Pituitary surgery cures a third of Cushing’s disease patients: Study

Low remission rate might be due to nonspecialists performing procedure

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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This is an illustration of a person's head, viewed from the side so it is easy to see the transparent image of the brain.

Surgery to remove a tumor in the brain’s pituitary gland cured about a third of people with Cushing’s disease in a recent Thai study, a remission rate markedly lower than the 80-90% rate reported in other studies.

Researchers believe the low rate might have been due to some surgeries being performed by doctors at academic institutions who weren’t specialized in the procedure.

“This is the first work that studied the countrywide prevalence, presentation, and outcome of pituitary tumors in Thailand,” the researchers wrote in “Pituitary adenomas registry in Thailand,” which was published in the Journal of Clinical Neuroscience. “A health promotion system aiming to improve patient and physician awareness and recognition may improve the prognosis of these diseases.”

In Cushing’s disease, pituitary tumors release too much adrenocorticotropic hormone (ACTH), which signals the adrenal glands on top of the kidneys to produce excessive amounts of the hormone cortisol. It’s this excess, called hypercortisolism, that’s at the root of the wide range of Cushing’s symptoms.

Pituitary adenomas — a type of hormone-producing tumor that often cause Cushing’s disease — is linked to conditions with high levels of hormones other than ACTH.These tumors are usually noncancerous (benign) and progress slowly, meaning they may go undiagnosed for a long time.

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Ectopic pituitary tumor is culprit in rare Cushing’s case

Case of pituitary adenomas evaluated

Data are lacking on the prevalence, characteristics, and outcomes of pituitary adenomas in Thailand, where the research team is based, leading scientists to create a census of pituitary tumors by examining clinical information of patients diagnosed at any of 11 academic medical centers in the country between October 2011 and September 2014. A total of 1,283 cases were identified — 49 associated with Cushing’s disease (3.82%).

There were also patients with prolactinomas (29.38%), acromegaly (14.65%), gonadotropin-producing tumors (1.01%), and thyroid stimulating hormone-producing tumors (0.62%). Prolactinomas are tumors that release an excessive amount of prolactin hormone. Acromegaly is a hormonal disorder caused by a tumor that produces high amounts of growth hormone. The remaining half of the cases were considered nonfunctioning adenomas, meaning they weren’t associated with abnormal hormone release.

Of the Cushing’s patients, most (89.80%) were female, with a mean age of about 39. Patients had experienced symptoms for a mean of 16.6 months, nearly 1.5 years.

A physician’s examination often found abnormal weight gain (70.7%), high blood pressure (29.3%), and  hypopituitarism, which occurs when the pituitary gland fails to produce enough of certain hormones (26.5%).

In most Cushing’s cases (70.7%), the tumor was considered a microadenoma, meaning it was small, with a diameter measuring less than a centimeter. Across the entire group of patients, only 28.8% had a microadenoma.

Overall, 46 Cushing’s patients had surgery to remove the pituitary tumor. In most (95.7%), the surgery was transphenoidal, or conducted through the nasal sinuses. Six people also received radiation therapy to kill tumor cells.

Surgery led to a complete cure for 15 patients (31.3%) and to an improvement for 26 (54.2%). In the larger group of pituitary adenoma patients, a cure was observed in 10.4% and an improvement in 72.4%.

Lower than reported cure rate

These cure rates were lower than what’s been reported. For example, while rates vary, pituitary surgery is reported to result in remission in up to 80-90% of Cushing’s disease patients, leading the researchers to note that success rates depend on “size and location of the tumor, and surgical experience.”

Scientists believe the relatively low cure rates seen here may be due to the fact that “many surgeries may have been done by general neurosurgeons” who had no expertise in pituitary surgeries. Success rates are higher when the procedure is conducted by specialists in pituitary surgery.

During follow-up, 23 Cushing’s disease patients (53.5%) saw new onset adrenal insufficiency, which occurs when the adrenal glands don’t make enough steroid hormones, including cortisol. In some patients, the production of thyroid (25.6%) or sex hormones (18.6%) was also diminished. No Cushing’s disease patient died over a mean follow-up of nearly 3.5 years.

While the study was limited by some missing data and the use of cases collected at academic medical centers, the findings provide the first holistic picture of pituitary adenomas in Thailand, according to the researchers, who said the relatively low rates of complete remission, may help to advocate for concentrating pituitary surgeries among a smaller number of neurosurgeons in pituitary tumors centers of excellence.”