Jason Wong

Sc.D

National Cancer Institute

Postdoctoral Fellow

NLST (Learn more about this study)

NLST-193

Jan 25, 2016

The Interplay between Welding and Active Smoking in Relation to Risk of Lung Cancer

Industrial welders are highly exposed to fumes containing toxic levels of fine particulate matter (PM2.5), heavy metals, nanoparticles, and various gases from the combustion of base metals and fluxes. Previous studies found that boilermakers whose primary task was welding had a median workday PM2.5 exposure of 649.8 μg/m3; levels far exceeding those experienced by the general population. Although an IARC Monograph Working Group concluded that there was limited epidemiologic evidence of the carcinogenicity of welding fumes with lung cancer as the main outcome in 1990, a considerable number of occupational epidemiology studies have found positive associations since then (Kendzia B et al. 2013). Further, a number of these studies have been used by IARC Monograph Working Groups in assessing the evidence of agents found in welding fumes including chromium VI and nickel compounds. Despite the accumulating evidence, the effects of welding activities on risk of lung cancer has been difficult to disentangle within smokers. Active cigarette smoking is the most prominent lifestyle risk factor for lung cancer development and is thought to subsume the potential toxicity of other environmental exposures. The problem is further compounded by the limited sample size and number of lung cancer cases in many studies. Therefore, we propose to assess the dose-response and interaction between occupational welding history and cumulative active smoking in welders, by leveraging the National Lung Screening Trial, a randomized trial comparing screening with low dose CT versus X-rays in a sample of 53, 456 high-risk participants who were former and current smokers.

1a) Compare the distribution of demographic, medical, occupational, and anthropometric characteristics between welders and other participants at baseline.
1b) Compare the rates of lung cancer incidence and mortality between welders and other participants during the follow-up period.
2a) Assess the dose-response relationship between number of years of welding and risk of incident lung cancer and its subtypes, among welders.
2b) Compare the dose-response relationship between pack years of smoking and risk of incident lung cancer and its subtypes, between welders and other participants.
3) Assess the multiplicative interaction between number of years of welding and cumulative pack years of smoking in relation to risk of incident lung cancer, among welders