Cerebrospinal fluid vasopressin as a marker of central nervous system metastases from small-cell bronchogenic carcinoma.

Abstract

Vasopressin (ADH) was measured in CSF and plasma in 75 evaluable patients with known or suspected CNS metastases from small-cell bronchogenic carcinoma (SCBC), and in 66 control patients having neither malignant disease nor organic CNS disease. The presence of CNS metastases was confirmed or excluded on the basis of computed tomographic scans, neurologic examination, and autopsy. Twenty-four of the 75 patients had no CNS metastases. Ten of the 51 patients with CNS metastases had leptomeningeal carcinomatosis (MC). CSF-ADH was significantly increased in patients with MC (P less than .05), but not in patients having exclusively parenchymatous CNS metastases. Taking 2 pg/mL (95th percentile of control patients) as the upper limit of normal, 15 SCBC patients had elevated CSF-ADH, including 12 patients with CNS metastases and six patients with MC. The CSF-ADH to plasma ADH ratio was significantly increased in patients with CNS metastases (P less than .05). Patients without CNS metastases had a ratio less than or equal to 0.8 whereas the ratio was greater than 0.8, in 21 of the 51 patients with CNS metastases. The positive and negative predictive values with 95% confidence limits were 84% to 100% and 31% to 59%, respectively. Patients with inappropriate secretion of ADH (SIADH) constituted a significantly greater proportion of patients with elevated CSF-ADH than of patients with normal CSF-ADH levels (P less than .05). In addition, patients with SIADH constituted a significantly greater proportion of patients with MC than of patients with parenchymatous metastases (P less than .05). The diagnostic application of these findings is limited because of the large number of false-negative results, but it may prove to be of value in conjunction with the measurement of other tumor markers.