The Association of Silicosis -4nd Carcinoma

With the exception of the pulmonary tumours occurring among the miners at Schneeberg and Joachimstal and described by Rostoski, Saupe and Schmorl (1) and by Pirchan and Sikl (2) , the rapidly accumulating literature on lung cancer has contained only isolated reports of carcinoma of the lung occurring in association with the various forms of pneumoconiosis. Since both these lesions are being recognized with greater frequency, it may be expected that reports of the coexistence of the two will be increasing. As yet, however, the number of recorded cases of primary lung cancers associated with pneumoconiosis is too small to determine conclusively whether the two conditions are in some way related or whether their association is purely accidental. The data to be presented in this paper indicate that silicosis may be a definite predisposing factor in the development of carcinoma of the lung. The tumours of Schneeberg and Joachimstal will not be considered here because the radioactivity of the dust as well as that of the inhaled air confuses the picture. That this radioactivity is probably of prime import in these cases is suggested by the fact that it is a factor common to both mines ( 2 ) . Apart from these cases a great variety of irritating atmospheric conditions and inhaled dusts have been mentioned as possibly predisposing to lung tumours but in only a few instances has it been possible to establish such a relationship. Investigations of the occupational incidence of pulmonary neoplasms have been of little help. Hruby and Sweany (3 ) found labourers, office workers, and housewives to be most frequently affected, while representatives of other vocations were affected in proportion to their numbers. Analysis of death certificates (which is open to criticism) for England and Wales made by Kennaway and Kennaway (4) indicated that the factors leading to silicosis were not active in predisposing to lung cancer. These investigators, did, however, find that the highest incidence of the latter disease occurred among openair workers exposed to road dusts, with the exception of motor vehicle operators. It is worthy of note that no increased incidence was found among cotton-mule spinners, though these workers inhale oils generally believed capable of producing skin cancers. Twenty of 41 patients suffering from pulmonary neoplastic disease, reported by Frommel ( S ) , were found to have been exposed to various'dusts. Rosedale and McKay ( 6 ) , in reviewing 5 7 cases of carcinoma of the lung were struck by the fact that 75 per cent of the patients had been employed in occupations requiring exposure to dusts or other irritating atmospheric conditions. Advanced pneumoconiosis was found in 14 of their cases, some of which showed marked fibrotic changes. As pointed out by Boyd ( 7 ) , however, it is questionable if air contaminated by automobile fumes or material from tarred roads is of any importance, as he found a high inci-