Gamma knife radiosurgery in the treatment of Cushing disease: long-term results

Early versus late Gamma Knife radiosurgery for Cushing's disease after prior resection: results of an international, multicenter study

OBJECTIVE

The optimal time to perform stereotactic radiosurgery after incomplete resection of adrenocorticotropic hormone (ACTH)-producing pituitary adenoma in patients with Cushing's disease (CD) remains unclear. In patients with persistent CD after resection of ACTH-producing pituitary adenoma, the authors evaluated the association of the interval between resection and Gamma Knife radiosurgery (GKRS) with outcomes.

METHODS

Pooled data from 10 institutions participating in the International Radiosurgery Research Foundation were used in this study.

RESULTS

Data from 255 patients with a mean follow-up of 65.59 ± 49.01 months (mean ± SD) were analyzed. Seventy-seven patients (30%) underwent GKRS within 3 months; 46 (18%) from 4 to 6 months; 34 (13%) from 7 to 12 months; and 98 (38%) at > 12 months after the resection. Actuarial endocrine remission rates were higher in patients who underwent GKRS ≤ 3 months than when treatment was > 3 months after the resection (78% and 65%, respectively; p = 0.017). Endocrine remission rates were lower in patients who underwent GKRS at > 12 months versus ≤ 12 months after the resection (57% vs 76%, respectively; p = 0.006). In multivariate Cox regression analyses adjusted for clinical and treatment characteristics, early GKRS was associated with increased probability of endocrine remission (hazard ratio [HR] 1.518, 95% CI 1.039-2.218; p = 0.031), whereas late GKRS (HR 0.641, 95% CI 0.448-0.919; p = 0.015) was associated with reduced probability of endocrine remission. The incidence of some degree of new pituitary deficiency (p = 0.922), new visual deficits (p = 0.740), and other cranial nerve deficits (p = 0.610) was not significantly related to time from resection to GKRS.

CONCLUSIONS

Early GKRS is associated with an improved endocrine remission rate, whereas later GKRS is associated with a lower rate of endocrine remission after pituitary adenoma resection. Early GKRS should be considered for patients with CD after incomplete pituitary adenoma resection.

Management of Cushing's Disease After Failed Surgery - A Review

Selective transsphenoidal adenomectomy is generally recommended for initial treatment of Cushing's disease (CD) because it achieves a high (70-85%) rate of remission. However, if initial surgery is not successful, the approach to persistent or recurrent CD is more complex. Because residual or recurrent adenoma is typically found at the site of the original adenoma, repeat transsphenoidal surgery is recommended including selective adenomectomy, hemihypophysectomy or total hypophysectomy. If repeat pituitary surgery does not achieve remission, then possible adjuvant therapies include radiosurgery or stereotactic radiotherapy, bilateral adrenalectomy, and/or medical therapy. In all cases of persistent or recurrent CD, successful treatment requires close collaboration of endocrinologists, radiation oncologists and neurosurgeons.

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.

Gamma knife radiosurgery for Cushing's disease and Nelson's syndrome

PURPOSE

This paper presents our 18 years of experience in treating ACTH secreting adenomas (Cushing's disease and Nelson's syndrome) using the Leksell gamma knife (LGK) irradiation.

METHODS

Twenty-six patients with Cushing's disease were followed-up after LGK irradiation for 48-216 months (median 78 months). Seventeen patients had undergone previous surgery, in nine patients LGK irradiation was the primary therapy. Furthermore, 14 patients with Nelson's syndrome were followed-up for 30-204 months (median 144 months).

RESULTS

LGK treatment resulted in hormonal normalization in 80.7 % of patients with Cushing's disease. Time to normalization was 6-54 months (median 30 months). The volume of the adenoma decreased in 92.3% (in 30.7% disappeared completely). There was no recurrence of the disease. In all 14 patients with Nelson's syndrome ACTH levels decreased (in two patients fully normalized) their ACTH levels. When checked up 5-10 years after irradiation regrowth of the adenoma was only detected in one patient (9.1%), in 27.3% adenoma volume remained unchanged, in 45.4% adenoma volume decreased and in 18.2% adenoma completely disappeared. Hypopituitarism did not develop in any patient where the critical dose to the pituitary and distal infundibulum was respected.

CONCLUSION

LGK radiation represents an effective and well-tolerated option for the treatment of patients with Cushing's disease after unsuccessful surgery and may be valuable even as a primary treatment in patients who are not suitable for, or refuse, surgery. In the case of Nelson's syndrome it is possible to impede tumorous growth and control the size of the adenoma in almost all patients.

Stereotactic radiotherapy and radiosurgery for non-functioning and secreting pituitary adenomas

Radiotherapy (RT) is frequently employed in patients with residual or recurrent pituitary adenoma with excellent rates of tumor control and remission of hormonal hypersecretion. Advances in RT have improved with the use of stereotactic techniques either as fractionated stereotactic radiotherapy (FSRT) or stereotactic radiosurgery (SRS), all aiming to improve the dose distribution to the tumor while reducing the amount of normal brain receiving significant doses of radiation. We provide an overview of the recent published literature on the long-term efficacy and adverse effects of stereotactic irradiation in nonfunctioning and secreting pituitary adenomas. Both techniques are associated with excellent clinical outcomes; however, advantages and drawbacks of each of these techniques in terms of local control, hormonal excess normalization, and radiation-induced toxicity remain a matter of debate. In clinical practice, single-fraction SRS may represent a convenient approach to patients with small and medium-sized pituitary adenoma away at least 2 mm from the optic chiasm, whereas FSRT is preferred over SRS for lesions >2.5-3 cm in size and/or involving the anterior optic pathway.

Cranial stereotactic radiosurgery: current status of the initial paradigm shifter

The concept of stereotactic radiosurgery (SRS) was first described by Lars Leksell in 1951. It was proposed as a noninvasive alternative to open neurosurgical approaches to manage a variety of conditions. In the following decades, SRS emerged as a unique discipline involving a collegial partnership among neurosurgeons, radiation oncologists, and medical physicists. SRS relies on the precisely guided delivery of high-dose ionizing radiation to an intracranial target. The focused convergence of multiple beams yields a potent therapeutic effect on the target and a steep dose fall-off to surrounding structures, thereby minimizing the risk of collateral damage. SRS is typically administered in a single session but can be given in as many as five sessions or fractions. By providing an ablative effect noninvasively, SRS has altered the treatment paradigms for benign and malignant intracranial tumors, functional disorders, and vascular malformations. Literature on extensive intracranial radiosurgery has unequivocally demonstrated the favorable benefit-to-risk profile that SRS affords for appropriately selected patients. In a departure from conventional radiotherapeutic strategies, radiosurgical principles have recently been extended to extracranial indications such as lung, spine, and liver tumors. The paradigm shift resulting from radiosurgery continues to alter the landscape of related fields.

Silent corticotroph adenomas after stereotactic radiosurgery: a case-control study

PURPOSE

To investigate the safety and effectiveness of stereotactic radiosurgery (SRS) in patients with a silent corticotroph adenoma (SCA) compared with patients with other subtypes of non-adrenocorticotropic hormone staining nonfunctioning pituitary adenoma (NFA).

METHODS AND MATERIALS

The clinical features and outcomes of 104 NFA patients treated with SRS in our center between September 1994 and August 2012 were evaluated. Among them, 34 consecutive patients with a confirmatory SCA were identified. A control group of 70 patients with other subtypes of NFA were selected for review based on comparable baseline features, including sex, age at the time of SRS, tumor size, margin radiation dose to the tumor, and duration of follow-up.

RESULTS

The median follow-up after SRS was 56 months (range, 6-200 months). No patients with an SCA developed Cushing disease during the follow-up. Tumor control was achieved in 21 of 34 patients (62%) in the SCA group, compared with 65 of 70 patients (93%) in the NFA group. The median progression-free survival (PFS) was 58 months in the SCA group. The actuarial PFS was 73%, 46%, and 31% in the SCA group and was 94%, 87%, and 87% in the NFA group at 3, 5, and 8 years, respectively. Silent corticotroph adenomas treated with a dose of ≥17 Gy exhibited improved PFS. New-onset loss of pituitary function developed in 10 patients (29%) in the SCA group, whereas it occurred in 18 patients (26%) in the NFA group. Eight patients (24%) in the SCA group experienced worsening of a visual field deficit or visual acuity attributed to the tumor progression, as did 6 patients (9%) in the NFA group.

CONCLUSION

Silent corticotroph adenomas exhibited a more aggressive course with a higher progression rate than other subtypes of NFAs. Stereotactic radiosurgery is an important adjuvant treatment for control of tumor growth. Increased radiation dose may lead to improved tumor control in SCA patients.

Initial Gamma Knife radiosurgery for nonfunctioning pituitary adenomas

Object

Nonfunctioning pituitary adenomas (NFAs) are the most common type of pituitary adenoma and, when symptomatic, typically require surgical removal as an initial means of management. Gamma Knife radiosurgery (GKRS) is an alternative therapeutic strategy for patients whose comorbidities substantially increase the risks of resection. In this report, the authors evaluated the efficacy and safety of initial GKRS for NFAs.

Methods

An international group of three academic Gamma Knife centers retrospectively reviewed outcome data in 569 patients with NFAs.

Results

Forty-one patients (7.2%) underwent GKRS as primary management for their NFAs because of an advanced age, multiple comorbidities, or patient preference. The median age at the time of radiosurgery was 69 years. Thirty-seven percent of the patients had hypopituitarism before GKRS. Patients received a median tumor margin dose of 12 Gy (range 6.2–25.0 Gy) at a median isodose of 50%. The overall tumor control rate was 92.7%, and the actuarial tumor control rate was 94% and 85% at 5 and 10 years postradiosurgery, respectively. Three patients with tumor growth or symptom progression underwent resection at 3, 3, and 96 months after GKRS, respectively. New or worsened hypopituitarism developed in 10 patients (24%) at a median interval of 37 months after GKRS. One patient suffered new-onset cranial nerve palsy. No other radiosurgical complications were noted. Delayed hypopituitarism was observed more often in patients who had received a tumor margin dose > 18 Gy (p = 0.038) and a maximum dose > 36 Gy (p = 0.025).

Conclusions

In this study, GKRS resulted in long-term control of NFAs in 85% of patients at 10 years. This experience suggests that GKRS provides long-term tumor control with an acceptable risk profile. This approach may be especially valuable in older patients, those with multiple comorbidities, and those who have endocrine-inactive tumors without visual compromise due to mass effect of the adenoma.

Encouraging efficacy of modern conformal fractionated radiotherapy in patients with uncured Cushing's disease

The objective of this study was to assess the efficacy of modern conformal fractionated radiotherapy (RT) in patients with uncured Cushing's disease (CD) after failed transsphenoidal surgery (TSS). In this retrospective analysis, we reviewed records of patients with CD who received modern conformal fractionated RT between 2001 and 2010. Records were evaluated for frequency and interval of remission post RT. The change in the tumour size, endocrine insufficiencies and complications developing post RT were noted. Remission was defined as 2 mg Low dose dexamethasone suppressed cortisol of <50 nmol/l. During the study period of 10 years, a total of 24 patients (mean age: 27.9, range: 21-48 years) underwent pituitary RT for CD. Out of these, long term follow up was available for 22 patients and 20 patients (15F/5M, 12 microadenomas/8 macroadenomas) were included for final analysis. All the patients received modern conformal fractionated external beam RT (45 Gy in 25 fractions) with the median follow up of 37.5 months (range 12-144). Fifteen patients (10 microadenomas/5 macroadenomas) underwent remission after a median follow up period of 20 months. None of the patients had recurrence. Post RT, new onset endocrine deficiencies were seen in 8 (40 %) patients. Modern conformal fractionated external beam radiotherapy is an effective modality for treatment of adult patients with CD after failed TSS.

The burden of Cushing's disease: clinical and health-related quality of life aspects

OBJECTIVE

Cushing's disease (CD) is a rare endocrine disorder characterized by excess secretion of ACTH due to a pituitary adenoma. Current treatment options are limited and may pose additional risks. A literature review was conducted to assess the holistic burden of CD.

DESIGN

Studies published in English were evaluated to address questions regarding the epidemiology of CD, time to diagnosis, health-related quality of life (HRQoL), treatment outcomes, mortality, prevalence of comorbidities at diagnosis, and reversibility of comorbidities following the treatment.

METHODS

a two-stage literature search was performed in Medline, EMBASE, and Science Citation Index, using keywords related to the epidemiology, treatment, and outcomes of CD: i) articles published from 2000 to 2012 were identified and ii) an additional hand search (all years) was conducted on the basis of bibliography of identified articles.

RESULTS

At the time of diagnosis, 58-85% of patients have hypertension, 32-41% are obese, 20-47% have diabetes mellitus, 50-81% have major depression, 31-50% have osteoporosis, and 38-71% have dyslipidemia. Remission rates following transsphenoidal surgery (TSS) are high when performed by expert pituitary surgeons (rates of 65-90%), but the potential for relapse remains (rates of 5-36%). Although some complications can be partially reversed, time to reversal can take years. The HRQoL of patients with CD also remains severely compromised after remission.

CONCLUSIONS

These findings highlight the significant burden associated with CD. As current treatment options may not fully reverse the burden of chronic hypercortisolism, there is a need for both improved diagnostic tools to reduce the time to diagnosis and effective therapy, particularly a targeted medical therapy.

Excess mortality for patients with residual disease following resection of pituitary adenomas

The importance of achieving tumor control in pituitary adenoma surgery is not entirely established. This manuscript reviews the literature linking residual pituitary tumor and hormonal hypersecretion to increases in long term mortality. When possible, we utilized meta-analysis methods to estimate a pooled standardized mortality ratio (SMR), which relates the risk of mortality for a cohort of patients compared to a similar age and gender matched cohort in the general population, for patients with endocrinologic evidence of residual disease. When this was not possible, we review the existing literature in the results and discussion section of this review. We identified 10 articles regarding acromegaly and three articles regarding Cushing's disease which presented SMR data for adult patients undergoing transphenoidal surgery with data divided into subgroups based on post-operative growth hormone levels. Using growth hormone levels of 2.5 μg/l as a cutoff, the mortality rate ratio was 1.83 (95% CI = 1.03-3.24) for patients with persistent acromegaly. Similarly, patients with persistent Cushing's disease experienced a marked increase in mortality rate ratio compared to those experiencing initial cure (mortality rate ratio = 3.25 (95% CI = 1.54-6.84). For other tumor subtypes, (i.e. Endocrine inactive adenomas, Prolactinomas, and TSH secreting tumors) there were not enough studies identified to allow for rigorous statistical analysis. There is an increasing body of data suggesting that treatment refractory acromegaly and Cushing's disease puts patients at risk for early mortality, suggesting that aggressive efforts to normalize hormone levels in these patients are justified.

Management of Cushing disease

Cushing disease is caused by a corticotroph tumor of the pituitary gland. Patients with Cushing disease are usually treated with transsphenoidal surgery, as this approach leads to remission in 70-90% of cases and is associated with low morbidity when performed by experienced pituitary gland surgeons. Nonetheless, among patients in postoperative remission, the risk of recurrence of Cushing disease could reach 20-25% at 10 years after surgery. Patients with persistent or recurrent Cushing disease might, therefore, benefit from a second pituitary operation (which leads to remission in 50-70% of cases), radiation therapy to the pituitary gland or bilateral adrenalectomy. Remission after radiation therapy occurs in ∼85% of patients with Cushing disease after a considerable latency period. Interim medical therapy is generally advisable after patients receive radiation therapy because of the long latency period. Bilateral adrenalectomy might be considered in patients who do not improve following transsphenoidal surgery, particularly patients who are very ill and require rapid control of hypercortisolism, or those wishing to avoid the risk of hypopituitarism associated with radiation therapy. Adrenalectomized patients require lifelong adrenal hormone replacement and are at risk of Nelson syndrome. The development of medical therapies with improved efficacy might influence the management of this challenging condition.

Radiation therapy and stereotactic radiosurgery for the treatment of Cushing's disease: an evidence-based review

PURPOSE OF REVIEW

The indications, efficacy, and safety of radiation therapy and stereotactic radiosurgery for Cushing's disease are evaluated.We queried PubMed using the terms, 'Cushing's disease', 'radiotherapy', and 'radiosurgery', then evaluated each study for the number of patients, method of radiation delivery, type of radiation therapy or radiosurgical device used, treatment parameters (e.g. maximal dose, tumor margin dose), length of follow-up, tumor-control rate, complications, rate of hormone normalization, newly onset loss of pituitary function, and method used to assess endocrine remission.

RECENT FINDINGS

A total of 39 peer-reviewed studies with 731 patients were included. The reported rates of tumor-volume control following radiotherapy and radiosurgery vary considerably from 66-100%. Additionally, the reported rates of endocrine remission vary substantially from 17-100%. The incidence of serious complications following radiosurgery is quite low. Although post-treatment hypopituitarism and disease recurrence were uncommon, they did occur, and this underscores the necessity for long-term follow-up in these patients.

SUMMARY

Radiosurgery and, in the modern era, less commonly, radiation therapy, offer both well tolerated and reasonably effective treatment for recurrent or residual Cushing's adenomas.

Role of stereotactic radiosurgery in the management of pituitary adenomas

Trans-sphenoidal neurosurgery is the gold standard treatment for pituitary adenomas, but it can be contraindicated or ineffective. Stereotactic radiosurgery is a procedure aimed at controlling hormone hypersecretion and tumor size of pituitary adenomas. This Review discusses the long-term efficacy and adverse effects of stereotactic radiosurgery with the Gamma Knife((R)) in secreting and nonsecreting pituitary adenomas. Long-term data confirm the antisecretory efficacy of the procedure (about 50% remission in hypersecreting tumors) but also a previously unknown low risk of recurrence (2-10% of cases). The time to remission is estimated to range from 12 to 60 months. The antitumoral efficacy of this treatment against nonsecreting tumors is observed in about 90% of cases. Hypopituitarism is the main adverse effect, observed in 20-40% of cases. Comparisons with conventional fractionated radiotherapy reveal a lower rate of remission with Gamma Knife((R)) radiosurgery, counterbalanced by a more rapid efficacy and a lower rate of hypopituitarism. Short-term follow-up results on stereotactic fractionated radiotherapy suggest a risk of hypopituitarism similar to the one observed with radiosurgery. Therefore, stereotactic radiosurgery is probably still useful to treat some cases of pituitary adenoma, despite the fact that antisecretory drugs, particularly for acromegaly and prolactinomas, are becoming more effective and are well tolerated, thus increasing the probability of success with nonsurgical therapy.

Long-term results of stereotactic radiosurgery in secretory pituitary adenomas

CONTEXT

To date, no study reported long-term follow-up results of gamma knife stereotactic radiosurgery (SR).

OBJECTIVE

The aim of the study was to determine long-term efficacy and adverse effects of SR in secreting pituitary adenomas.

DESIGN

We conducted a retrospective study of patients treated by SR in the center of Marseille, France, with a follow-up of at least 60 months.

PATIENTS

A total of 76 patients were treated by SR for acromegaly (n = 43), Cushing's disease (CD; n = 18), or prolactinoma (n = 15) as a primary (n = 27) or adjunctive postsurgical treatment (n = 49).

MAIN OUTCOME MEASURES

After withdrawal of antisecretory drugs, patients were considered in remission if they had mean GH levels below 2 ng/ml and normal IGF-I (acromegaly), normal 24-h urinary free cortisol, and cortisol less than 50 nmol/liter after low-dose dexamethasone test (CD) or two consecutive normal samplings of prolactin levels (prolactinoma).

RESULTS

After a mean follow-up of 96 months, 44.7% of the patients were in remission. Mean time to remission was 42.6 months. Twelve patients presented late remission at least 48 months after SR. Two patients with CD presented late recurrence 72 and 96 months after SR. Forty percent of patients treated primarily with SR were in remission. Target volume and initial hormone levels were significant predictive factors of remission in univariate analysis. Radiation-induced hypopituitarism was observed in 23% patients; in half of them, hypopituitarism was observed after a mean time of 48 to 96 months. Twenty-four patients were followed for more than 120 months; rates of remission and hypopituitarism were similar to the whole cohort.

CONCLUSIONS

SR is an effective and safe primary or adjunctive treatment in selected patients with secreting pituitary adenomas.

Modern techniques for pituitary radiotherapy

Radiotherapy (RT) remains an effective treatment for residual or recurrent pituitary adenomas with excellent rates of tumour control and normalisation of excess hormone secretion. The main late toxicity is hypopituitarism: other side effects are rare. We discuss technical developments in the delivery of radiotherapy (stereotactic conformal radiotherapy (SCRT) and stereotactic radiosurgery (SRS)), all aiming to reduce the amount of normal brain receiving significant doses of radiation. We provide a comprehensive review of published data on outcome of conventional fractionated radiotherapy and modern RT techniques. SCRT is a suitable treatment technique for all sizes of pituitary adenoma and efficacy is comparable to conventional RT; the lack of long term follow up means that currently there is no information on potential reduction in the incidence of late radiation induced toxicity. Single fraction SRS can only be safely delivered to small tumours away from critical structures. There is no evidence that it produces faster decline of elevated hormone levels than fractionated treatment and is not associated with lesser morbidity.

An approach to the management of patients with residual Cushing's disease

The evaluation and management of patients with residual Cushing’s disease is one of the more complex issues facing neurosurgeons and neuroendocrinologists in clinical practice. There is considerable controversy over several relevant issues such as the timing of the assessment of whether a patient is in remission, what biochemical parameters define remission, the most appropriate course of action to take after residual disease has been defined, etc. As a consequence of the controversies, treating physicians develop notions and fall into certain practice patterns based on evidence of varying levels, their anecdotal experiences, and information gleaned from scientific meetings. This practice pattern, we believe, constitutes the “art of medicine.” We conducted a PubMed literature search to identify manuscripts containing data relevant to Cushing’s disease, outcomes of various therapeutic modalities, and recurrences. Reference lists were used to identify additional relevant manuscripts. We focused our review on manuscripts that included reasonably large series of patients, those reflecting the experience of pituitary centers and physicians recognized as experts in the field, and those papers felt to represent seminal contributions to the literature. Furthermore, trends in the evaluation and management of relevant patients have been incorporated by the senior author who has seen and evaluated over 750 patients with documented Cushing’s syndrome over the past 18 years in clinical practice. An analysis of current evidence indicated that, despite advances in neurosurgical techniques and recent developments in adjuvant therapies, patients with residual Cushing’s disease present significant management challenges to treating physicians. In this era, however, it is indeed possible to gain control of the hypercortisolism in most patients. Despite the wide variability in research methodology designed to collect relevant data, a step-wise approach to the management of these patients can be achieved. A logical step-wise approach to the evaluation of postoperative patients with Cushing’s disease is essential. Patients with residual disease require the development of an individualized plan of management that takes into account numerous factors pertaining to status of disease, the experience of treating physicians, and available therapeutic modalities.

Stereotactic radiosurgery for pituitary adenomas: a comprehensive review of indications, techniques and long-term results using the Gamma Knife

OBJECT

This study reviews the long-term clinical results of stereotactic radiosurgery in the treatment of pituitary adenoma patients.

METHODS

We reviewed the outcomes of 298 patients who underwent Gamma Knife radiosurgery for recurrent or residual pituitary adenomas. These results are compared to other contemporary radiosurgical series.

RESULTS

Pituitary tumors are well-suited for radiosurgery, since radiation can be focused on a well circumscribed region, while adjacent neural structures in the suprasellar and parasellar regions are spared. The overall rate of volume reduction following stereotactic radiosurgery is 85% for non-secretory adenomas that are followed for more than 1-year. The rates of hormonal normalization in patients with hypersecretory adenomas can vary considerably, and tends to be higher in patients with Cushing's Disease and acromegaly (remission rate of approximately 53% and 54%, respectively) when compared with patients who have prolactinomas (24% remission) and Nelson's syndrome (29%) remission. Advances in dose delivery and modulation of adenoma cells at the time of radiosurgery may further improve results.

CONCLUSIONS

Although the effectiveness of radiosurgery varies considerably depending on the adenoma histopathology, volume, and radiation dose, most studies indicate that radiosurgery when combined with microsurgery is effective in controlling pituitary adenoma growth and hormone hypersecretion. Long-term follow-up is essential to determine the rate of endocrinopathy, visual dysfunction, hormonal recurrence, and adenoma volume control.

Treatment of malignant tumors of the skull base with multi-session radiosurgery

OBJECTIVE

Malignant tumors that involve the skull base pose significant challenges to the clinician because of the proximity of critical neurovascular structures and limited effectiveness of surgical resection without major morbidity. The purpose of this study was to evaluate the efficacy and safety of multi-session radiosurgery in patients with malignancies of the skull base.

METHODS

Clinical and radiographic data for 37 patients treated with image-guided, multi-session radiosurgery between January 2002 and December 2007 were reviewed retrospectively. Lesions were classified according to involvement with the bones of the base of the skull and proximity to the cranial nerves.

RESULTS

Our cohort consisted of 37 patients. Six patients with follow-up periods less than four weeks were eliminated from statistical consideration, thus leaving the data from 31 patients to be analyzed. The median follow-up was 37 weeks. Ten patients (32%) were alive at the end of the follow-up period. At last follow-up, or the time of death from systemic disease, tumor regression or stable local disease was observed in 23 lesions, representing an overall tumor control rate of 74%. For the remainder of lesions, the median time to progression was 24 weeks. The median progression-free survival was 230 weeks. The median overall survival was 39 weeks. In the absence of tumor progression, there were no cranial nerve, brainstem or vascular complications referable specifically to CyberKnife radiosurgery.

CONCLUSION

Our experience suggests that multi-session radiosurgery for the treatment of malignant skull base tumors is comparable to other radiosurgical techniques in progression-free survival, local tumor control, and adverse effects.

HYPOFRACTIONATED CYBERKNIFE RADIOSURGERY FOR PERICHIASMATIC PITUITARY ADENOMAS

OBJECTIVE

Radiation therapy is recommended for pituitary tumors that are refractory to surgical and medical therapies. The efficacy of single-fraction radiosurgery is established for these lesions, but lesions within 3 mm of the optic pathway cannot be safely treated with doses higher than 8 to 10 Gy. We hypothesized that the optic nerve will tolerate 5 consecutive daily radiosurgery fractions of 500 cGy with effective tumor control.

METHODS

We reviewed our first 20 patients with recurrent or residual pituitary adenomas within 3 mm of the optic chiasm treated with the CyberKnife radiosurgery system (Accuray, Inc., Sunnyvale, CA). Tumors were treated with a mean coverage of 97 ± 2.2% (range, 89.8–99.7%), a mean conformity index of 1.3 ± 0.2 (range, 1.1–1.6), and a mean treatment isodose line of 74.5 ± 6.6% (range, 60–86%). The primary end point was an interim analysis of visual preservation, and secondary end points were radiographic and endocrinological tumor control.

RESULTS

The mean follow-up period for visual field testing was 26.6 ± 10.5 months (range, 10.6–41 months). The vision of all 14 patients with intact preoperative vision remained intact. Of the 5 patients with impaired vision, 2 remained stable, and 3 improved. No patient's vision deteriorated. The mean radiographic follow-up was 29.3 ± 8.6 months (range, 10.2–40.5 months). On magnetic resonance imaging, 12 tumors were stable, 8 were smaller, and none enlarged.

CONCLUSION

This preliminary study establishes that the optic nerve and chiasm tolerate CyberKnife hypofractionated radiosurgery of 5 × 500 cGy to perichiasmatic pituitary adenomas. Early data suggest that this dosing paradigm may achieve satisfactory radiographic and endocrinological tumor control for these challenging lesions, but longer follow-up is necessary to confirm these results.

Management of Cushing's disease: outcome in patients with microadenoma detected on pituitary magnetic resonance imaging

OBJECT

Outcomes of therapy for Cushing's disease (CD) vary depending on different aspects of presentation and diagnostic studies. The authors designed this study to verify the remission rate and outcomes after transsphenoidal surgery (TSS) for patients with CD who had positive findings on MR imaging.

METHODS

Patients who had presented with CD at the University of Virginia for initial treatment between July 1992 and December 2005 were retrospectively reviewed. The patients included in the study were considered to be optimal surgical candidates, defined as an adult (>18 years of age) with classic clinical features of CD, laboratory studies confirming a central (pituitary/hypothalamic) adrenocorticotropic hormone-dependent source of disease, and an MR imaging study revealing a microadenoma in the sella turcica.

RESULTS

A total of 167 patients fulfilled the criteria. Thirty were men (18%) and 137 were women (82%). The mean age was 42.3 years (range 18.2-77 years). All patients underwent TSS. Surgical remission was achieved in 148 patients (88.6%), which was correlated with the surgeon's intraoperative identification of an adenoma (p=0.03). Histopathological confirmation of an adrenocorticotropic hormone-secreting adenoma strongly correlated with remission (p=0.0001). Three patients (1.8%) had postoperative cerebrospinal fluid leaks, and 1 patient had meningitis. Transient diabetes insipidus was diagnosed and treated in 10 patients (6%), whereas permanent diabetes insipidus occurred in 8 patients (4.8%). Panhypopituitarism followed the surgery in 14 patients (8.3%), 13 of whom underwent total hypophysectomy (9 initially and 4 with early reoperations), and in 1 of 10 patients who underwent subtotal hypophysectomy. Nineteen patients (12.8%) who were initially in remission developed recurrent CD after an average of 50 months. The mean follow-up for the 167 patients was 39 months (range 6-157 months). Gamma Knife surgery was the most common modality of radiotherapy used to treat 31 patients (18.5%) who did not achieve remission or later presented with recurrent disease. Bilateral adrenalectomies were performed in 10 patients in the series (6%), 2 of whom developed Nelson's syndrome. The overall posttreatment remission rate was 95.8%.

CONCLUSIONS

Even in patients with ideal diagnostic criteria of CD, there remain a significant number of cases in which TSS alone is not adequate to assure long-lasting remission. A multidisciplinary approach is essential to the achievement of satisfactory overall remission rates.

[Radiosurgery for pituitary adenomas]

Pituitary adenomas represent nearly 15% of all intracranial tumors. Multimodal treatment includes microsurgery, medical management and radiotherapy. Microsurgery is the primary recommendation for nonfunctioning and most of functioning adenomas, except for prolactinomas that are usually managed with dopamine agonist drugs. However, about 30% of patients require additional treatment after microsurgery for recurrent or residual tumors. In these cases, fractionated radiation therapy has been the traditional treatment. More recently, radiosurgery has been established as a treatment option. Radiosurgery allows the delivery of prescribed dose with high precision strictly to the target and spares the surrounding tissues. Therefore, the risks of hypopituitarism, visual damage and vasculopathy are significantly lower. Furthermore, the latency of the radiation response after radiosurgery is substantially shorter than that of fractionated radiotherapy. The goal of this review is to define the efficacy, safety and role of radiosurgery for treatment of pituitary adenomas and to present the preliminary results of our institution.

Role of stereotactic radiosurgery and fractionated stereotactic radiotherapy in pediatric brain tumors

Brain tumors are the most common solid tumor in childhood. Surgery and/or fractionated radiotherapy are conventional treatment modalities. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (FSRT) are advanced radiation therapy techniques that have been frequently used in adults with brain tumors but they are less frequently used in pediatric patients. SRS and FSRT can potentially add to the armamentarium against brain tumors in children. This article will review the role of SRS and FSRT in the management of pediatric brain tumors.

Nelson syndrome: comprehensive review of pathophysiology, diagnosis, and management

Nelson syndrome (NS) is a rare clinical manifestation of an enlarging pituitary adenoma that can occur following bilateral adrenal gland removal performed for the treatment of Cushing disease. It is characterized by excess adreno-corticotropin secretion and hyperpigmentation of the skin and mucus membranes. The authors present a comprehensive review of the pathophysiology, diagnosis, and management of NS. Corticotroph adenomas in NS remain challenging tumors that can lead to significant rates of morbidity and mortality. A better understanding of the natural history of NS, advances in neurophysiology and neuroimaging, and growing experience with surgical intervention and radiation have expanded the repertoire of treatments. Currently available treatments include surgical, radiation, and medical therapy. Although the primary treatment for each tumor type may vary, it is important to consider all of the available options and select the one that is most appropriate for the individual case, particularly in cases of lesions resistant to intervention.

Stereotactic radiosurgery for Cushing disease: a review

✓ A contemporary review of the use of stereotactic radiosurgery in the treatment of Cushing disease (CD) is presented with information drawn from a literature review and from the author's experience. Stereotactic radiosurgery is an effective and safe therapeutic alternative for treating CD in carefully selected cases. Improvements in imaging, dose planning, and general understanding of radiobiology are likely to yield better results in the future.

Radiotherapy and radiosurgery for Cushing's disease

Patients with residual or recurrent Cushing's disease receive external beam radiotherapy (RT) with the aim of achieving long-term tumour control and normalization of elevated hormone levels. Treatment is given either as conventional radiotherapy using conformal techniques or as stereotactic radiotherapy, which is either used as fractionated treatment (SCRT) or as single fraction radiosurgery (SRS). We describe the technical aspects of treatment and report a systematic review of the published literature on the efficacy and toxicity of conventional RT, SCRT and SRS. There are no studies directly comparing the different radiation techniques and the reported results are inevitably of selected patients by investigators with interest in the treatment tested. Nevertheless the review of the published literature suggests better hormone and tumour control rates after fractionated irradiation compared to single fraction radiosurgery. Hypopituitarism represents the most commonly reported late complication of radiotherapy seen after all treatments. Although the incidence of other late effects is low, the risk of radiation injury to normal neural structures is higher with single fraction compared to fractionated treatment. Stereotactic techniques offer more localized irradiation compared with conventional radiotherapy, however longer follow-up is necessary to confirm the potential reduction of long-term radiation toxicity of fractionated SCRT compared to conventional RT. On the basis of the available literature, fractionated conventional and stereotactic radiotherapy offer effective treatment for Cushing's disease not controlled with surgery alone. The lower efficacy and higher toxicity of single fraction treatment suggest that SRS is not the appropriate therapy for the majority of patients with Cushing's disease.

Radiotherapy of pituitary adenomas: state of the art

Pituitary adenomas represent approximately 12% of intracranial tumors. They are defined as tumors that are functional or nonfunctional and invasive or noninvasive. Therapeutic strategies rely on surgery, medical treatment, and radiotherapy depending on histology. Neither the role of external radiotherapy nor the technique to be used are firmly established. Nonfunctioning adenomas must be operated on to relieve the compression. Prolactin-secreting adenomas are first treated with dopamine agonists, and GH-secreting adenomas are first treated by surgery if excising the complete tumor is possible; otherwise medical treatment is started. The first-line treatment of ACTH-secreting adenomas is surgery; however, in many cases, insufficient control of either secretion or tumoral volume leads to consideration of irradiation. Complications of conventional radiotherapy are well known and fractionated stereotactic radiotherapy appears to be as safe as radiosurgery. The volume to irradiate is still difficult to define, and this parameter can influence the technique chosen for treatment. Because the indications of radiotherapy are still debated, irradiation of pituitary adenomas must be decided by the complete team of endocrinologists, neurosurgeons, radiologists and radiotherapists.

Pituitary adenomas treated with gamma knife radiosurgery: volumetric analysis of 100 cases with minimum 3 year follow-up

OBJECTIVE

To analyze pituitary adenoma volume changes after gamma knife radiosurgery (GKRS) in patients with 3 years of follow-up and to investigate factors that might affect these changes.

METHODS

Between January 1997 and March 2004, a total of 1930 patients were treated in the Gamma Knife Unit of the Marmara University Department of Neurosurgery in Istanbul, Turkey. Three hundred sixty of these patients had pituitary adenomas (PAs). This prospectively designed clinical study documents the radiological-volumetric analysis for the first 100 of these patients with PAs who had a minimum of 3 years of follow-up and met the study requirements. Each tumor was assessed with serial magnetic resonance imaging scans after radiosurgery; at each time point, adenoma volume was expressed as a percentage of the tumor's initial volume. Volume changes were investigated relative to margin dose, the cavernous sinus infiltration, and endocrinological type of adenoma.

RESULTS

At the end of the first year after GKRS, the PA volumes had decreased to approximately 90% of the initial volume on average. The corresponding approximate averages for the ends of Years 2 and 3 were 80 and 70% of the initial volume, respectively. At 3 years after GKRS, the PAs in the group with a peripheral dose of less than 17 Gy were reduced to approximately 80% of the initial volume on average. In contrast, the tumors in the patients with marginal doses of 21 to 23 Gy were reduced to approximately 60% of the initial volume at this stage. The adenomas treated with the highest marginal doses (>27 Gy) showed the earliest volume decreases after GKRS (6-9 mo after the procedure). Cavernous sinus noninfiltrating adenomas showed greater volume decreases after GKRS; on average, these masses were reduced to approximately 50% of their initial volume at 3 years. In contrast, the PAs that had infiltrated the cavernous sinus had only dropped to approximately 80% of their initial volume at this stage. The growth hormone-secreting PAs showed the maximum volume decrease with GKRS. On average, these lesions were approximately 60% of their initial volume at the 3-year stage. The nonfunctioning tumors and the prolactin-secreting adenomas showed similar volume changes over time. On average, these tumors had dropped to approximately 75 and 70% of the initial volume, respectively, by 3 years after GKRS.

CONCLUSION

Gamma knife radiosurgery halts the growth of pituitary adenomas. Cavernous sinus extension and margin dose are the most important determinants of adenoma volume after this type of therapy.

Outcomes and management of patients with Cushing's disease without pathological confirmation of tumor resection after transsphenoidal surgery

CONTEXT

Despite the success of transsphenoidal surgery (TSS) for the treatment of Cushing's disease, in a number of cases, an ACTH-staining pituitary adenoma is not identified histologically. The clinical significance of lack of histological confirmation remains unclear.

SETTING

This was a retrospective review of patients treated at the University of Virginia Medical Center.

PATIENTS

Of 490 TSS procedures for Cushing's disease between 1993 and 2004, we identified 111 cases without histological adenoma confirmation.

MAIN OUTCOME MEASURE

Remission and recurrence of Cushing's disease were measured.

RESULTS

Overall, 50% of these patients achieved remission, a figure lower than for our entire series (79%) and for patients with histological confirmation of an ACTH-staining adenoma (88%) (P < 0.001). Patients with a history of two prior TSS achieved remission less often than patients with a history of fewer TSS (P = 0.026). No other factors influenced remission rates. Although the overall recurrence rate (21%, seven of 33 evaluated) was not different from previously published long-term studies, in three of seven cases of recurrence, early recurrences were noted between 2 and 4 months after remission. In patients who did not achieve remission, the most common and effective treatment options were repeat TSS, gamma-knife radiosurgery, and bilateral adrenalectomy.

CONCLUSION

The lower remission rate in patients without histological evidence of an adenoma is most likely a result of a decreased rate of adenoma extirpation. The incidence of early recurrence may be a unique feature of this patient population; patients without histological confirmation of tumor resection therefore require close and consistent monitoring postoperatively.

Gamma Knife surgery for Cushing's disease

Object

In this study the authors address the efficacy and safety of Gamma Knife surgery (GKS) in patients with adrenocorticotropic hormone–secreting pituitary adenomas.

Methods

A review of data collected from a prospective GKS database between January 1990 and March 2005 was performed in patients with Cushing's disease. All but one patient underwent resection for a pituitary tumor, without achieving remission. Successful endocrine outcome after GKS was defined as a normal 24-hour urinary free cortisol (UFC) concentration posttreatment after a minimum of 1 year of follow up. Patient records were also evaluated for changes in tumor volume, development of new hormone deficiencies, visual acuity, cranial nerve neuropathies, and radiation-induced imaging changes. Ninety evaluable patients had undergone GKS, with a mean endocrine follow-up duration of 45 months (range 12–132 months). The mean dose to the tumor margin was 23 Gy (median 25 Gy).

Normal 24-hour UFC levels were achieved in 49 patients (54%), with an average time of 13 months after treatment (range 2–67 months). In the 49 patients in whom a tumor was visible on the planning magnetic resonance (MR) image, a decrease in tumor size occurred in 39 (80%), in seven patients there was no change in size, and tumor growth occurred in three patients. Ten patients (20%) experienced a relapse of Cushing's disease after initial remission; the mean time to recurrence was 27 months (range 6–60 months). Seven of these patients underwent repeated GKS, with three patients achieving a second remission. New hormone deficiencies developed in 20 patients (22%), with hypothyroidism being the most common endocrinopathy after GKS. Five patients experienced new visual deficits or third, fourth, or sixth cranial nerve deficits; two of these patients had undergone prior conventional fractionated radiation therapy, and four of them had received previous GKS. Radiation-induced changes were observed on MR images in three patients; one had symptoms attributable to these changes.

Conclusions

Gamma Knife surgery is an effective treatment for persistent Cushing's disease. Adenomas with cavernous sinus invasion that are not amenable to resection are treatable with the Gamma Knife. A second GKS treatment appears to increase the risk of cranial nerve damage. These results demonstrate the value of combining two neurosurgical treatment modalities—microsurgical resection and GKS—in the management of pituitary adenomas.

Pitfalls in the management of Cushing’s disease

Cushing's disease is caused by functional corticotroph adenomas of the pituitary gland, most commonly noninvasive microadenomas. Transsphenoidal microsurgery is an effective means of control for patients with adrenocorticotrophic hormone-producing microadenomas. However, a wide variation of clinical outcomes and recurrence rates has been reported. The major causes of surgical failure in the treatment of Cushing's disease lies in inadequate preoperative evaluation, unsuccessful identification of the adenoma and inexperience of the surgeon. Furthermore, appropriate use of combination therapy, including surgery, radiotherapy, radiosurgery and adrenalectomy can improve the outcome. For optimal results in this rare disease, endocrinological, radiological and surgical procedures should be co-ordinated in a specialized center. In this review, factors affecting preoperative evaluation, surgical success and outcome are outlined in the light of current knowledge.

Long-term follow-up results of postoperative radiation therapy for Cushing’s disease

OBJECTIVES

Radiotherapy is currently used in patients with residual or recurrent pituitary adenomas after surgery. However, there is little information of long-term outcome of patients with Cushing's disease following radiotherapy. We assessed the long-term efficacy and toxicity of conventional radiotherapy in the control of Cushing's disease after unsuccessful transsphenoidal surgery.

PATIENTS AND METHODS

Forty patients with Cushing's disease were treated with conventional external beam radiotherapy at our Institution between 1988 and 2002. The median age was 38. All patients received radiotherapy following unsuccessful surgery or at tumour recurrence to a dose of 45-50 Gy in 25-28 fractions. The persistence of active disease after surgery was diagnosed by the increased high plasma cortisol levels, high 24 h urinary cortisol levels and absence of cortisol suppression after administration of dexamethasone.

RESULTS

The 5 and 10 year local tumour control was 93% and the 5 and 10 year survival was 97 and 95%. Normalization of plasma cortisol was seen in 28% of patients at 1 year, 73% at 3 years, 78% at 5 years and 84% at 10 years. The average timing to remission was 24 months. The most common side effect was hypopituitarism that increased progressively during the follow-up, being present in 62% and in 76% of patients at 5 and 10 years after RT. There were no other serious complications as radiation induced optic neuropathy or second tumours.

CONCLUSION

Radiotherapy is effective in the long-term tumour- and hormone hypersecretion control of ACTH-secreting pituitary adenomas, however with a high prevalence of hypopituitarism. At the moment, it remains an important treatment option after failure of surgery.

Gamma knife radiosurgery is a successful adjunctive treatment in Cushing's disease

OBJECTIVE

Though transsphenoidal surgery remains the first-line treatment of Cushing's disease, recurrence occurs frequently. Conventional radiotherapy and anticortisolic drugs both have adverse effects. Stereotactic radiosurgery needs to be evaluated more precisely. The aim of this study was to determine long-term hormonal effects and tolerance of gamma knife (GK) radiosurgery in Cushing's disease.

DESIGN

Forty patients with Cushing's disease treated by GK were prospectively studied over a decade, with a mean follow-up of 54.7 months. Eleven of them were treated with GK as a primary treatment.

METHODS

Radiosurgery was performed at the Department of Functional Neurosurgery of Marseille, France, using the Leksell Gamma Unit B and C models. Median margin dose was 29.5 Gy. Patients were considered in remission if they had normalized 24-h free urinary cortisol and suppression of plasma cortisol after low-dose dexamethasone suppression test.

RESULTS

Seventeen patients (42.5%) were in remission after a mean of 22 months (range 12-48 months). The two groups did not differ in terms of initial hormonal levels. Target volume was significantly higher in uncured than in remission group (909.8 vs 443 mm(3), P = 0.038). We found a significant difference between patients who were on or off anticortisolic drugs at the time of GK (20 vs 48% patients in remission respectively, P = 0.02).

CONCLUSION

With 42% of patients in remission after a median follow-up of 54 months, GK stereotactic radiosurgery, especially as an adjunctive treatment to surgery, may represent an alternative to other therapeutic options in view of their adverse effects.

Visual field preservation after multisession cyberknife radiosurgery for perioptic lesions

OBJECTIVE

The restricted radiation tolerance of the anterior visual pathways represents a unique challenge for ablating adjacent lesions with single-session radiosurgery. Although preliminary studies have recently demonstrated that multisession radiosurgery for selected perioptic tumors is both safe and effective, the number of patients in these clinical series was modest and the length of follow-up limited. The current retrospective study is intended to help address these shortcomings.

METHODS

Forty-nine consecutive patients with meningioma (n = 27), pituitary adenoma (n = 19), craniopharyngioma (n = 2), or mixed germ cell tumor (n = 1) situated within 2 mm of a "short segment" of the optic apparatus underwent multisession image-guided radiosurgery at Stanford University Medical Center. Thirty-nine of these patients had previous subtotal surgical resection, and six had previously been treated with conventional fractionated radiotherapy (6). CyberKnife radiosurgery was delivered in two to five sessions to an average tumor volume of 7.7 cm3 and a cumulative average marginal dose of 20.3 Gy. Formal visual testing and clinical examinations were performed before treatment and at follow-up intervals beginning at 6 months.

RESULTS

After a mean visual field follow-up of 49 months (range, 6-96 mo), vision was unchanged postradiosurgery in 38 patients, improved in eight (16%), and worse in three (6%). In each instance, visual deterioration was accompanied by tumor progression that ultimately resulted in patient death. However, one of these patients, who had a multiply recurrent adrenocorticotropic hormone-secreting pituitary adenoma, initially experienced early visual loss without significant tumor progression after both a previous course of radiotherapy and three separate sessions of radiosurgery. After a mean magnetic resonance imaging follow-up period of 46 months, tumor volume was stable or smaller in all other cases. Two patients died of unrelated nonbrain causes.

CONCLUSION

Multisession radiosurgery resulted in high rates of tumor control and preservation of visual function in this group of perioptic tumors. Ninety-four percent of patients retained or improved preradiosurgical vision. This intermediate-term experience reinforces the findings from earlier studies that suggested that multisession radiosurgery can be a safe and effective alternative to either surgery or fractionated radiotherapy for selected lesions immediately adjacent to short segments of the optic apparatus.

Hypertension in Cushing's syndrome

Cushing's syndrome can be exogenous, resulting from the administration of glucocorticoids or adrenocorticotrophic hormone (ACTH), or endogenous, secondary to increased secretion of cortisol or ACTH. Hypertension is one of the most distinguishing features of endogenous Cushing's syndrome, as it is present in about 80% of adult patients and in almost half of children and adolescents patients. Hypertension results from the interplay of several pathophysiological mechanisms regulating plasma volume, peripheral vascular resistance and cardiac output, all of which may be increased. The therapeutic goal is to find and remove the cause of excess glucocorticoids, which, in most cases of endogenous Cushing's syndrome, is achieved surgically. Treatment of Cushing's syndrome usually results in resolution or amelioration of hypertension. However, some patients may not achieve normotension or may require a prolonged period of time for the correction of hypercortisolism. Therefore, therapeutic strategies for Cushing's-specific hypertension (to normalise blood pressure and decrease the duration of hypertension) are necessary to decrease the morbidity and mortality associated with this disorder. The various pathogenetic mechanisms that have been proposed for the development of glucocorticoid-induced hypertension in Cushing's syndrome and its management are discussed.

Surgical Treatment of Recurrent Cushing's Disease

OBJECTIVE:

The aim of this study was to evaluate the role of transsphenoidal selective adenomectomy alone or in combination with adjuvant therapy in treatment of recurrent Cushing's disease.

METHODS:

A total of 16 patients with recurrent Cushing's disease underwent reoperation, 15 via a transsphenoidal approach and one via a combined transsphenoidal/transcranial approach. Selective adenomectomies were performed in 13 patients and hemihypophysectomies were performed in three patients. Endocrinologically, recurrence was diagnosed by an overnight 2-mg dexamethasone suppression test. All patients underwent a 1.5-T magnetic resonance imaging scan, and eight patients underwent inferior petrosal sinus sampling.

RESULTS:

After selective adenomectomy, six of the 13 patients went into remission. Recurrence always occurred at the localization of the original tumor. In three patients without intraoperative tumor detection, hypophysectomy did not lead to remission. In 10 patients with persistent disease, adjuvant therapy (radiotherapy, adrenalectomy) led to normalization of basal cortisol levels in eight patients and clinical remission in one patient. One patient was lost to follow-up. In 10 patients, no evidence of an adenoma was visible on the preoperative magnetic resonance imaging scan. Inferior petrosal sinus sampling allowed correct prediction of the tumor localization in two of eight patients.

CONCLUSION:

By performing repeated selective adenomectomy, patients with recurrent Cushing's disease can be cured without the risk of endocrine deficits or major complications. Dynamic endocrine tests are of paramount importance for surgical decision making. Imaging and inferior petrosal sinus sampling are not helpful in locating the recurrent tumor. If normalization can not be achieved, adjuvant therapy is mandatory.

Repeated transsphenoidal surgery to treat recurrent or residual pituitary adenoma

Object. In this paper the authors describe the indications for and the results and complications of repeated transsphenoidal surgery (RTSS) to treat recurrent or residual pituitary adenoma.

Methods. A retrospective review was conducted of 96 consecutive patients who underwent RTSS to treat recurrent or residual pituitary adenoma. Ninety-six patients underwent RTSS: 42 to treat a recurrent or residual pituitary mass and 54 to treat a recurrent or persistent hormone hypersecretion. There was no case of perioperative death and there was a 1% incidence of major complications. Postoperative endocrinological deficiencies were uncommon unless planned total hypophysectomy was performed to treat Cushing disease. Clinical remission occurred in 93% of patients undergoing RTSS to treat a tumor mass, and 15% of patients initially experienced remission only to face a relapse after a mean of 32 months. Endocrinological remission occurred in 57% of patients undergoing RTSS to treat hormone hypersecretion; most of these patients had Cushing disease. Thirty-five percent of patients with an initial endocrinological remission experienced a relapse of their symptoms after a mean of 31 months (thus, 37% of patients achieved sustained endocrinological remission). We failed to identify factors that accurately predicted initial symptom remission or delayed relapse following RTSS. Ten patients in our series eventually underwent a third transsphenoidal surgery without major complications.

Conclusions. Repeated transsphenoidal surgery is a more effective treatment for recurrent or residual mass than it is for hormone hypersecretion and has acceptable rates of morbidity and mortality. If hypophysectomy is not performed, endocrinological deficiencies are unlikely following RTSS.

Treatment of pituitary adenomas by fractionated stereotactic radiotherapy: A prospective study of 110 patients

PURPOSE

To optimize and reduce the toxicity of pituitary adenoma irradiation by assessing the feasibility and effectiveness of fractionated stereotactic radiotherapy (FSR).

METHODS AND MATERIALS

Between 1990 and 1999, 110 consecutive patients, 47 with a functioning adenoma, were treated according to a strategy of either early surgery and FSR (n = 89) or FSR only (n = 21). Of the 110 patients, 75 had persistent macroscopic tumor and 47 persistent hormonal secretions; 15 were treated in the prophylactic setting. The linear accelerator-delivered dose was 50.4 Gy (5 x 1.8 Gy weekly), with a 2-mm safety margin.

RESULTS

After a minimal follow-up of 48 months, only 1 patient had developed progression. Of the 110 patients, 27 (36%) had a complete tumor response, 67 (89.3%) had an objective tumor response, 20 (42%) had a hormonal complete response, and 47 (100%) had a hormonal objective tumor response. The proportion of patients without a complete tumor response, objective tumor response, complete hormonal response, and objective hormonal response was 85.1%, 62%, 83%, and 59.3% at 4 years and 49.3%, 9%, 59.3%, and 10.6% at 8 years, respectively. The sole unfavorable predictive factor was preoperative SSE >20 mm for tumor response (p = 0.01) and growth hormone adenoma for the hormonal response (p <0.001). No late complications, except for pituitary deficiency, were reported, with a probability of requiring hormonal replacement of 28.5% and 35% at 4 and 8 years, respectively. Nonfunctioning status was the sole unfavorable factor (p = 0.0016).

CONCLUSIONS

Surgery plus FSR is safe and effective. FSR focused to the target volume seems more suitable than standard radiotherapy, and standard fractionation reduces the risk of optic neuropathy sometimes observed after single-dose radiosurgery. Therefore, FSR allows us to consider combined transrhinoseptal surgery and early radiotherapy, with a curative goal without patient selection.

Stereotactic radiosurgery for pituitary adenomas: an intermediate review of its safety, efficacy, and role in the neurosurgical treatment armamentarium

OBJECT

Pituitary adenomas are very common neoplasms, constituting between 10 and 20% of all primary brain tumors. Historically, the treatment armamentarium for pituitary adenomas has included medical management, microsurgery, and fractionated radiotherapy. More recently, radiosurgery has emerged as a viable treatment option. The goal of this research was to define more fully the efficacy, safety, and role of radiosurgery in the treatment of pituitary adenomas.

METHODS

Medical literature databases were searched for articles pertaining to pituitary adenomas and stereotactic radiosurgery. Each study was examined to determine the number of patients, radiosurgical parameters (for example, maximal dose and tumor margin dose), duration of follow-up review, tumor growth control rate, complications, and rate of hormone normalization in the case of functioning adenomas. A total of 35 peer-reviewed studies involving 1621 patients were examined. Radiosurgery resulted in the control of tumor size in approximately 90% of treated patients. The reported rates of hormone normalization for functioning adenomas varied substantially. This was due in part to widespread differences in endocrinological criteria used for the postradiosurgical assessment. The risks of hypopituitarism, radiation-induced neoplasia, and cerebral vasculopathy associated with radiosurgery appeared lower than those for fractionated radiation therapy. Nevertheless, further observation will be required to understand the true probabilities. The incidence of other serious complications following radiosurgery was quite low.

CONCLUSIONS

Although microsurgery remains the primary treatment modality in most cases, stereotactic radiosurgery offers both safe and effective treatment for recurrent or residual pituitary adenomas. In rare instances, radiosurgery may be the best initial treatment for patients with pituitary adenomas. Further refinements in the radiosurgical technique will likely lead to improved outcomes.

Long-term results of gamma knife surgery for growth hormone-producing pituitary adenoma: is the disease difficult to cure?

OBJECT

The authors conducted a study to determine the long-term results of gamma knife surgery for residual or recurrent growth hormine (GH)-producing pituitary adenomas and to compare the results with those after treatment of other pituitary adenomas.

METHODS

The series consisted of 67 patients. The mean tumor diameter was 19.2 mm and volume was 5.4 cm3. The mean maximum dose was 35.3 Gy and the mean margin dose was 18.9 Gy. The mean follow-up duration was 63.3 months (range 13-142 months). The tumor resolution rate was 2%, the response rate 68.3%, and the control rate 100%. Growth hormone normalization (GH < 1.0 ng/ml) was found in 4.8%, nearly normal (< 2.0 ng/ml) in 11.9%, significantly decreased (< 5.0 ng/ml) in 23.8%, decreased in 21.4%, unchanged in 21.4%, and increased in 16.7%. Serum insulin-like growth factor (IGF)-1 was significantly decreased (IGF-1 < 400 ng/ml) in 40.7%, decreased in 29.6%, unchanged in 18.5%, and increased in 11.1%, which was almost parallel to the GH changes.

CONCLUSIONS

Gamma knife surgery was effective and safe for the control of tumors; however, normalization of GH and IGF-1 secretion was difficult to achieve in cases with large tumors and low-dose radiation. Gamma knife radiosurgery is thus indicated for small tumors after surgery or medication therapy when a relatively high-dose radiation is required.

The efficacy of linear accelerator radiosurgery in the management of patients with Cushing's disease

We identified 35 patients who had undergone stereotactic radiosurgery (SRS) for their biochemically proven Cushing's disease in order to assess the efficacy of SRS with regard to control of hypercortisolism, improvement of clinical features and prevention of tumor progression, and subsequent incidence of hypopituitarism. Seventeen (49%) patients achieved control of their cortisol levels following SRS; the mean time to normalization was 7.5 months (range: 1-33). Four (19%) patients experienced recurrent hypercortisolism at a mean time of 35.5 months following therapy (range: 17-64). Control of tumor progression was achieved in 91% patients. Fourteen (40%) patients demonstrated a new pituitary deficiency following SRS. Our results suggest that cortisol levels are normalized more efficiently and with a lower recurrence rate with SRS than with conventional fractionated external beam radiotherapy (EBT). We have confirmed the near 100% tumor control rate reported with SRS. The percentage of patients developing pituitary insufficiency following SRS is less than that of patients having undergone EBT; however, deficits occurred up to 10 years posttreatment. We advocate the use of SRS as the primary therapeutic modality in those patients who are poor surgical candidates, or as the adjunct treatment to microsurgery in eliminating residual tumor cells or disease that is not easily amenable to resection.