[Lung cancers synchronous and metachronous with primary malignant neoplasms in other sites]

A series of 19 cases are reported in which, with the exception of one case, two primary malignant tumours developed at different times, one of which in the lung. Some details of this occurrence are discussed in relation to similar findings in the international literature. The average interval between the two tumours was found to be 7.5 years. In eight cases, all male, the lung tumour arose in subjects who had already been subjected to radical treatment for a laryngeal tumour. A lung carcinoma appeared in four women who had been subjected to radiation therapy following mastectomy. This sequence of events was considered a coincidence and not radioinduced in view of the fact that a total of 1061 similarly treated patients were observed over the same period. Finally it is suggested that certain histobiochemical factors induced by the lung tumour may somehow become pathogenically transformed to simulate a new primary malignant tumour.