The hypothalamus-pituitary function after pituitary stereotactic radiosurgery: evaluation of growth hormone deficiency

Intensity-modulated radiotherapy for cushing's disease: single-center experience in 70 patients

Context

Intensity-modulated radiotherapy (IMRT) is a modern precision radiotherapy technique for the treatment of the pituitary adenoma.

Objective

Aim to investigate the efficacy and toxicity of IMRT in treating Cushing's Disease (CD).

Methods

70 of 115 patients with CD treated with IMRT at our institute from April 2012 to August 2021 were included in the study. The radiation doses were usually 45-50 Gy in 25 fractions. After IMRT, endocrine evaluations were performed every 6 months and magnetic resonance imaging (MRI) annually. Endocrine remission was defined as suppression of 1 mg dexamethasone test (DST) or normal 24-hour urinary free cortisol level (24hUFC). The outcome of endocrine remission, endocrine recurrence, tumor control and complications were retrieved from medical record.

Results

At a median follow-up time of 36.8 months, the endocrine remission rate at 1, 2, 3 and 5 years were 28.5%, 50.2%, 62.5% and 74.0%, respectively. The median time to remission was 24 months (95%CI: 14.0-34.0). Endocrine recurrence was found in 5 patients (13.5%) till the last follow-up. The recurrence-free rate at 1, 2, 3 and 5 years after endocrine remission was 98.2%, 93.9%, 88.7% and 88.7%, respectively. The tumor control rate was 98%. The overall incidence of new onset hypopituitarism was 22.9%, with hypothyroidism serving as the most common individual axis deficiency. Univariate analysis indicated that only higher Ki-67 index (P=0.044) was significant favorable factors for endocrine remission.

Conclusion

IMRT was a highly effective second-line therapy with low side effect profile for CD patients. Endocrine remission, tumor control and recurrence rates were comparable to previous reports on FRT and SRS.

Dose to neuroanatomical structures surrounding pituitary adenomas and the effect of stereotactic radiosurgery on neuroendocrine function: an international multicenter study

OBJECTIVE

Stereotactic radiosurgery (SRS) provides a safe and effective therapeutic modality for patients with pituitary adenomas. The mechanism of delayed endocrine deficits based on targeted radiation to the hypothalamic-pituitary axis remains unclear. Radiation to normal neuroendocrine structures likely plays a role in delayed hypopituitarism after SRS. In this multicenter study by the International Radiosurgery Research Foundation (IRRF), the authors aimed to evaluate radiation tolerance of structures surrounding pituitary adenomas and identify predictors of delayed hypopituitarism after SRS for these tumors.

METHODS

This is a retrospective review of patients with pituitary adenomas who underwent single-fraction SRS from 1997 to 2019 at 16 institutions within the IRRF. Dosimetric point measurements of 14 predefined neuroanatomical structures along the hypothalamus, pituitary stalk, and normal pituitary gland were made. Statistical analyses were performed to determine the impact of doses to critical structures on clinical, radiographic, and endocrine outcomes.

RESULTS

The study cohort comprised 521 pituitary adenomas treated with SRS. Tumor control was achieved in 93.9% of patients over a median follow-up period of 60.1 months, and 22.5% of patients developed new loss of pituitary function with a median treatment volume of 3.2 cm3. Median maximal radiosurgical doses to the hypothalamus, pituitary stalk, and normal pituitary gland were 1.4, 7.2, and 11.3 Gy, respectively. Nonfunctioning adenoma status, younger age, higher margin dose, and higher doses to the pituitary stalk and normal pituitary gland were independent predictors of new or worsening hypopituitarism. Neither the dose to the hypothalamus nor the ratio between doses to the pituitary stalk and gland were significant predictors. The threshold of the median dose to the pituitary stalk for new endocrinopathy was 10.7 Gy in a single fraction (OR 1.77, 95% CI 1.17-2.68, p = 0.006).

CONCLUSIONS

SRS for the treatment of pituitary adenomas affords a high tumor control rate with an acceptable risk of new or worsening endocrinopathy. This evaluation of point dosimetry to adjacent neuroanatomical structures revealed that doses to the pituitary stalk, with a threshold of 10.7 Gy, and doses to the normal gland significantly increased the risk of post-SRS hypopituitarism. In patients with preserved pre-SRS neuroendocrine function, limiting the dose to the pituitary stalk and gland while still delivering an optimal dose to the tumor appears prudent.

Pituitary disease in pediatric brain tumor survivors

INTRODUCTION

Treatment of childhood brain tumors, including surgical resection and especially external beam radiation, often results in endocrine complications manifested by hypopituitarism, which can involve growth hormone deficiency, hypothyroidism, adrenal insufficiency, disorders of puberty, diabetes insipidus, and hypothalamic obesity.

AREAS COVERED

A comprehensive literature search was conducted on Medline (publications from the 1990s to 01/2019) including systematic reviews, meta-analyses, longitudinal controlled studies, retrospective cohort studies, and case reports. Herein, we present an up-to-date review of the current literature regarding endocrine sequellae of childhood brain tumor survivors.

EXPERT OPINION

Late endocrine sequellae can arise many years after the initial treatment of tumor, so at least annual surveillance of growth, puberty, weight, development, and endocrine status is recommended for at least 10 years after tumor therapy. This follow up should encompass childhood and adulthood among survivors. If found early, outcomes of endocrinopathies are favorable when treated appropriately. Newer tumor therapy modalities, such as proton beam radiation, offer the potential for fewer endocrine complications, but such benefit has yet to be demonstrated, and more research into short- and long-term outcomes is needed.

The Treatment of Cushing's Disease

Cushing's disease (CD), or pituitary-dependent Cushing's syndrome, is a severe endocrine disease caused by a corticotroph pituitary tumor and associated with increased morbidity and mortality. The first-line treatment for CD is pituitary surgery, which is followed by disease remission in around 78% and relapse in around 13% of patients during the 10-year period after surgery, so that nearly one third of patients experience in the long-term a failure of surgery and require an additional second-line treatment. Patients with persistent or recurrent CD require additional treatments, including pituitary radiotherapy, adrenal surgery, and/or medical therapy. Pituitary radiotherapy is effective in controlling cortisol excess in a large percentage of patients, but it is associated with a considerable risk of hypopituitarism. Adrenal surgery is followed by a rapid and definitive control of cortisol excess in nearly all patients, but it induces adrenal insufficiency. Medical therapy has recently acquired a more important role compared to the past, due to the recent employment of novel compounds able to control cortisol secretion or action. Currently, medical therapy is used as a presurgical treatment, particularly for severe disease; or as postsurgical treatment, in cases of failure or incomplete surgical tumor resection; or as bridging therapy before, during, and after radiotherapy while waiting for disease control; or, in selected cases, as primary therapy, mainly when surgery is not an option. The adrenal-directed drug ketoconazole is the most commonly used drug, mainly because of its rapid action, whereas the glucocorticoid receptor antagonist, mifepristone, is highly effective in controlling clinical comorbidities, mainly glucose intolerance, thus being a useful treatment for CD when it is associated with diabetes mellitus. Pituitary-directed drugs have the advantage of acting at the site responsible for CD, the pituitary tumor. Among this group of drugs, the dopamine agonist cabergoline and the somatostatin analog pasireotide result in disease remission in a consistent subgroup of patients with CD. Recently, pasireotide has been approved for the treatment of CD when surgery has failed or when surgery is not an option, and mifepristone has been approved for the treatment of Cushing's syndrome when associated with impairment of glucose metabolism in case of the lack of a surgical indication. Recent experience suggests that the combination of different drugs may be able to control cortisol excess in a great majority of patients with CD.

Hypopituitarism after stereotactic radiosurgery for pituitary adenomas

BACKGROUND

Studies of new-onset Gamma Knife stereotactic radiosurgery (SRS)-induced hypopituitarism in large cohort of pituitary adenoma patients with long-term follow-up are lacking.

OBJECTIVE

We investigated the outcomes of SRS for pituitary adenoma patients with regard to newly developed hypopituitarism.

METHODS

This was a retrospective review of patients treated with SRS at the University of Virginia between 1994 and 2006. A total of 262 patients with a pituitary adenoma treated with SRS were reviewed. Thorough endocrine assessment was performed immediately before SRS and in regular follow-ups. Assessment consisted of 24-hour urine free cortisol (patients with Cushing disease), serum adrenocorticotropic hormone, cortisol, follicle-stimulating hormone, luteinizing hormone, insulin-like growth factor-1, growth hormone, testosterone (men), prolactin, thyroid-stimulating hormone, and free T(4).

RESULTS

Endocrine remission occurred in 144 of 199 patients with a functioning adenoma. Tumor control rate was 89%. Eighty patients experienced at least 1 axis of new-onset SRS-induced hypopituitarism. The new hypopituitarism rate was 30% based on endocrine follow-up ranging from 6 to 150 months; the actuarial rate of new pituitary hormone deficiency was 31.5% at 5 years after SRS. On univariate and multivariate analyses, variables regarding the increased risk of hypopituitarism included suprasellar extension and higher radiation dose to the tumor margin; there were no correlations among tumor volume, prior transsphenoidal adenomectomy, prior radiation therapy, and age at SRS.

CONCLUSION

SRS provides an effective and safe treatment option for patients with a pituitary adenoma. Higher margin radiation dose to the adenoma and suprasellar extension were 2 independent predictors of SRS-induced hypopituitarism.

Radiotherapy-induced hypopituitarism: a review

Hypopituitarism is a disorder caused by impaired hormonal secretions from the hypothalamic-pituitary axis. Radiotherapy is the most common cause of iatrogenic hypopituitarism. The hypothalamic-pituitary axis inadvertently gets irradiated in patients receiving prophylactic cranial radiotherapy for leukemia, total body irradiation and radiotherapy for intracranial, base skull, sinonasal and nasopharyngeal tumors. Radiation-induced hypopituitarism (RIH) is insidious, progressive and largely nonreversible. Mostly, RIH involves one hypothalamic-pituitary axis; however, multiple hormonal axes deficiency starts developing at higher doses. Although the clinical effects of the hypopituitarism are more profound in children and young adults, its implications in older adults are being increasingly recognized. The risk continues to persist or increase up to 10 years following radiation exposure. The clinical management of hypopituitarism is challenging both for the patients and healthcare providers. Here we have reviewed the scale of the problem, the risk factors and the management of RIH.

Treatment of Cushing disease: overview and recent findings

Endogenous Cushing syndrome is an endocrine disease caused by excessive secretion of adrenocorticotropin hormone in approximately 80% of cases, usually by a pituitary corticotroph adenoma (Cushing disease [CD]). It is a heterogeneous disorder requiring a multidisciplinary and individualized approach to patient management. The goals of treatment of CD include the reversal of clinical features, the normalization of biochemical changes with minimal morbidity, and long-term control without recurrence. Generally, the treatment of choice is the surgical removal of the pituitary tumor by transsphenoidal approach, performed by an experienced surgeon. Considering the high recurrence rate, other treatments should be considered. Second-line treatments include more radical surgery, radiation therapy, medical therapy, and bilateral adrenalectomy. Drug treatment has been targeted at the hypothalamic or pituitary level, at the adrenal gland, and also at the glucocorticoid receptor level. Frequently, medical therapy is performed before surgery to reduce the complications of the procedure, reducing the effects of severe hypercortisolism. Commonly, in patients in whom surgery has failed, medical management is often essential to reduce or normalize the hypercortisolemia, and should be attempted before bilateral adrenalectomy is considered. Medical therapy can be also useful in patients with CD while waiting for pituitary radiotherapy to take effect, which can take up to 10 years or more. So far, results of medical treatment of CD have not been particularly relevant; however, newer tools promise to change this scenario. The aim of this review is to analyze the results and experiences with old and new medical treatments of CD and to reevaluate medical therapies for complications of CD and hypopituitarism in patients with cured CD.

Radiotherapy for pituitary adenomas

This article describes the technical aspects and the clinical results of conventional radiotherapy and modern stereotactic radiotherapy for pituitary adenomas. Systematic review of the published literature provides a factual basis for the comparison and the selection of appropriate radiation technique in patients who have secreting and nonfunctioning pituitary adenomas not cured with surgery and medical therapy.

Adrenocortical hypertension

Primary aldosteronism, congenital adrenal hyperplasia, Cushing's syndrome, glucocorticoid-remediable aldosteronism, and corticotropin-dependent forms of adrenal pathology can cause hypertension by excessive production of adrenocortical hormones. Although traditional biochemical assays continue to be used, genetic testing has simplified the diagnosis of glucocorticoid-remediable aldosteronism. Also new interventional radiologic approaches for the diagnosis and treatment of corticotropin-dependent forms of Cushing's syndrome are available. Medical and surgical approaches, however, still remain viable options for treatment.

Characteristics of adult patients with growth hormone deficiency who underwent neurosurgery for functioning and non-functioning pituitary adenomas and craniopharyngiomas

The aim of the present study was to evaluate the characteristics of GH deficiency (GHD) in adult patients after neurosurgery for pituitary adenomas and craniopharingiomas. One hundred and one GHD patients, (42 F/59 M), aged 47.58+/-14.4 yr (mean+/-SD; range 21-78), body mass index (BMI) 28.6+/-0.6, with a history of adult-onset hypothalamic-pituitary disease, were recruited for the study. The whole group included: 45 non-functioning pituitary adenomas, 23 craniopharyngiomas, 16 PRLomas, 8 GHomas, 7 ACTHomas and 2 FSHomas; in particular 51 were macroadenomas and 27 microadenomas. At study entry, GHD diagnosis was carried out by assessing GH secretion after GHRH+arginine. All patients were submitted to the study at least 12 months after neurosurgery and, where needed, subjects were replaced with an appropriate treatment. GHD was mild in 3/101 (3%) and severe in 98/101 patients (97%). Other hormone deficiencies associated with GHD were considered: TSH, ACTH, FSH/LH, ADH. The distribution of peak GH among all patients, according to the type of disease before neurosurgery, showed that patients with Cushing disease were characterized by the presence of higher peak GH. According to the number of additional hormone deficits, the distribution of peak GH among all patients was as follows: GHD was isolated in 4/101 subjects (4%; group A), while it was associated with 1 (14/101, 14%; group B), 2 (22/101, 22%; group C), 3 (44/101, 43%; group D) and 4 hormone deficits (17/101, 16%; group E). GHD was severe in all patients in the panhypopituitaric group. Total IGF-I plasma levels in the whole group of GHD patients were 95.2+/-4.2 microg/l. In all groups of patients IGF-I was lower in subjects with severe GHD than in those with mild GHD (93.6+/-4.1 vs 148.6+/-33.6 microg/l, p<0.03). In particular, according to the type of disease presented before neurosurgery, patients with Cushing disease were characterized by the presence of higher IGF-I plasma levels compared to the other. According to the number of additional deficits, the distribution of IGF-I plasma levels was characterized by higher values when GHD was isolated than when it was associated with multiple hormone deficiencies. IGF-I plasma levels were positively associated to peak GH during GHRH+arginine (r=0.4, p<0.0005). We conclude that patients after neurosurgery approach for sellar and parasellar neoplasia, within an appropriate clinical context, and both the presence of additional pituitary hormone deficiency and low levels of IGF-I can be considered a clear GHD condition, and therefore do not require provocative tests evaluating GH secretion.

Adrenocortical hypertension

Primary aldosteronism, congenital adrenal hyperplasia, Cushing's syndrome, glucocorticoid-remediable aldosteronism, and corticotropin-dependent forms of adrenal pathology can cause hypertension by excessive production of adrenocortical hormones. Although traditional biochemical assays continue to be used, genetic testing has simplified the diagnosis of glucocorticoid-remediable aldosteronism. Also, new interventional radiologic approaches for the diagnosis and treatment of corticotropin-dependent forms of Cushing's syndrome are available. Medical and surgical approaches, however, still remain viable options for treatment.

Stereotactic radiosurgery for Cushing disease

The most common cause of Cushing syndrome is Cushing disease, in which hypercortisolism is produced by a functional adrenocorticotropic hormone–producing adenoma of the anterior pituitary gland. The common therapies available include microsurgical resection, conventional fractionated radiotherapy, and stereotactic radiosurgery (SRS). In this article the authors review the indications, results, and complications associated with SRS in the treatment of Cushing disease.

In as many as 90% of patients SRS results in disease remission, which is defined as a normal 24-hour urinary free cortisol level and a normal or subnormal morning serum cortisol level. Although in most patients who are subsequently cured a marked decrease in the serum cortisol level is demonstrated within 3 months after treatment, a biochemical cure may be delayed up to 3 years in some cases. Complications following SRS for pituitary adenomas are uncommon, particularly in patients with microadenomas, which are most commonly seen in Cushing disease. The most common complication is hypopituitarism, which occurs in up to 50% of patients with a mean latency period of 5 years. Radiation-induced optic neuropathy has been reported in less than 2% of cases and induction of a secondary neoplasm in less than 1% of cases.

For patients with Cushing disease, the rate of endocrinological cure following SRS appears to be similar to that attained using microsurgical resection. In contrast to surgery, SRS has the benefit of being noninvasive and associated with a very low incidence of diabetes insipidus, although hypopituitarism may be more common with SRS. With continued follow-up patient reviews and additional experience with SRS, it may become possible to make more definitive statements regarding SRS as the initial treatment for patients with Cushing disease.