Smoking, occupational risk factors, and bronchial tumor location: a possible impact for lung cancer computed tomography scan screening

Our plain-English summary of Smoking, occupational risk factors, and bronchial tumor location: a possible impact for lung cancer computed tomography scan screening, by M. Gonzalez, J.M. Vignaud, C. Clement-Duchene, et al (Journal of Thoracic Oncology, 2012).

The study

• Authors: M. Gonzalez, J.M. Vignaud, C. Clement-Duchene, A. Luc, P. Wild, O. Bertrand, L. Thiberville, Y. Martinet, J. Benichou, C. Paris
• Journal: Journal of Thoracic Oncology
• Published: 2012;7(1):128-36
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: The aim of this study was to describe associations between lung tumor location and smoking as well as selected occupational exposures. In the context of lung cancer screening by computed tomography scan, tumor location may have an interest. Computed tomography scan is known to better detect more peripheral tumors.

Methods: Lung cancer cases diagnosed in two French University hospitals between 1997 and 2009 were included. Tumors visible on white-light bronchoscopy were defined as central. Occupational exposures were assessed by the same expert. Data were analyzed by case-case comparisons using unconditional logistic regressions.

Results: A total of 1701 cases were included, comprising mainly men (86.3%), current smokers (52.8%), or former smokers (42.8%). Main histological subtypes of cancer were adenocarcinomas (33.8%) and squamous cell carcinomas (32.6%). The tumor location was found to be central in 61% of cases, and never smokers and women had more often peripheral tumors. Exposure to asbestos was significantly associated with central location with dose-response relationship (odds ratio [OR] for peripheral tumors = 0.45, 95% confidence interval [CI] 0.29-0.70) for the highest level of exposure. Exposure to silica dust was significantly associated with peripheral tumor (OR for peripheral tumors = 3.28, 95%CI 1.50-7.17) for the highest level of exposure. Exposure to welding fumes was associated with central location (OR for peripheral tumors = 0.51, 95% CI 0.26-0.96) for the first level of exposure).

Conclusions: Smoking characteristics and occupational exposures have to be considered to define more accurately high-risk populations suitable for lung cancer screening or early detection programs.

In plain English

This study asked whether smoking and workplace exposures were linked to where lung cancers grew in the lungs. The authors studied 1,701 people diagnosed with lung cancer at two French university hospitals (Rouen, 1997 to 2005; Nancy, 2001 to 2009). Of these, 86.3% were men. Tumors visible on standard bronchoscopy were called central, and the rest were called peripheral. An occupational physician scored each person's past workplace exposures, including asbestos. Because everyone studied had lung cancer, the results describe tumor location, not the risk of getting cancer. Overall, 61% of tumors were central. In the group with the highest cumulative asbestos exposure (135 people), tumors were less often peripheral: adjusted odds ratio 0.45 (95% CI 0.29 to 0.70), with a statistically significant dose-response trend. Lower asbestos levels showed no significant difference. The highest silica exposure group (29 people) had more peripheral tumors (adjusted odds ratio 3.28, 95% CI 1.50 to 7.17). The authors concluded that smoking and occupational exposures may need to be considered when defining high-risk groups for CT lung cancer screening.

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-case study of incident lung cancer cases (central versus peripheral tumor location), analyzed with unconditional logistic regression
• Who was studied: 1701 incident lung cancer cases diagnosed at Rouen University Hospital (January 1, 1997 to December 31, 2005) and Nancy University Hospital (January 1, 2001 to June 2009), France; 1468 men (86.3%); 75 never smokers (4.4%)
• Exposure: Occupational exposure to lung carcinogens: asbestos (fiber type not specified), chromium, arsenic, cadmium, silica, nickel, welding fumes, diesel exhausts, PAHs and radon. Each was scored as a cumulative exposure index by an occupational physician; asbestos exposure was found in 571 patients (33.6%). Smoking history was also recorded.
• Main results:
  • Tumor location was central in 61% of the 1701 cases (1037 central, 664 peripheral)
  • Unadjusted: 65.0% of asbestos-exposed patients had central tumors versus 58.9% of non-exposed patients
  • Adjusted for age, gender and smoking status, the highest cumulative asbestos exposure group (135 patients) had an OR for peripheral location of 0.45 (95% CI 0.29 to 0.70); the low (1.01, 0.75 to 1.35) and moderate (0.91, 0.66 to 1.26) groups were not significant; trend test p = 0.002
  • After also adjusting for histological type, the highest asbestos exposure group still had an OR for peripheral location of 0.48 (95% CI 0.31 to 0.76)
  • The highest silica exposure group (29 patients) had an adjusted OR for peripheral location of 3.28 (95% CI 1.50 to 7.17)
  • The low welding fumes exposure group had an adjusted OR for peripheral location of 0.51 (95% CI 0.26 to 0.96), with no significant trend across exposure levels
  • Never smokers had more often peripheral tumors than current smokers (unadjusted OR 1.74, 95% CI 1.08 to 2.79); smoking status became nonsignificant once histology was added to the model
  • Interactions between smoking status and occupational exposures were not significant
  • The odds ratios describe the distribution of tumor location among people who already had lung cancer, not the effect of exposure on getting the disease
• The authors' conclusion: The authors concluded that smoking characteristics and occupational exposures appear to affect whether lung cancer is central or peripheral, and that this may need to be considered in defining high-risk populations for CT screening. They suggested the benefit of CT screening may be lower in heavy smokers or asbestos-exposed people.
• Limitations the authors state:
  • Patients came from only two hospitals, in areas with former heavy industries and high rates of occupational exposure
  • Most patients were diagnosed because of symptoms rather than screening, and the number detected by chest X-ray or CT screening is not known
  • The subjects cannot be considered representative of all lung cancer cases
  • Comparison with other studies is difficult because definitions of central and peripheral location differ between authors

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer, Occupational Exposure, Low-Dose CT Screening, Bronchoscopy, Histological Subtype, Adenocarcinoma, Squamous Cell Carcinoma, Dose-response relationship.

Related studies

• Smoking status, occupational asbestos exposure and bronchial location of lung cancer — C. Paris, J. Benichou, et al. (2003)
• Psychological impact of computed tomography screening for lung cancer and occupational pulmonary disease among asbestos-exposed workers — T. Vierikko, S. Kivistö, et al. (2009)
• Occupational and nonoccupational factors associated with high grade bronchial pre-invasive lesions — C. Paris, J. Benichou, et al. (2003)
• Association of cigarette smoking and asbestos exposure with location and histology of lung cancer — B.W. Lee, J.C. Wain, et al. (1998)
• Lung function not affected by asbestos exposure in workers with normal Computed Tomography scan — C. Schikowsky, M.K. Felten, et al. (2017)
• 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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