Body Mass Index and Risk of Lung Cancer Among Never, Former, and Current Smokers

Smith, Lawrence H.; Brinton, Louise A.; Spitz, Margaret R.; Lam, Tram Kim; Park, Yikyung; Hollenbeck, Albert R.; Freedman, Neal D.; Gierach, Gretchen L.

doi:10.1093/jnci/djs179

Cited by 105 publications

(123 citation statements)

References 40 publications

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“…3,6,8,16 One of these studies, by contrast with the rest also reported that obese men had an increased risk of adenocarcinoma, particularly among never and former smokers. 3 Most of these studies, including ours, were limited in that there were too few cases of some histologic subtypes, especially among never smokers, to stratify analyses by smoking.…”

Section: Epidemiologymentioning

confidence: 96%

“…16 Using data from a large prospective study that included 9,437 lung cancer cases (415 cases among never smokers), the authors reported that BMI was more strongly associated with reductions in lung cancer risk among obese women compared with obese men. Based on this finding and the recognized strong correlations between obesity and higher levels of estrogens, 50 the authors suggest that estrogens play a role in these associations.…”

Section: True Etiological Effectmentioning

confidence: 99%

“…Third, an etiologic explanation, namely through carcinogenic DNA adducts 6 or effects of estrogens. 16 In any case, the interplay between BMI, smoking, and lung cancer remains uncertain.In the context of a large population-based case-control study on the environmental etiology of lung cancer, data on sociodemographic, anthropometric, and lifestyle factors were collected. A Comprehensive Smoking Index (CSI), summarizing the most relevant aspects of an individual's smoking history (i.e., smoking status, intensity, duration, and time since cessation), was adapted for this study.…”

mentioning

confidence: 99%

“…Third, an etiologic explanation, namely through carcinogenic DNA adducts 6 or effects of estrogens. 16 In any case, the interplay between BMI, smoking, and lung cancer remains uncertain.…”

mentioning

confidence: 99%

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Body mass index, lifetime smoking intensity and lung cancer risk

El‐Zein

Parent

Nicolau

et al. 2013

Intl Journal of Cancer

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There is as yet no generally accepted explanation for the common finding that low body mass index (BMI) is associated with an increased risk of lung cancer. We investigated this association in a Canadian population-based case-control study (1996)(1997)(1998)(1999)(2000)(2001)(2002) with a particular view to assessing the hypothesis that the observed association was due to residual confounding by smoking. Analyses were based on 1,076 cases and 1,439 controls who provided their height at enrollment and their weight at two points in time, at age 20 and 2 years before enrollment. BMI, in kg/m 2 , was classified into underweight (<18.5), normal (18.5-24.9), overweight (25.0-29.9), and obese (30). Smoking history was synthesized into a comprehensive smoking index (CSI) that integrated duration, intensity and time since quitting. Odds ratios (ORs) and 95% confidence intervals (CIs) for BMI-lung cancer associations were estimated, adjusting for CSI as well as several sociodemographic, lifestyle and occupational factors. The normal BMI category was used as the reference. Among those who were underweight at age 20, there was a lower risk of lung cancer (OR 5 0.69, 95% CI: 0.50-0.95). Conversely, lung cancer risk was increased among those who were underweight 2 years before enrollment (OR 5 2.30, 95% CI: 1.30-4.10). The results were almost identical when stratifying analyses based on smoking history into never/lighter and heavier smokers. The inverse association between recent BMI and lung cancer is unlikely to be largely attributable to residual confounding by smoking. Reverse causality or a true relationship between BMI and lung cancer remain plausible.Elevated body mass index (BMI) has been associated with an increased risk of several cancers, including esophageal, pancreatic, colorectal, endometrial, postmenopausal breast, and prostate cancers.1 By contrast, BMI appears to be inversely related to lung cancer risk.2-16 However, the robustness and meaning of this ostensible inverse association has been challenged in some studies by the finding that such an inverse association was not present among nonsmokers. 4,9,10,12 Smoking is both a powerful risk factor for lung cancer, 17 and is also inversely associated with body weight. 18,19 Several explanations have been hypothesized regarding the observed inverse BMI-lung cancer association. First, a methodological argument, according to which residual confounding by smoking accounted for observing an inverse, or disguising a true positive, BMI-lung cancer relation. Second, reverse causality due to pre-clinical effects of lung cancer, especially for studies in which weight was documented shortly before cancer diagnosis. Third, an etiologic explanation, namely through carcinogenic DNA adducts 6 or effects of estrogens. 16 In any case, the interplay between BMI, smoking, and lung cancer remains uncertain.In the context of a large population-based case-control study on the environmental etiology of lung cancer, data on sociodemographic, anthropometric, and lifestyle factors were c...

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Section: Epidemiologymentioning

confidence: 96%

Section: True Etiological Effectmentioning

confidence: 99%

mentioning

confidence: 99%

“…Third, an etiologic explanation, namely through carcinogenic DNA adducts 6 or effects of estrogens. 16 In any case, the interplay between BMI, smoking, and lung cancer remains uncertain.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Body mass index, lifetime smoking intensity and lung cancer risk

El‐Zein

Parent

Nicolau

et al. 2013

Intl Journal of Cancer

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“…As smoking status is the most common confounder in the study of the association between BMI and lung cancer risk, we noticed that the sample size was reduced a lot after focusing on nonsmokers in most original studies, in such case the error could not be avoided. It is a good advice to take a more comprehensive approach to represent life time smoking behavior in the future study as suggested by Dr. Mariam El-Zein.Recently, we noticed that Smith et al 4 also found an inverse association between BMI and lung cancer risk in smokers in a large cohort study, along with Tarnaud's findings, 5 the inverse relationship in smokers is certain and confirmable to some extent, so our extrapolated suggestion that ''smokers should improve their nutritional status and maintain a suitable body weight'' is tenable and apprehensible. However, the relationship between BMI and lung cancer risk in nonsmokers is still ambiguous, especially in males, we speculate that even such relationship exists, the extent is relatively weak, and obviously there is no evidence that obesity can increase lung cancer risk like some other types of cancer in nonsmokers.…”

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confidence: 65%

Authors' reply to comments on a recent meta‐analysis: Obesity and lung cancer

Yang

Jiao

2012

Intl Journal of Cancer

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We thank Dr. Mariam El-Zein and coworkers for their interest in our article. After reviewing the comments and checking our raw data and original article carefully, we are pleased to reply and explain their questions one by one. HeterogeneityIn our meta-analysis, significant heterogeneity was indeed observed in almost all the study results, even, stratified analyses by study design, smoking status, area, and other confounders could not eliminate the heterogeneity. As Dr. Mariam El-Zein pointed out, a lot of factors could contribute to the heterogeneity such as distinctive characteristics of individual studies, variability between studies and also a large number of studies, so it is sometimes difficult to find the accurate source of heterogeneity. However, the inverse association kept unchanged with stratification by the confounders. What is more, the pooled RR did not change much (figure not shown) when the sensitivity analysis was conducted. In addition, when a new meta-analysis was carried out after removing the studies that caused significant heterogeneity (refer to the Refs. 7, 9, 10, 13, 16, 18, 26, 28, 36, 41, and 42 in the original article), the results showed that the pooled RR was 0.78 (95%CI: 0.75-0.81, I 2 ¼ 0.0, p ¼ 0.697), which stayed almost the same with the original one (figure not shown). All of the evidence above indicated that the heterogeneity exerted little influence to our meta-analysis results. Methodological Quality of Original StudiesWe acknowledge that we did not include a formal evaluation table of study quality in our meta-analysis, because it is quite common in the similar meta-analysis.1,2 Although there are many appraisal tools to evaluate the methodological quality of studies; however, for the observational studies, there are still not well-established standard assessment methods like JADAD or JUNI for random controlled trials.3 As all the studies included in our study were in accordance with our study selection criteria, we did not exclude the ''smaller'' studies, which was a relative concept. It is sometimes incompatible to choose a comprehensive analysis or to get an improved result after excluding some ''smaller'' studies. Confounding by SmokingAs pointed by Dr. Mariam El-Zein, the relationship between BMI and lung cancer risk in nonsmokers is always the central issue that controversy focus on. In our meta-analysis, the results showed that the inverse association existed in female nonsmokers, whereas it became statically nonsignificant in male nonsmokers. As smoking status is the most common confounder in the study of the association between BMI and lung cancer risk, we noticed that the sample size was reduced a lot after focusing on nonsmokers in most original studies, in such case the error could not be avoided. It is a good advice to take a more comprehensive approach to represent life time smoking behavior in the future study as suggested by Dr. Mariam El-Zein.Recently, we noticed that Smith et al. 4 also found an inverse association between BMI and lung cancer risk in sm...

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Lifestyle associated factors and risk of urinary bladder cancer: A prospective cohort study from Norway

et al. 2020

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A number of lifestyle associated factors, such as high body mass index (BMI), low physical activity, and related metabolic disorders, are associated with increased risk of cancer at several sites. For urinary bladder cancer (BC), such studies show inconsistent results, which could result from inadequate adjustment for smoking and occupational exposure. In the population-based Janus Cohort (n = 292 851), we investigated the independent and combined impact of BMI, physical activity, blood pressure, and blood lipids on the risk of BC, by thorough adjustment for smoking and potential occupational exposure. We used cox proportional hazard regression to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) for the associations between the lifestyle associated factors and BC risk. The associations observed were dependent on smoking status and gender. Among men, diastolic blood pressure (DBP) (HR 1.07, 95% CI 1.02-1.12) and systolic blood pressure (SBP) (HR 1.04, 95% CI 1.01-1.07) were positively associated with BC risk. Stratification by smoking status revealed a positive association between DBP and BC risk in never smokers (HR 1.14, 95% CI 1.00-1.30), while no association was seen for current and former smokers. A risk score, integrating information across the lifestyle factors was positively associated with BC risk in men (p trend = 0.043). In women, physical activity was associated with a decreased BC risk, but only among never smokers (HR 0.65, 95% CI 0.45-0.94). In conclusion, relations between lifestyle associated factors and BC risk were most evident in never smokers, suggesting that smoking dominates the relation in current smokers.

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Body Mass Index and Risk of Lung Cancer Among Never, Former, and Current Smokers

Cited by 105 publications

References 40 publications

Body mass index, lifetime smoking intensity and lung cancer risk

Body mass index, lifetime smoking intensity and lung cancer risk

Authors' reply to comments on a recent meta‐analysis: Obesity and lung cancer

Lifestyle associated factors and risk of urinary bladder cancer: A prospective cohort study from Norway

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