Researchers Find Gene Mutation in Patient with Lung Cancer-Derived Cushing’s Syndrome

A specific genetic mutation has been found in a patient with Cushing’s syndrome secondary to typical pulmonary carcinoid (TPC), a new Chinese study shows. The finding holds promise for progress in diagnosis and therapy.

The study, “Cushing’s syndrome secondary to typical pulmonary carcinoid with mutation in BCOR gene,” appeared in the journal Medicine.

The senior author in the study was Ying Chai, MD, from the Second Affiliated Hospital’s Department of Thoracic Surgery at Zhejiang University in Hangzhou, China.

TPC is a neuroendocrine tumor with low-grade malignancy. It comprises 1-2% of all primary lung cancers, and its most common treatment strategy is surgical removal.

Ectopic CS consists of excessive production of adrenocorticotropic hormone (ACTH) from a tumor located in an organ that does not normally produce this hormone, such as small-cell lung carcinoma and pulmonary carcinoid. Ectopic CS represents approximately 10% of all CS cases.

Although CS is a rare clinical feature of TPC, cases of CS secondary to TPC have been reported. However, detailed genetic information is still needed to better understand the condition.

This case report describes a 42-year-old man admitted to the hospital for progressive weight gain within one year. The patient was diagnosed with ectopic ACTH syndrome through hormonal tests, which detected high cortisol levels in the urine and serum, and imaging exams. Cushing’s disease (excessive production of ACTH from a pituitary tumor) was excluded because, although increased, ACTH levels were not as high as those seen in Cushing’s disease.

Further imaging detected a pulmonary nodule in the middle lobe of the lung, which the scientists thought to be the ACTH’s source.

The patient underwent a pulmonary wedge resection (a removal of cancerous cells along with surrounding healthy cells). The researchers conducted genetic sequencing after the surgery, which showed a mutation in the BCOR gene that is implicated in programmed cell death and tumor suppression. 

Subsequent histological analysis confirmed the diagnosis of TPC with excessive production of ACTH. The patient recovered well from surgery and had no tumor recurrence for three years. 

The authors note that although BCOR gene mutations had not been reported previously in CS secondary to TPC, they had been observed in other pulmonary neuroendocrine tumors.

Overall, the study suggests that testing BCOR alterations “may become a promising therapeutic target in the future.” Furthermore, this finding may help in early diagnosis of TPC, which currently is difficult. However, targeted therapy for TPC still requires further research, the authors noted.