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March 22, 1993

Ectopic Corticotropin Syndrome and Small-cell Carcinoma of the LungClinical Features, Outcome, and Complications

Author Affiliations

From the Departments of Medicine (Drs Delisle, Boyer, Warr, and Feld) and Radiation Oncology (Drs Payne and Yeoh), Princess Margaret Hospital, Toronto, Ontario; and Department of Medicine, St Joseph's Health Center, London, Ontario (Dr Killinger).

Arch Intern Med. 1993;153(6):746-752. doi:10.1001/archinte.1993.00410060054009

Background:  Ectopic corticotropin syndrome is a rare complication of small-cell lung cancer (SCLC). There is little information concerning this syndrome available in the literature. We therefore reviewed all cases of ectopic corticotropin syndrome seen at our institution during a 20-year period.

Methods:  Cases were identified by searching a computerized database and reviewing the charts of all 840 patients with SCLC seen between 1971 and 1991. Patients were included if they met at least two of the following criteria: spontaneous hypokalemia (potassium level, <3.2 mmol/L); plasma cortisol level greater than 600 nmol/L; 24-hour urinary free cortisol level greater than 400 nmol/d; and plasma corticotropin level greater than 22 pmol/L. Data were abstracted from the patients' medical records.

Results:  Of 840 patients with SCLC, 14 (1.6%) had ectopic corticotropin production. This was diagnosed at the time of presentation with SCLC in seven patients and from 3 to 19 months later in the remainder. Five patients had limited disease and nine had extensive disease. One or more features of Cushing's syndrome were observed in 57% of patients, but the entire syndrome occurred rarely. Spontaneous hypokalemia was present in all patients, and 10 patients (71%) had hyperglycemia. There were two complete responses and one partial response to chemotherapy, giving an overall response rate of 21%, and the median survival was 5.5 months. Ten patients died of progressive growth of tumor, while three patients died of infections. In one other patient, infection probably contributed to death. A high rate of nonfatal infections was also seen.

Conclusions:  The occurrence of SCLC with ectopic corticotropin syndrome is associated with poor survival, and a high incidence of infective complications, in patients treated with chemotherapy.(Arch Intern Med. 1993;153:746-752)