk of lung cancer among never, former, and current smokers. AU - Smith,Llewellyn, AU - Brinton,Louise A, AU - Spitz,Margaret R, AU - Lam,Tram Kim, AU - Park,Yikyung, AU - Hollenbeck,Albert R, AU - Freedman,Neal D, AU - Gierach,Gretchen L, Y1 - 2012/03/27/ PY - 2012/3/30/entrez PY - 2012/3/30/pubmed PY - 2012/7/3/medline SP - 778 EP - 89 JF - Journal of the National Cancer Institute JO - J. Natl. Cancer Inst. VL - 104 IS - 10 N2 - BACKGROUND: Although obesity has been directly linked to the development of many cancers, many epidemiological studies have found that body mass index (BMI)--a surrogate marker of obesity--is inversely associated with the risk of lung cancer. These studies are difficult to interpret because of potential confounding by cigarette smoking, a major risk factor for lung cancer that is associated with lower BMI. METHODS: We prospectively examined the association between BMI and the risk of lung cancer among 448 732 men and women aged 50-71 years who were recruited during 1995-1996 for the National Institutes of Health-AARP Diet and Health Study. BMI was calculated based on the participant's self-reported height and weight on the baseline questionnaire. We identified 9437 incident lung carcinomas (including 415 in never smokers) during a mean follow-up of 9.7 years through 2006. Multivariable Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) with adjustment for lung cancer risk factors, including smoking status. To address potential bias due to preexisting undiagnosed disease, we excluded potentially unhealthy participants in sensitivity analyses. All statistical tests were two-sided. RESULTS: The crude incidence rate of lung cancer over the study follow-up period was 233 per 100 000 person-years among men and 192 per 100 000 person-years among women. BMI was inversely associated with the risk of lung cancer among both men and women (BMI ≥35 vs 22.5-24.99 kg/m(2): HR = 0.81, 95% CI = 0.70 to 0.94 and HR = 0.73, 95% CI = 0.61 to 0.87, respectively). The inverse association was restricted to current and former smokers and was stronger after adjustment for smoking. Among smokers, the inverse association persisted even after finely stratifying on smoking status, time since quitting smoking, and number of cigarettes smoked per day. Sensitivity analyses did not support the possibility that the inverse association was due to prevalent undiagnosed disease. CONCLUSIONS: Our results suggest that a higher BMI is associated with a reduced risk of lung cancer in current and former smokers. Our inability to attribute the inverse association between BMI and the risk of lung cancer to residual confounding by smoking or to bias suggests the need for considering other explanations. SN - 1460-2105 UR - https://www.unboundmedicine.com/medline/citation/22457475/Body_mass_index_and_risk_of_lung_cancer_among_never_former_and_current_smokers_ L2 - https://academic.oup.com/jnci/article-lookup/doi/10.1093/jnci/djs179 DB - PRIME DP - Unbound Medicine ER -