Cushing’s Syndrome Eludes Treatment Paradigm or Standard Approach to Care

Results of two systematic reviews indicate that while surgery is the preferred treatment, many patients present with contraindications without an accepted management paradigm leaving clinicians to follow a patient-centric approach to care.

With commentary by Eliza B. Geer, MD

Cushing’s syndrome may arise from an endogenous glucocorticoid excess is either adrenocorticotropic hormone (ACTH)-dependent or ACTH-independent; each variation has numerous underlying causes, including pituitary tumor, adrenal tumor, or other unknown causes.

Although rare, ectopic Cushing’s syndrome results from a non-pituitary ACTH-producing source. Cushing’s disease, a type of Cushing’s syndrome, affects an estimated 1.2 to 2.4 million people each year, and is caused by an ACTH-secreting pituitary adenoma.1

While surgery is preferred for treatment of Cushing's syndrome many patients need a medical approach instead.

Gaining insights into treatment preferences and efficacy for Cushing’s syndrome were the focus of two separate systematic reviews and meta-analyses, both published in the journal, Pituitary: one regarding medical treatments for Cushing’s syndrome,2 and the other comparing endoscopic versus microscopic transsphenoidal surgery for Cushing’s disease.3

Assessing Medical Management of Cushing’s Syndrome

The meta-analysis examining medical care of individuals with Cushing’s syndrome encompassed 1520 total patients across 35 studies, most of whom had Cushing’s disease.2 However, only 2 of the 35 studies were randomized trials, highlighting the lack of and clear need for controlled clinical trials on medical therapies for Cushing’s syndrome.

Surgery is typically first-line treatment—whether transsphenoidal pituitary adenomectomy for Cushing’s disease,4 removal of the ACTH-producing tumor in ectopic Cushing’s syndrome or adrenalectomy in ACTH-independent Cushing’s syndrome.5

However, many patients require medical therapy owing to contraindications for surgery, for recurrent disease, or to control cortisol secretion prior to surgery or radiotherapy. Results of the meta-analysis reflected wide-ranging normalization of cortisol levels depending upon the agent used– from 35.7% for cabergoline to nearly 82% for mitotane in Cushing’s disease.2 Combination therapy (medications used either together or sequentially) was shown to increase effectiveness in normalizing cortisol levels.2

In an interview with EndocrineWeb, Eliza B. Geer, MD, medical director of the Multidisciplinary Pituitary and Skull Base Tumor Center at Memorial Sloan Kettering Cancer Center in New York City, noted that most medical therapies for Cushing’s syndrome are used off-label (in the US), and thus may lack clinical trial efficacy and safety data; consequently, this review provides useful information for treatment selection. However, Dr. Geer said there was substantial diversity of treatments reviewed in this paper – including tumor-directed therapies, cortisol synthesis inhibitors, an adrenolytic therapy, and a receptor blocker, used alone or in combination.

Further, treatments used in the studies addressed a range of Cushing’s etiologies and reflected heterogeneous study designs (for example follow-up ranged from 2 weeks to 11.5 years).2  As such, she said, “findings provided by this review should be viewed in the context of a broader clinical understanding of Cushing’s treatment.”

Specifically, Dr. Geer said, “Dr. Broersen’s analysis found that efficacy of medical therapy was improved by prior radiotherapy. But we know that radiotherapy is recommended on an individualized basis in only a fraction of Cushing’s patients, depending on tumor behavior and treatment history. Also, the fact that mitotane was shown here to have the highest efficacy of all therapies does not make this the appropriate treatment for all, or even most, Cushing’s patients; mitotane is adrenolytic and has a high rate of significant adverse effects.”

Too Many Questions Persist, Necessitating Focus on Attaining Management Paradigm

Dr. Geer also highlighted the need for answers to basic questions when investigating Cushing’s treatments: How do we define ‘successful’ treatment? What goals of care can patients expect? Which cortisol measurements and cut-offs can be used? How do we define clinical remission—resolution of which symptoms and comorbidities? She said Cushing’s syndrome is one of the most challenging endocrine diseases to treat because of the lack of an accepted, universal treatment or management paradigm.

Treatment is often multimodal and always multidisciplinary, with patient-specific decision trees that must consider many factors, including goals of care, treatment history, disease etiology and severity, tumor behavior, and individual responses to medical therapies, she told EndocrineWeb.

She concluded, “While Broersen et al’s study provides a useful review of available medical therapies, it reinforces something we already know about the treatment of Cushing’s: Expertise is required.”

Pituitary surgery is first-line treatment for Cushing’s disease. Currently, there are two main techniques for transsphenoidal pituitary surgery: microscopic and endoscopic. The operating microscope provides three-dimensional vision and may be advantageous in identifying small tumors; the broader field of vision afforded by the endoscope may be advantageous for complete resection of large tumors.3  Generally, despite an absence of studies directly comparing relative remission and complication rates between microscopic versus endoscopic approaches, most surgical centers choose to use one or the other; few have both.3

Examining the Surgical Options to Manage Cushing’s Disease

The second systematic review is the first to compare remission and recurrence rates, and mortality after microscopic versus endoscopic transsphenoidal pituitary surgery for Cushing’s disease.3 The review included 97 studies of 6695 patients: 5711 individuals having the microscopic procedure and 984 undergoing endoscopic surgery.

Results of the meta-analysis found no clear difference between the two techniques in overall remission (80%) or recurrence (10%).3 Short-term mortality for both techniques was < 0.5%. However, endoscopic surgery was associated with a greater occurrence of cerebrospinal fluid leak (12.9 vs 4.0%) but a lesser occurrence of transient diabetes insipidus (11.3 vs 21.7%).3

The authors reported a higher percentage of patients in remission (76.3 vs. 59.9%) and lower percentage recurrence rates (1.5 vs 17.0%) among patients undergoing endoscopic surgery for macroadenomas.3

When interviewed regarding the second meta-analysis,3 Dr. Geer said that the potential benefit of endoscopy over microscopy has been questioned for ACTH-secreting tumors specifically since most are microadenomas.

“With the caveat that few studies (four of the 97 reviewed) compared techniques directly, Broersen et al3 found that endoscopic surgery was associated with higher remission rates compared to microscopic surgery for large tumors, but the two techniques were comparable for small tumors,” said Dr. Geer, however, “one limitation of these data is the lack of standardized criteria to define diagnosis and remission of Cushing’s among the studies reviewed.”

Need for Consistency in Clinical Trials and Surgical Expertise

The study investigators concluded, “endoscopic surgery for patients with Cushing’s disease reaches comparable results for microadenomas, and probably better results for macroadenomas than microscopic surgery,” despite the greater learning curve associated with endoscopic surgery.3 As such, based on their findings, the authors concluded that “endoscopic surgery may thus be considered the current standard of care. Microscopic surgery can be used based on neurosurgeon’s preference.” They did not respond to EndocrineWeb for a request for comment.

As more neurosurgeons receiving training with the endoscope, the preferred technique for pituitary surgery is changing. Dr. Geer said, “Broersen’s review provides reassurance that the newer endoscopic technique is at least equal to the microscope for microadenomas and may be preferred for macroadenomas.”

“However, [conclusions based on the systematic review] do not change our role as endocrinologists treating Cushing’s disease, which is to refer, when indicated, to the available neurosurgeon with the most favorable outcomes and lowest rate of complications, both of which depend directly on level of experience with the procedure and the instrument being used, whether endoscope or microscope,” she said.

The authors had no financial conflicts to declare.

From https://www.endocrineweb.com/professional/cushings/cushings-syndrome-eludes-treatment-paradigm-standard-approach-care

Tumors in Cushing’s Patients Have Distinct Genetic Profiles

A study examining the genes expressed in pituitary tumors of Cushing’s disease patients found that these tumors may be grouped into three distinct subsets.

The finding suggests that different biological processes contribute to the development of each subset, an insight that may aid in developing targeted therapies.

The study, “Gene expression profiling in human corticotrope tumors reveals distinct, neuroendocrine profiles,” was published in the Journal of Neuroendocrinology.

In Cushing disease, a pituitary tumor producing excess amounts of the adenocorticotropic hormone causes the body to produce too much cortisol.

Pituitary tumors respond differently to modulators of ACTH secretion, and patients have different disease manifestations, but what makes them differ from one another is unknown.

To determine if the genetic profile of tumors could explain the clinical diversity reported in these patients, Italian researchers evaluated 40 benign, ACTH-secreting pituitary tumors removed from patients with Cushing’s disease.

Of the 20,815 genes examined in the study, 1,259 were significantly elevated in the pituitary tumors. These were mostly involved in pathways that kept the neuroendocrine cell profile.

Based on their genetic profile, researchers were able to cluster tumors into three distinct subgroups. Samples in group A had four specific genes, associated with tumor-related processes, that were overly active. In group B, there were 313 overly active genes, involved in many of the mechanisms of hormone-secreting adenomas.

Group C had 29 highly active genes, all involved in calcium influx and cell growth – mechanisms that are important for the development of ACTH-secreting adenomas.

“It appears that these tumors present a neuroendocrine cell profile but, at the same time, clearly distinct gene expression patterns [are seen] in individual subgroups,” the researchers wrote.

Looking at clinical characteristics that correlated with each subgroup, the researchers found that most group A patients  had macroadenomas (large tumors) that had invaded the sella – the compartment where the pituitary gland resides at the base of the brain. These patients were also older than those in the other two subgroups.

Some patients in group B also had macroadenomas, but no such tumors were seen in group C. However, researchers found no association between the groups and the hormonal values, clinical findings, or surgical outcomes.

Collectively, the findings add new clues to the molecular mechanisms involved in the progression of benign pituitary tumors. They also provide new ground for developing targeted therapies, the researchers said.

From https://cushingsdiseasenews.com/2018/06/22/tumors-in-cushing-disease-patients-show-distinct-genetic-profiles-study-reports/

Cushing’s Patients at Risk of Life-threatening Pulmonary Fungal Infection

Cushing’s disease patients who exhibit nodules or masses in their lungs should be thoroughly investigated to exclude fungal infection with Cryptococcus neoformans, a study from China suggests.

While rare, the infection can be life-threatening, showing a particularly worse prognosis in patients with fluid infiltration in their lungs or with low white blood cell counts in their blood.

The study, “Cushing’s disease with pulmonary Cryptococcus neoformans infection in a single center in Beijing, China: A retrospective study and literature review,” was published in the Journal of the Formosan Medical Association.

Cortisol, a hormone that is produced in excess in Cushing’s disease patients, is a kind of glucocorticoid that suppresses inflammation and immunity. Consequently, subjects exposed to cortisol for long periods, much like immuno-compromised patients, are at high risk for infections.

In Cushing’s patients, the most common infections include Pneumocystis jiroveciAspergillus fumigatus, and Cryptococcosis — 95 percent of which are caused by C. neoformans.

But while “Cushing’s disease patients are susceptible to C. neoformans, the association between pulmonary C.neoformans and [Cushing’s disease] is poorly explored,” researchers said.

In an attempt to understand the clinical characteristics of Cushing’s patients who develop C.neoformans infections, researchers in Beijing, China, reviewed the clinical records of six patients at their clinical center.

Their analysis also included six other patients whose cases had been reported in previous publications.

Patients had a mean age of 44 and 10 were diagnosed initially with high blood pressure. Seven also had diabetes mellitus.

All patients had elevated cortisol levels in their urine and high levels of the adrenocorticotropic hormone (ACTH). Ultimately, all patients were found to have masses in their pituitary glands, causing the high cortisol and ACTH levels.

Patients complained of lung symptoms, including shortness of breath after physical activity, cough, and expectoration. But they had no fever or signs of blood in the lungs, which could suggest lung infection.

A CT scan of the chest then revealed lung nodules in four patients, and lung masses in five patients. Four patients, including one with a lung mass, also had lung air spaces filled with some material (pulmonary consolidation), which was consistent with pulmonary infection.

After analyzing lung nodule/mass biopsies, lung fluids, or blood samples, all patients were diagnosed with C. neoformans pulmonary cryptococcosis.

For their infection, patients received anti-fungal drugs, including amphotericin-B, fluconazole, flucytosine, and liposomal amphotericin. Cushing’s disease, however, was treated with surgery in 10 patients and ketoconazole in two patients.

Despite the treatments, five patients died during follow-up, including four who experienced co-infections or spreading of the cryptococcal infection and one patient with extensive bleeding after surgical removal of the gallbladder.

Among them, two patients had significantly low white blood cell levels and elevated cortisol levels, and four had infiltration in their lungs, suggesting these are markers of poor prognoses.

Researchers also noted that the patients who received ketoconazole died during in the reviewed studies. They attribute this to ketoconazole’s anti-fungal properties, which may interfere with its ability to manage Cushing’s symptoms.

Given the high susceptibility of Cushing’s disease patients to C. neoformans infections, “pulmonary nodules or masses should be aggressively investigated to exclude” this potentially fatal opportunistic infection, the researchers suggested.

“The infiltration lesions in chest CT scan and lymphopenia seem to be potential to reflect the poor prognosis,” they said.

From https://cushingsdiseasenews.com/2018/06/15/pulmonary-fungal-infection-threatens-cushings-disease-patients-study/

Radiation to the Whole Pituitary Compartment Effective at Controlling Cushing’s

Radiation therapy targeting the entire sella — the compartment where the pituitary gland resides at the base of the brain — is effective at controlling Cushing’s disease and should be considered for patients with suspected invasive adenoma tumors, a new study shows.

The study, “Technique of Whole-Sellar Stereotactic Radiosurgery for Cushing’s Disease: Results from a Multicenter, International Cohort Study,” was published in the journal World Neurosurgery.

In patients with Cushing’s disease, excess cortisol levels are caused by a kind of pituitary tumor (adenoma)  that secretes too much adrenocorticotropic hormone (ACTH).

Removing the adenoma using the transsphenoidal approach — a minimally invasive procedure performed through the nose to remove pituitary tumors — remains the first-line treatment for patients with newly diagnosed Cushing’s syndrome. For patients who fail surgery and medical management, stereotactic radiosurgery (SRS) may be used.

SRS is not a surgery in the traditional sense, as it does not require an incision. Instead, SRS uses many focused radiation beams to treat tumors and other problems in the brain, neck and other parts of the body.

While surgery may achieve very good remission rates in patients with an identifiable adenoma, as many as 50 percent of Cushing’s disease patients have no identifiable adenoma on magnetic resonance imaging (MRI) scans. In such cases, surgeons can opt for SRS targeting the entire sella, a procedure called whole-sellar SRS. However, the outcomes of whole-sellar SRS are not fully known.

Researchers conducted an international, retrospective study to analyze the outcomes of Cushing’s disease patients who received whole-sellar SRS.

The study enrolled 68 patients, including 52 who received the procedure for persistent disease, nine whose disease returned after surgery, and seven as their initial treatment.

Patients underwent a type of SRS known as gamma knife radiosurgery (GKRS), which uses small beams of gamma rays to target and treat brain tumors. They were then followed for a mean of 5.3 years.

Whole-sellar SRS was effective at controlling the disease, researchers found. In the five years after receiving the treatment, 75.9 percent of patients achieved a remission. Of those, 86% remained recurrence-free for five or more years.

The mean volume of area targeted using whole-sellar SRS was 2.6 cm3. Researchers discovered that treatment volumes greater than 1.6 cm3 were associated with a shorter time to remission, indicating that targeting a larger portion is more beneficial.

Also, statistical analysis revealed that a reduced dose of radiation was linked to recurrence, suggesting that a higher dose is more advantageous.

Regarding adverse events, 22.7% of patients who underwent whole-sellar SRS developed loss of one or more pituitary hormones.

Researchers also compared outcomes of patients who underwent whole-sellar SRS to those who received adenoma-targeted SRS, of which the latter involves irradiating only the tumor.

Interestingly, there were no differences in remission rate, time to remission, recurrence-free survival, or new endocrine disease development between both groups.

“Whole-sellar GKRS is effective at controlling [Cushing’s disease] when an adenoma is not clearly defined on imaging or when an invasive adenoma is suspected at the time of initial surgery,” the researchers concluded.

From https://cushingsdiseasenews.com/2018/05/25/precise-radiation-pituitary-sella-effective-control-cushings-study/

Endoscopic Surgery Should Be Standard for Cushing’s Patients with Large Tumors

Cushing’s disease patients with macroadenomas — pituitary tumors larger than 10 mm — should undergo transsphenoidal pituitary surgery using the endoscopic technique, according to a new systematic review.

The study, “Endoscopic vs. microscopic transsphenoidal surgery for Cushing’s disease: a systematic review and meta-analysis,” was published in the journal Pituitary.

Cushing’s disease develops due to an adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma. The first-choice treatment for Cushing’s disease is transsphenoidal pituitary surgery, which is performed through the nose to remove pituitary tumors.

There are two main methods to conduct this kind of surgery: microscopic, which is done using a magnifying tool, and endoscopic surgery, which uses a thin, lighted tube with a tiny camera. The microscopic technique was the established method for transsphenoidal surgery, until physicians started doing endoscopic pituitary surgery in 1992.

Most surgical centers choose to perform either the microscopic or endoscopic technique but do not offer both. As a result, only a few small studies have compared the outcomes of microscopic and endoscopic surgical techniques in Cushing’s disease performed at the same center. These studies showed no clear differences in remission rates or surgical morbidity.

To date, no systematic review comparing the microscopic and the endoscopic surgical techniques in Cushing’s disease has been conducted and, therefore, convincing evidence to support either technique is lacking.

To address this, researchers set out to conduct a systematic review and meta-analysis that compares the endoscopic and microscopic transsphenoidal surgery techniques for Cushing’s disease with regards to surgical outcomes and complication rates.

Researchers searched through nine electronic databases to identify potentially relevant articles. In total, 97 cohort studies with 6,695 patients were included in the study. Among the total patient population, 5,711 received microscopical surgery and 984 were endoscopically operated.

Overall remission was achieved in 80 percent of patients, with no clear differences between the techniques. The recurrence rate was around 10 percent, and short-term mortality was less than 0.5 percent.

Cerebrospinal fluid leak (due to a hole or a tear) occurred more often in patients who underwent endoscopic surgery. On the other hand, transient diabetes insipidus — short-term diabetes — occurred more often in patients who received endoscopic surgery.

When classifying patients by tumor size, however, researchers found that patients with macroadenomas — tumors larger than 10 mm — had higher rates of remission and lower recurrence rates after endoscopic surgery. Patients with microadenomas (tumors smaller than 10 mm) had comparable outcomes with either technique.

“Endoscopic surgery for patients with Cushing’s disease reaches comparable results for microadenomas, and probably better results for macroadenomas than microscopic surgery,” the investigators wrote.

Taking these results into account, the researchers suggest that endoscopic surgery may be considered the current standard of care, though microscopic surgery can be used based on the neurosurgeon’s preference.

They also emphasize that centers that solely perform the microscopic technique should consider at least referring Cushing’s disease patients with macroadenomas to a center that performs the endoscopic technique.

From https://cushingsdiseasenews.com/2018/05/24/endoscopic-surgery-more-effective-macroadenomas-cushings-study/

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