Smoking status, occupational asbestos exposure and bronchial location of lung cancer

Our plain-English summary of Smoking status, occupational asbestos exposure and bronchial location of lung cancer, by C. Paris, J. Benichou, F. Saunier, et al (Lung Cancer, 2003).

The study

• Authors: C. Paris, J. Benichou, F. Saunier, J. Metayer, P. Brochard, L. Thiberville, G. Nouvet
• Journal: Lung Cancer
• Published: 2003;40(1):17-24
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The objective of this study was to determine the factors associated with central airway versus peripheral bronchial location of lung cancer. All patients diagnosed with lung cancer from 1997 through 2000 in the Respiratory Disease Department of Rouen University Hospital were prospectively interviewed about their smoking and occupational history using a standardized questionnaire. All patients underwent white-light bronchial endoscopy using a 4.5 mm flexible endoscope. Tumors were classified as central when they were accessible and visible using this technique. Out of 217 cases of lung cancer included in this study, 155 (71%) were central. Histological type of lung cancer was strongly associated with bronchial location as central location was observed in 48, 82 and 92% of Adenocarcinoma (AC), Squamous Cell (SqC), and Small Cell Carcinoma (SCC), respectively (P<0.0001). Among non asbestos-exposed patients, location varied little with smoking status, with central location frequency ranging from 74 to 80%. In contrast, lung cancer was recorded central in 41% of long-term (> or =10 years) ex-smokers, 67% of short-term (<10 years) ex-smokers and 75% of current smokers (P=0.04) among patients exposed to asbestos, suggesting an interaction between duration of smoking cessation and occupational asbestos exposure with respect to lung cancer location. These findings were confirmed after adjustment for sex, age and histologic type in multivariate analysis. These results suggest that individually-tailored multimodality screening strategies relying on various combinations of low-dose CT scan, sputum analysis and fluorescence endoscopy according to each patient's profile may be more effective than standard strategies based on a single approach for all patients.

In plain English

The authors examined whether smoking and work-related asbestos exposure were linked to where lung cancer grows in the airways. They studied all 217 patients with confirmed lung cancer hospitalized in the Respiratory Disease Department of Rouen University Hospital, France, from 1997 through 2000; 201 were men. Tumors visible with a 4.5 mm bronchoscope were called central, and the rest peripheral. An expert reviewed each work history, and 94 men had documented asbestos exposure lasting at least one year. The article does not report fiber types. Overall, 155 tumors (71%) were central. Peripheral tumors occurred in 35% of exposed and 24% of unexposed patients, a borderline result (P = 0.062). Among people who had quit smoking at least 10 years earlier, asbestos exposure was linked to peripheral location (odds ratio 5.8, 95% confidence interval 1.3 to 26.5). The link was not clear among current smokers or recent quitters, and this difference between smoking groups was not statistically significant. Adjusted analyses gave similar results. The authors concluded that smoking status and asbestos exposure both appear to influence tumor location, which needs confirming in larger studies.

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: Study of consecutive new (incident) lung cancer cases at one hospital department. Patients were interviewed with a standardized questionnaire, and tumor location was compared with smoking and occupational exposure using univariate and multivariate (logistic regression) analyses.
• Who was studied: 217 patients with histologically confirmed primary lung cancer hospitalized in the Respiratory Disease Department of Rouen University Hospital, France, from 1 January 1997 through 31 December 2000. Mean age was 59.8 years and 201 (93%) were men. There were 133 current smokers, 80 ex-smokers and 4 never-smokers.
• Exposure: Occupational asbestos exposure, judged by an expert assessment of each patient's career by one physician who was blinded to clinical and histologic data. Only documented exposure of at least 1 year counted as exposed. 94 men had documented asbestos exposure, and no women did. Fiber types, products and doses are not reported. Smoking status was also studied: current smokers, ex-smokers who quit less than 10 years earlier, and ex-smokers who quit 10 or more years earlier.
• Main results:
  • Of all 217 patients, 155 (71%) had a centrally located tumor (visible on bronchoscopy).
  • Tumor type was strongly associated with location. Small cell carcinomas were central in 92% and squamous cell carcinomas in 82%, while adenocarcinomas were peripheral in 52%.
  • Compared with current smokers, long-term ex-smokers (quit 10 or more years) had an odds ratio of 2.4 (95% CI 1.1 to 5.2) for peripheral tumor location. Short-term ex-smokers had an odds ratio of 1.4 (95% CI 0.6 to 2.9).
  • Peripheral tumors occurred in 35% of patients with documented asbestos exposure versus 24% of those without, which the authors called a borderline significant association (P = 0.062).
  • The asbestos association with peripheral location differed by smoking status. In long-term ex-smokers, peripheral tumors were found in 13 of 22 exposed versus 3 of 15 unexposed patients (OR 5.8, 95% CI 1.3 to 26.5). The odds ratio was 1.1 (95% CI 0.5 to 2.5) in current smokers and 1.4 (95% CI 0.4 to 5.3) in short-term ex-smokers.
  • This apparent interaction between asbestos exposure and smoking cessation was not statistically significant (P = 0.152, univariate test).
  • After adjustment for age, sex and histologic type, documented asbestos exposure had an odds ratio of 1.9 (95% CI 1.0 to 3.6, P = 0.069) for peripheral location. The authors described this as borderline significant.
  • In the adjusted model with interaction terms, asbestos exposure in long-term ex-smokers had an odds ratio of 5.4 (95% CI 1.1 to 25.7) for peripheral location. The interaction was again not statistically significant (P = 0.095).
  • Adenocarcinoma was equally frequent (19%) in patients with and without documented occupational asbestos exposure.
• The authors' conclusion: The authors concluded that their findings suggest lung cancer location in the bronchial tree is influenced by both smoking status and asbestos exposure, independently of age, sex and histologic type. They said that, if confirmed in larger studies, this could matter for choosing lung cancer screening methods.
• Limitations the authors state:
  • The sample size was relatively modest, and several results were only close to statistical significance and need verification in larger studies.
  • All types of tissue samples except autopsy samples were included, and adenocarcinoma was more frequent in surgical lung biopsy and metastasis biopsy samples, which may have affected the results.
  • Only four patients had never smoked, and none of them was occupationally exposed to asbestos. The joint effect of asbestos and smoking itself, as opposed to quitting smoking, could therefore not be studied.
  • Lung fibrosis seen on X-ray in asbestos-exposed patients was not taken into account.
  • Asbestos exposure was assessed from a standardized interview only, without environmental or biological samples.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Lung Cancer, Occupational History, Endoscopy, Adenocarcinoma, Squamous Cell, Carcinoma, Multivariate Analysis.

Related studies

• Smoking, occupational risk factors, and bronchial tumor location: a possible impact for lung cancer computed tomography scan screening — M. Gonzalez, J.M. Vignaud, et al. (2012)
• 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)
• The relationship between asbestosis and bronchial cancer — G.K. Sluis-Cremer (1980)
• Alcohol, smoking, and occupational factors in cancer of the larynx: a case-control study — W. Ahrens, K.H. Jöckel, et al. (1991)
• Practical steps towards the prevention of bronchial carcinoma — R. Doll (1970)

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