The joint effect of asbestos exposure, tobacco smoking and alcohol drinking on laryngeal cancer risk: evidence from the French population-based case-control study, ICARE

Our plain-English summary of The joint effect of asbestos exposure, tobacco smoking and alcohol drinking on laryngeal cancer risk: evidence from the French population-based case-control study, ICARE, by G. Menvielle, A. Fayossé, L. Radoï, et al (Occupational and Environmental Medicine, 2016).

The study

• Authors: G. Menvielle, A. Fayossé, L. Radoï, F. Guida, M. Sanchez, M. Carton, D. Cyr, A. Schmaus, S. Cénée, J. Fevotte, P. Delafosse, I. Stücker, D. Luce, ICARE study group
• Journal: Occupational and Environmental Medicine
• Published: 2016;73(1):28-33
• Cited by: 24 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: The objective of the study was to investigate the joint effect of occupational exposure to asbestos, and tobacco and alcohol consumption, on the risk of laryngeal cancer among men.

Methods: We used data from a large population-based case-control study conducted in France. We estimated two-way and three-way interactions between asbestos exposure (never vs ever exposed), tobacco consumption (<20 vs. ≥20 pack-years) and alcohol consumption (<5 vs. ≥5 drinks per day). The interaction on an additive scale was assessed by estimating the relative excess risk due to interaction (RERI) and the attributable proportion due to interaction, and the interaction on a multiplicative scale was assessed by estimating the multiplicative interaction parameter (ψ). Multiplicative interactions were also assessed using fractional polynomials for alcohol drinking, tobacco smoking and asbestos exposure.

Results: When compared with light-to-moderate smokers and drinkers never exposed to asbestos, the increase in laryngeal cancer risk was smallest among light-to-moderate drinkers and smokers exposed to asbestos (OR=2.23 (1.08 to 4.60)), and highest among heavy smokers and drinkers ever exposed to asbestos (OR=69.39 (35.54 to 135.5)). We found an additive joint effect between asbestos exposure and alcohol consumption (RERI=4.75 (-4.29 to 11.12)), whereas we observed a more than additive joint effect between asbestos exposure and tobacco consumption (RERI=8.50 (0.71 to 23.81)), as well as between asbestos exposure, and tobacco and alcohol consumption (RERI=26.57 (11.52 to 67.88)). However, our results did not suggest any interaction on a multiplicative scale.

Conclusions: Our results suggest that asbestos exposure, in combination with tobacco and alcohol exposure, accounted for a substantial number of laryngeal cancer cases. Our findings therefore highlight the need for prevention in activities, such as construction work, where exposure to asbestos-containing materials remains.

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In plain English

This French population-based case-control study (ICARE, 2001 to 2007) examined the joint effect of occupational asbestos exposure, smoking and drinking on laryngeal cancer in men. It analysed 448 men with squamous cell laryngeal cancer and 2686 male controls, estimating asbestos exposure from job histories. Cases were more often ever exposed to asbestos (73%) than controls (58%). Compared with never-exposed men who smoked under 20 pack-years and drank under 5 drinks a day, the odds ratio was 2.23 (1.08 to 4.60) for similar men exposed to asbestos and 69.39 (35.54 to 135.5) for exposed heavy smokers and heavy drinkers. Among light-to-moderate drinkers, the combined effect of asbestos and smoking was greater than the sum of their separate effects. Among light-to-moderate smokers, the joint asbestos and alcohol effect did not differ significantly from that sum. No multiplicative-scale interaction was statistically significant. The authors attributed 33% of all laryngeal cancer cases in the population to combined exposure to all three. They suggested tobacco was the key factor explaining the increased risk among male drinkers and smokers exposed to asbestos.

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 (multicentre ICARE study), analysed for two-way and three-way interactions on additive and multiplicative scales
• Who was studied: Men in 10 French départements covered by cancer registries, 2001 to 2007. The study included 473 men with squamous cell laryngeal cancer; after excluding men with missing data, 448 cases and 2686 population controls selected by random digit dialling were analysed.
• Exposure: Occupational asbestos exposure (fiber type not specified), estimated from lifetime job history with a French job-exposure matrix. It was expressed as cumulative exposure in fibres/mL year, duration and maximal probability, and as ever versus never exposed for the interaction analyses. Tobacco smoking was measured in pack-years (cut at 20) and alcohol drinking in drinks per day (cut at 5).
• Main results:
  • Ever exposure to asbestos: 73% of cases versus 58% of controls.
  • Men with the highest cumulative asbestos exposure, compared with never-exposed men: OR 1.81 (95% CI 1.32 to 2.48), adjusted for smoking and drinking.
  • Light-to-moderate smokers and drinkers exposed to asbestos (30 cases, 896 controls), compared with never-exposed light-to-moderate smokers and drinkers (10 cases, 684 controls): OR 2.23 (1.08 to 4.60). This was the smallest increase among the profiles.
  • Heavy smokers and heavy drinkers ever exposed to asbestos (150 cases, 159 controls), compared with the same reference group: OR 69.39 (35.54 to 135.5). This was the highest increase.
  • The two-way interaction measures were computed among men not exposed to the third factor. Among light-to-moderate drinkers, the joint effect of asbestos exposure and tobacco consumption was more than additive: RERI 8.50 (0.71 to 23.81).
  • Among light-to-moderate smokers, the joint effect of asbestos exposure and alcohol consumption did not depart significantly from additivity: RERI 4.75 (minus 4.29 to 11.12).
  • Among men never exposed to asbestos, the joint effect of tobacco and alcohol was more than additive: RERI 26.57 (11.52 to 67.88).
  • The three-way joint effect of asbestos, tobacco and alcohol was greater than the sum of their independent effects: RERI 48.88 (30.42 to 106.0).
  • No interaction was statistically significant on a multiplicative scale. All confidence intervals of the multiplicative interaction parameter included 1.
  • Among heavy drinkers and smokers exposed to asbestos, 70% of laryngeal cancer cases were attributable to the interaction between asbestos, tobacco and alcohol.
  • Overall, 33% of all laryngeal cancer cases in the population were attributable to the combined exposure to asbestos, tobacco and alcohol.
• The authors' conclusion: The authors concluded that asbestos exposure, in combination with tobacco and alcohol exposure, accounted for a substantial number of laryngeal cancer cases. They suggested that tobacco consumption was the key factor explaining the increased risk among male drinkers and smokers exposed to asbestos.
• Limitations the authors state:
  • Recall bias is a known weakness of case-control studies.
  • Self-reported smoking and drinking may have underestimated true consumption, and differential reporting between cases and controls cannot be excluded.
  • Using dichotomous (two-category) variables for the additive interaction measures meant the three factors could not be accounted for in detail.
  • The reference group included light smokers and men drinking less than 5 drinks per day.
  • The sensitivity analyses rested on very small numbers of cases in the reference categories.
  • Misclassification of exposure cannot be totally ruled out. Non-differential misclassification from the job-exposure matrix could bias results toward the null.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Throat and laryngeal cancer.

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Laryngeal Cancer, Case-Control Study, Occupational Exposure, Asbestos-Containing Material (ACM).

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