Diagnostic and therapeutic implications of ectopic hormone production in small cell carcinoma of the lung

Abstract

In 75 unselected and untreated patients with small cell carcinoma of the lung, plasma ACTH, serum calcitonin, and antidiuretic hormone (ADH) in plasma and urine were related to corresponding clinical symptoms and biochemical findings at the time of diagnosis. The significance of elevated concentrations of these substances in relation to treatment was also investigated. Plasma ACTH concentrations were increased in 22 patients (29%), and 25 patients (33%) were considered to have inappropriate ADH secretion. Only one patient had definite hypokalaemic alkalosis, and one patient pronounced hyponatraemia, with associated clinical syndromes of ectopic ACTH and ADH secretion. Serum calcitonin concentrations were increased in 48 patients (65%). No related clinical symptoms were disclosed, and all these patients had normal serum calcium concentrations. Thirty-three of 66 patients (50%) had raised levels of free cortisol in a 24-hour urine and these levels were significantly related to plasma ACTH concentrations. The median survival was slightly shorter in patients with increased values of the three substances, but this was not related to increased plasma ACTH concentrations and was not statistically significant. Survival rates and results of treatment were independent of the pretreatment levels of the three substances.