LUNG TUMOURS AND ACTH PRODUCTION

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Abstract
ACTH levels measured by N- and C-terminal immunoassays and cytochemical bioassay, were measured in 14 lung tumors not associated with the ectopic ACTH syndrome and in macroscopically normal lung tissue taken from the same patients at thoracotomy. Significant concentrations of immunoactive (> 3 ng/g wet weight) and bioactive (> 0.2 ng/g wet weight) ACTH were found in all carcinoid and oat cell tumors (n = 9), a combined tumor (poorly differentiated adenocarcinoma with large cell carcinoid elements), and a poorly differentiated squamous cell tumor. All carcinoid tumors contained more C- than N-terminal ACTH immunoactivity. The squamous cell tumors (n = 2), anaplastic tumors (n = 2) and adenocarcinoma contained insignificant ACTH levels. There was a good correlation between the ACTH levels and the presence of secretory granules in the tumors examined ultrastructurally. All macroscopically normal samples of lung tissue contained immuno and bioactive ACTH-like material, the levels of which correlated well with ACTH levels in the tumor tissue. All lung tumors of carcinoid or oat cell type synthesize ACTH-like materials although clinical evidence of the ectopic ACTH syndrome may be absent. The presence of ACTH-like materials in nontumorous lung tissue in patients with lung cancer may indicate a low level of ACTH production throughout the lung or sequestration of ACTH containing granules secreted by the tumor.