[Establishment of cohort to study lung cancer in Yunnan tin miners]

To establish a cohort for the study of risk factors of lung cancer, and to support the study of early biomarkers and prevention of lung cancer.

Designed a special population-based prospectively dynamic cohort among radon- and arsenic-exposed tin miners aged 40 or more years old with at least 10 years of occupational exposure in Yunnan Province, P.R.China. The mass screenings with sputum cytology and chest X-ray were conducted annually. The baseline information was collected for assessing demographic characteristics and risk factors. The multiple sputum specimens, chest radiographs and numerous biologic specimens have been collected and stored.

From 1992-1999, 9143 miners have been enrolled and 460 new cases of lung cancer have been found. There had 47655 person-time chest radiographs and 46625 person-time sputum cytology among the cohort in 8 years. The relative risks of age-adjusted exposure to chronic bronchitis, silicosis, and tobacco were 1.73, 1.46, and 1.32 respectively.

A cohort of unique occupationally-exposed tin miners with an extensive biologic specimen repository and data bank has been successfully established. Although occupational exposures are the predominant risk factors among the high risk miners, lung cancer risk is also associated with chronic obstructive lung disease (chronic bronchitis and silicosis) and a number of measures of exposure to tobacco smoke, including early age of first use, duration, and cumulative exposure.