• Clinical medicine

Research published in this journal and elsewhere has demonstrated an increased risk of pneumoconiosis and more recently chronic obstructive pulmonary disease among coal miners. Despite this extensive research base, many puzzles remain such as the deficit of lung cancer reported in many studies of coal miners. These findings are surprising since in addition to coal dust, miners are exposed to other substances that are widely recognised as causing respiratory cancer in humans, most notably silica,1 but also diesel exhaust and radon gas. We have chosen for this editorial two landmark papers from the journal archives that addressed this as yet unresolved issue.

In his 1955 article, Primary lung cancer in South Wales coal-workers with pneumoconiosis,2 James described the autopsy findings of approximately 1800 coal miners and 1500 non-miners who died in South Wales between 1947 and 1952. Lung cancer was found to be less common in coal miners (3.3%) than in non-miners (5.4%). Furthermore, the proportion of lung cancers appeared to be inversely related to the severity of pulmonary disease in the coal miners, being 5.1% among individuals with simple pneumoconiosis and only 1.4% among individuals with progressive massive fibrosis. Based on his study and previous autopsy studies with similar findings,3–5 James concluded that the findings “do not suggest that inhaled coal dust is carcinogenic”.

Goldman in his 1965 article,6 Mortality of coal-miners from carcinoma of the lung, presented a review of findings from several published studies and unreported investigations that supported the hypothesis that “mortality from cancer of the lung is appreciably lower for coal-miners than for other men of similar age”. He gives credit for the initial discovery to Kennaway and Kennaway who reported in 1936 that lung cancer mortality among coal miners was approximately 50% lower than among men in other …