Marked increase in plasma ACTH with tumor reduction after chemotherapy in ectopic ACTH syndrome

We report on a case of rapid and marked hormone release as a result of rapid tumor reduction due to chemotherapy in a 36-year-old woman with ectopic ACTH syndrome due to small cell lung cancer. Treatment of the cancer with cisplatin and etoposide resulted in an 80% reduction in tumor size on computed tomographic scan within two weeks. Concurrently, plasma ACTH exhibited an unexpected and astonishing increase from 373 pg/ml before treatment to more than 1200 pg/ml. There were no biochemical characteristics observed in tumor lysis syndrome of solid tumors such as azotemia, increased LDH and hyperkalemia. The present case indicates that anticancer chemotherapy instituted in patients with ectopic ACTH syndrome could result in an acute increase of plasma ACTH and exacerbation of hypercortisolism, similar to tumor lysis syndrome, which is a potentially fatal complication following anti-cancer chemotherapy.