Megavoltage pituitary irradiation in the management of Cushing's disease and Nelson's syndrome: long-term follow-up

Management of Nelson’s Syndrome

Nelson’s syndrome is a potentially severe condition that may develop in patients with Cushing’s disease treated with bilateral adrenalectomy. Its management can be challenging. Pituitary surgery followed or not by radiotherapy offers the most optimal tumour control, whilst pituitary irradiation alone needs to be considered in cases requiring intervention and are poor surgical candidates. Observation is an option for patients with small lesions, not causing mass effects to vital adjacent structures but close follow-up is required for a timely detection of corticotroph tumour progression and for further treatment if required. To date, no medical therapy has been consistently proven to be effective in Nelson’s syndrome. Pharmacotherapy, however, should be considered when other management approaches have failed. A subset of patients with Nelson’s syndrome may develop further tumour growth after primary treatment, and, in some cases, a truly aggressive tumour behaviour can be demonstrated. In the absence of evidence-based guidance, the management of these cases is individualized and tailored to previously offered treatments. Temozolomide has been used in patients with aggressive Nelson’s with no consistent results. Development of tumour-targeted therapeutic agents are an unmet need for the management of aggressive cases of Nelson’s syndrome.

Updates in the outcomes of radiation therapy for Cushing's disease

External radiation therapy (RT) directed to the pituitary gland is generally recommended in patients with Cushing's disease (CD) as adjuvant to transsphenoidal surgery, among other second-line therapies offered to patients with residual or recurrent hypercortisolism (i.e., medical treatment, repeat surgery or bilateral adrenalectomy). RT is effective for the control of tumor growth, even in invasive tumors and in Nelson's syndrome. Progress in radiation stereotactic techniques lead to improved tumor targeting and radiation delivery, thus sparing the adjacent brain structures. Stereotactic RT is associated with a 55-65% rate of cortisol normalization after several months to a few years and potentially with a lower risk of long-term complications, compared with conventional RT. Cortisol-lowering medical therapy is recommended while awaiting the radiation effects. Hypopituitarism is the most frequent side-effect, damage to optic or cranial nerves or second brain tumors are rarely reported. This review presents the updates in the efficacy and safety of the stereotactic radiation techniques in CD patients. Practical points which should be considered by the clinician before recommending RT are also presented.

Corticotroph tumor progression after bilateral adrenalectomy (Nelson's syndrome): systematic review and expert consensus recommendations

BACKGROUND

Corticotroph tumor progression (CTP) leading to Nelson's syndrome (NS) is a severe and difficult-to-treat complication subsequent to bilateral adrenalectomy (BADX) for Cushing's disease. Its characteristics are not well described, and consensus recommendations for diagnosis and treatment are missing.

METHODS

A systematic literature search was performed focusing on clinical studies and case series (≥5 patients). Definition, cumulative incidence, treatment and long-term outcomes of CTP/NS after BADX were analyzed using descriptive statistics. The results were presented and discussed at an interdisciplinary consensus workshop attended by international pituitary experts in Munich on October 28, 2018.

RESULTS

Data covered definition and cumulative incidence (34 studies, 1275 patients), surgical outcome (12 studies, 187 patients), outcome of radiation therapy (21 studies, 273 patients), and medical therapy (15 studies, 72 patients).

CONCLUSIONS

We endorse the definition of CTP-BADX/NS as radiological progression or new detection of a pituitary tumor on thin-section MRI. We recommend surveillance by MRI after 3 months and every 12 months for the first 3 years after BADX. Subsequently, we suggest clinical evaluation every 12 months and MRI at increasing intervals every 2-4 years (depending on ACTH and clinical parameters). We recommend pituitary surgery as first-line therapy in patients with CTP-BADX/NS. Surgery should be performed before extrasellar expansion of the tumor to obtain complete and long-term remission. Conventional radiotherapy or stereotactic radiosurgery should be utilized as second-line treatment for remnant tumor tissue showing extrasellar extension.

Outcomes of Patients with Nelson's Syndrome after Primary Treatment: A Multicenter Study from 13 UK Pituitary Centers

CONTEXT

Long-term outcomes of patients with Nelson's syndrome (NS) have been poorly explored, especially in the modern era.

OBJECTIVE

To elucidate tumor control rates, effectiveness of various treatments, and markers of prognostic relevance in patients with NS.

PATIENTS, DESIGN, AND SETTING

Retrospective cohort study of 68 patients from 13 UK pituitary centers with median imaging follow-up of 13 years (range 1-45) since NS diagnosis.

RESULTS

Management of Cushing's disease (CD) prior to NS diagnosis included surgery+adrenalectomy (n = 30; eight patients had 2 and one had 3 pituitary operations), surgery+radiotherapy+adrenalectomy (n = 17; two received >1 courses of irradiation, two had ≥2 pituitary surgeries), radiotherapy+adrenalectomy (n = 2), and adrenalectomy (n = 19). Primary management of NS mainly included surgery, radiotherapy, surgery+radiotherapy, and observation; 10-year tumor progression-free survival was 62% (surgery 80%, radiotherapy 52%, surgery+radiotherapy 81%, observation 51%). Sex, age at CD or NS diagnosis, size of adenoma (micro-/macroadenoma) at CD diagnosis, presence of pituitary tumor on imaging prior adrenalectomy, and mode of NS primary management were not predictors of tumor progression. Mode of management of CD before NS diagnosis was a significant factor predicting progression, with the group treated by surgery+radiotherapy+adrenalectomy for their CD showing the highest risk (hazard ratio 4.6; 95% confidence interval, 1.6-13.5). During follow-up, 3% of patients had malignant transformation with spinal metastases and 4% died of aggressively enlarging tumor.

CONCLUSIONS

At 10 years follow-up, 38% of the patients diagnosed with NS showed progression of their corticotroph tumor. Complexity of treatments for the CD prior to NS diagnosis, possibly reflecting corticotroph adenoma aggressiveness, predicts long-term tumor prognosis.

Outcomes of stereotactic radiosurgery and hypofractionated stereotactic radiotherapy for refractory Cushing's disease

PURPOSE

Hypofractionated stereotactic radiotherapy (HSRT) for refractory Cushing's disease may offer a condensed treatment schedule for patients with large tumors abutting the optic chiasm unsuitable for stereotactic radiosurgery (SRS). To-date only four patients have been treated by HSRT in the published literature. We investigated the feasibility, toxicity, and efficacy of HSRT compared to SRS.

METHODS

After approval, we retrospectively evaluated patients treated at our institution for refractory Cushing's disease with SRS or HSRT. Study outcomes included biochemical control, time to biochemical control, local control, and late complications. Binary logistic regression and Cox proportional hazards regression evaluated predictors of outcomes.

RESULTS

Patients treated with SRS (n = 9) and HSRT (n = 9) were enrolled with median follow-up of 3.4 years. Clinicopathologic details were balanced between the cohorts. Local control was 100% in both cohorts. Time to biochemical control was 6.6. and 9.5 months in the SRS and HSRT cohorts, respectively (p = 0.6258). Two patients in each cohort required salvage bilateral adrenalectomy. Late complications including secondary malignancy, radionecrosis, cranial nerve neuropathy, and optic pathway injury were minimal for either cohort.

CONCLUSIONS

HSRT is an appropriate treatment approach for refractory Cushing's disease, particularly for patients with large tumors abutting the optic apparatus. Prospective studies are needed to validate these findings and identify factors suggesting optimal fractionation approaches.

Gamma Knife radiosurgery for the treatment of Nelson's syndrome: a multicenter, international study

OBJECTIVE

Nelson's syndrome is a rare and challenging neuroendocrine disorder, and it is associated with elevated adrenocorticotrophic hormone (ACTH) level, skin hyperpigmentation, and pituitary adenoma growth. Management options including resection and medical therapy are traditional approaches. Ionizing radiation in the form of Gamma Knife radiosurgery (GKRS) is also being utilized to treat Nelson's syndrome. In the current study the authors sought to better define the therapeutic role of stereotactic radiosurgery (SRS) in Nelson's syndrome.

METHODS

Study patients with Nelson's syndrome were treated with single-fraction GKRS (median margin dose of 25 Gy) at 6 different centers as part of an International Radiosurgery Research Foundation (IRRF) investigation. Data including neurological function, endocrine response, and radiological tumor response were collected and sent to the study-coordinating center for review. Fifty-one patients with median endocrine and radiological follow-ups of 91 and 80.5 months from GKRS, respectively, were analyzed for endocrine remission, tumor control, and neurological outcome. Statistical methods were used to identify prognostic factors for these endpoints.

RESULTS

At last follow-up, radiological tumor control was achieved in 92.15% of patients. Endocrine remission off medical management and reduction in pre-SRS ACTH level were achieved in 29.4% and 62.7% of patients, respectively. Improved remission rates were associated with a shorter time interval between resection and GKRS (p = 0.039). Hypopituitarism was seen in 21.6% and new visual deficits were demonstrated in 15.7% of patients.

CONCLUSIONS

GKRS affords a high rate of pituitary adenoma control and improvement in ACTH level for the majority of Nelson's syndrome patients. Hypopituitarism is the most common adverse effect from GKRS in Nelson's syndrome patients and warrants longitudinal follow-up for detection and endocrine replacement.

Radiotherapy as a tool for the treatment of Cushing's disease

Treatment of Cushing's disease (CD) is one of the most challenging tasks in endocrinology. The first-line treatment, transsphenoidal pituitary surgery, is associated with a high failure rate and a high prevalence of recurrence. Re-operation is associated with an even higher rate of a failure and recurrence. There are three main second-line treatments for CD - pituitary radiation therapy (RT), bilateral adrenalectomy and chronic cortisol-lowering medical treatment. All these treatments have their limitations. While bilateral adrenalectomy provides permanent cure of the hypercortisolism in all patients, the unavoidable chronic adrenal insufficiency and the risk of development of Nelson syndrome are of concern. Chronic cortisol-lowering medical treatment is not efficient in all patients and side effects are often a limiting factor. RT is efficient for approximately two-thirds of all patients with CD. However, the high prevalence of pituitary insufficiency is of concern as well as potential optic nerve damage, development of cerebrovascular disease and secondary brain tumours. Thus, when it comes to decide appropriate treatment for patients with CD, who have either failed to achieve remission with pituitary surgery, or patients with recurrence, the pros and cons of all second-line treatment options must be considered.

Outcomes of Pituitary Radiation for Cushing's Disease

Achievement of biochemical remission with preservation of normal pituitary function is the goal of treatment for Cushing's disease. For patients with persistent or recurrent Cushing's disease after transsphenoidal resection, radiation therapy may be a safe and effective treatment. Stereotactic radiosurgery is favored over conventional fractionated external beam radiation. Hormonal recurrence rates range from 0% to 36% at 8 years after treatment. Tumor control rates are high. New pituitary hormone deficiency is the most common adverse effect after stereotactic radiosurgery and external beam radiation. The effects of radiation planning optimization and use of adjuvant medication on endocrine remission rates warrant investigation.

STEREOTACTIC RADIATION THERAPY IN PITUITARY ADENOMAS, IS IT BETTER THAN CONVENTIONAL RADIATION THERAPY?

Pituitary radiotherapy (RT) has undergone important progress in the last decades due to the development of new stereotactic techniques which provide more precise tumour targeting with less overall radiation received by the adjacent brain structures. Pituitary surgery is usually first-line therapy in most patients with nonfunctioning (NFPA) and functioning adenomas (except for prolactinomas and large growth hormone (GH) secreting adenomas), while RT is used as second or third-line therapy. The benefits of RT (tumour volume control and, in functional tumours, decreased hormonal secretion) are hampered by the long latency of the effect and the potential side effects. This review presents the updates in the efficacy and safety of the new stereotactic radiation techniques in patients with NFPA, GH-, ACTH- or PRL-secreting pituitary adenomas.

Methods

A systematic review was performed using PubMed and articles/abstracts and reviews detailing RT in pituitary adenomas from 2000 to 2017 were included.

Results

Stereotactic radiosurgery (SRS) and fractionated stereotactic RT (FSRT) provide high rates of tumour control i.e. stable or decrease in tumour size, in all types of pituitary adenomas (median 92 - 98%) at 5 years. Endocrinological remission is however significantly lower: 44-52% in acromegaly, 54-64% in Cushing's disease and around 30% in prolactinomas at 5 years. The rate of new hypopituitarism varies from 10% to 50% at 5 years in all tumour types and as expected increases with the duration of follow-up (FU). The risk for other radiation-induced complications is usually low (0-5% for new visual deficits, cranial nerves damage or brain radionecrosis and extremely low for secondary brain tumours), however longer FU is needed to determine rates of secondary tumours. Notably, in acromegaly, there may be a higher risk for stroke with FSRT.

Conclusion

Stereotactic radiotherapy can be an effective treatment option for patients with persistent or recurrent pituitary adenomas after unsuccessful surgery (especially if residual tumour is enlarging) and/or resistance or unavailability of medical therapy. Comparison with conventional radiation therapy (CRT) is rather difficult, due to the substantial heterogeneity of the studies. In order to evaluate the potential brain-sparing effect of the new stereotactic techniques, suggested by the current data, long-term studies evaluating secondary morbidity and mortality are 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.

Long-term remission and recurrence rates in Cushing's disease: predictive factors in a single-centre study

OBJECTIVE

To investigate the early and late outcomes of patients with Cushing's disease (CD) submitted to a neurosurgical procedure as first-line treatment.

DESIGN

In this single-centre retrospective case notes study, 131 patients with CD with a minimum follow-up period of 6 years (124 operated by transsphenoidal surgery (TSS) and seven by the transcranial approach) were studied. Apparent immediate cure: post-operative 0900 h serum cortisol level <50 nmol/l; remission: cortisol insufficiency or restoration of 'normal' cortisol levels with resolution of clinical features; and recurrence: dexamethasone resistance and relapse of hypercortisolaemic features.

RESULTS

In patients operated by TSS, remission of hypercortisolaemia was found in 72.8% of 103 microadenomas and 42.9% of 21 macroadenomas, with recurrence rates 22.7 and 33.3% respectively with a 15-year mean follow-up (range, 6-29 years). Of 27 patients with microadenomas operated after 1991, with positive imaging and pathology, 93% obtained remission with 12% recurrence. In multivariate analysis, the time needed to achieve recovery of hypothalamo-pituitaryadrenal axis was the only significant predictor of recurrence; all patients who recurred showed recovery within 3 years from surgery: 31.3% of patients had total hypophysectomy with no recurrence; 42% of patients with selective adenomectomy and 26.5% with hemi-hypophysectomy showed recurrence rates of 31 and 13% respectively (χ(2)=6.275, P=0.03). Strict remission criteria were not superior in terms of the probability of recurrence compared with post-operative normocortisolaemia.

CONCLUSIONS

Lifelong follow-up for patients with CD appears essential, particularly for patients who have shown rapid recovery of their axis. The strict criteria previously used for 'apparent cure' do not appear to necessarily predict a lower recurrence rate.

Radiotherapy in paediatric Cushing's disease: efficacy and long term follow up of pituitary function

Pituitary radiotherapy (RT) is an effective second-line treatment for paediatric Cushing's disease (CD). We report long-term efficacy and anterior pituitary function in a cohort of paediatric CD patients treated with RT. Between 1988 and 2008, from our cohort of 48 paediatric CD patients, eight paediatric CD patients (5 males and 3 females) underwent second-line pituitary RT (45 Gy in 25 fractions), following unsuccessful transsphenoidal surgery. Out of eight whose long term follow up is available, four patients were cured by RT. Minimum follow up of 2 years is available for all patients. Four patients achieved cure after RT. Two patients were not cured even after follow up of 60 and 132 months, respectively. Out of four uncured patients, two of them had suppressible low dose dexamethasone cortisol with altered circadian rhythm suggesting possibility of response in near future with follow up of just 26 months. Five patients were hypogonadal and one patient was hypothyroid. All patients were below their target height at the time of last follow up. None of the patients had posterior pituitary dysfunction. This series of patients illustrates the efficacy and long-term follow up of pituitary function in children with CD treated with RT. This study also emphasizes the need of growth hormone statues assessment and timely intervention.

Nelson's syndrome

Nelson's syndrome is a potentially life-threatening condition that does not infrequently develop following total bilateral adrenalectomy (TBA) for the treatment of Cushing's disease. In this review article, we discuss some controversial aspects of Nelson's syndrome including diagnosis, predictive factors, aetiology, pathology and management based on data from the existing literature and the experience of our own tertiary centre. Definitive diagnostic criteria for Nelson's syndrome are lacking. We argue in favour of a new set of criteria. We propose that Nelson's syndrome should be diagnosed in any patient with prior TBA for the treatment of Cushing's disease and with at least one of the following criteria: i) an expanding pituitary mass lesion compared with pre-TBA images; ii) an elevated 0800 h plasma level of ACTH (>500 ng/l) in addition to progressive elevations of ACTH (a rise of >30%) on at least three consecutive occasions. Regarding predictive factors for the development of Nelson's syndrome post TBA, current evidence favours the presence of residual pituitary tumour on magnetic resonance imaging (MRI) post transsphenoidal surgery (TSS); an aggressive subtype of corticotrophinoma (based on MRI growth rapidity and histology of TSS samples); lack of prophylactic neoadjuvant pituitary radiotherapy at the time of TBA and a rapid rise of ACTH levels in year 1 post TBA. Finally, more studies are needed to assess the efficacy of therapeutic strategies in Nelson's syndrome, including the alkylating agent, temozolomide, which holds promise as a novel and effective therapeutic agent in the treatment of associated aggressive corticotroph tumours. It is timely to review these controversies and to suggest guidelines for future audit.

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.

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.

Gamma Knife surgery for invasive pituitary macroadenoma

OBJECT

Pituitary adenomas have been treated using a variety of modalities including resection, medication, fractionated radiotherapy, and stereotactic radiosurgery. The policy has been that all adenomas should first be treated with resection to reduce the volume of the tumor. The authors' study was conducted to determine the efficacy of using Gamma Knife surgery (GKS) for pituitary adenomas invading the cavernous sinus.

METHODS

Of 397 patients with pituitary tumors who underwent GKS between October 1994 and October 2005, 68 patients had pituitary macroadenomas invading the cavernous sinus. Sixty-seven cases were available for follow up. The mean age of the patients in these cases was 42.8 years (range 14-73 years). The male/female ratio was 0.8:1. The mean adenoma volume was 9.3 cm3. A total of 24 patients had undergone craniotomies and resection, and 11 patients had undergone transsphenoidal surgery prior to GKS. The mean follow-up period was 32.8 months. Tumor control was defined as a decrease or no change in tumor volume after GKS. Endocrinological improvement was defined as a decline in hormone levels to below 50% of the pre-GKS level. Tumor control was achieved in 95.5% of the cases. Endocrinological improvement was achieved in 68% of 25 patients. One patient suffered hypopituitarism after GKS.

CONCLUSIONS

Gamma Knife surgery is a safe and effective treatment for invasive pituitary macroadenoma with few complications.

Treatment of Nelson's syndrome with temozolomide

A 64-year-old woman was previously treated for Cushing's disease with trans-sphenoidal surgery, external beam radiotherapy and bilateral adrenalectomy. Progression of an aggressive corticotroph adenoma was evident 3 years post-adrenalectomy; involvement of the clivus was treated with surgery and gamma knife radiosurgery. Tumour spread through the skull base, occiput and left ear with persistent facial pain and left ear discharge; progression continued despite second gamma knife treatment. ACTH levels peaked at 2472 and 2265 pmol/l pre- and post-hydrocortisone respectively. Treatment with temozolomide resulted in a significant improvement in symptoms, a reduction of plasma ACTH to 389 pmol/l and regression of tumour on magnetic resonance imaging scan after four cycles of treatment. We propose that temozolomide is an effective and well-tolerated therapeutic tool for the treatment of Nelson's syndrome and a useful addition to the range of therapies available to treat this condition.

Nelson's Syndrome

Nelson's syndrome is a potentially severe complication of bilateral adrenalectomy performed in the treatment of Cushing's disease, and its management remains difficult. Of all of the features of Nelson's syndrome, the one that causes most concern is the development of a locally aggressive pituitary tumour, which, unusually for pituitary disease, may occasionally cause death from the tumour itself. This feature is especially pertinent given the increasing use in Cushing's disease of laparoscopic bilateral adrenal surgery as a highly effective treatment modality to control cortisol-excess. Despite numerous studies and reports, there is no formal consensus of what defines Nelson's syndrome. Thus, some will define Nelson's syndrome according to the classical description with an evolving pituitary mass after bilateral adrenalectomy, whereas others will rely on increasing plasma ACTH levels, even in the absence of a clear pituitary mass lesion on MRI. These factors need to be borne in mind when considering the reports of Nelson's syndrome, as there is great heterogeneity, and it is likely that overall the modern 'Nelson's syndrome' represents a different disease entity from that of the last century. In the present paper, clinical and epidemiological features of Nelson's syndrome, as well as its treatment modalities, are reviewed.

Applications of radiotherapy and radiosurgery in the management of pediatric Cushing's disease: a review of the literature and our experience

Surgical extirpation of pituitary adenomas is considered the mainstay of therapy in pediatric patients with Cushing's disease. However, a small subset of patients will require adjuvant therapy either due to tumor invasiveness, or disease recurrence. Conventional radiation therapy (or radiotherapy) delivers ionizing radiation to control hormonally active cells in fractionated doses (spread out over time) in order to give normal cells time to recover, while radiosurgery involves focusing a high dose of radiation structures in a single treatment session to the adenoma while generally sparing the normal gland and surrounding of any substantial amount of radiation. This paper reviews the effectiveness of radiation in the treatment of pediatric Cushing's disease.

Long-term results after microsurgery for Cushing disease: experience with 426 primary operations over 35 years

OBJECTIVES

The aim of this paper was to demonstrate the long-term results following microsurgery in a single surgeon's continuous series of patients with Cushing disease (CD), to assess the influence of changes in surgical procedures, and to compare the results with those of other treatment modalities. In particular, preoperative diagnosis, tumor size, results of histological examination, and complications were considered.

METHODS

Between 1971 and 2004, 426 patients suffering from newly diagnosed CD underwent primary surgery. Pre-operative measures included clinical examination, endocrinological workup (testing of the hypothalamic-pituitary-adrenal axis, and 2- and 8-mg dexamethasone overnight suppression tests), sellar imaging (polytomography, computed tomography, and magnetic resonance [MR] imaging), and in patients with negative results on imaging studies, inferior petrosal sinus sampling. Follow-up examinations consisting of endocrinological workup, and imaging took place 1 week and 3 months after surgery and then at yearly intervals.

RESULTS

During microsurgery as first treatment, the adenoma finding rate was 86.6%. After selective adenomectomy, the remission rate was 75.9%, and this rate showed no improvement over the years. The best results were achieved in microadenomas confirmed on MR imaging or histopathological investigation. The recurrence rate (15%) and the complication rate (5.9%) declined over the years. If no adenoma was found, exploration of the sella turcica was performed in 45.6%, hypophysectomy in 3.5%, and hemihypophysectomy in 50.9% of these patients, leading to an early remission in 37.9%. In case of persistence or recurrence, further treatment (repeated operation, adrenalectomy, radio-therapy, or medical treatment) was used to control the disease.

CONCLUSIONS

Microsurgery remains the treatment of first choice in CD, even though no improvement in remission rates was observed over the years, because complication or remission rates for other treatment options are comparable or worse.

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.

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.

[Nelson's Syndrome: a case report]

The aim of this article is to present and discuss several aspects of the pathogenesis, the clinical, hormonal, and imaging diagnosis, and the treatment of Nelson's syndrome, based on a typical patient's report, in whom several therapeutic approaches were shown to be ineffective.

Evaluation and treatment of Cushing's syndrome

Cushing's syndrome results from sustained pathologic hypercortisolism caused by excessive corticotropin (ACTH) secretion by tumors in the pituitary gland (Cushing's disease, 70%) or elsewhere (15%), or by ACTH-independent cortisol secretion from adrenal tumors (15%). The clinical features are variable, and no single pattern is seen in all patients. Those features most specific for Cushing's syndrome include abnormal fat distribution, particularly in the supraclavicular and temporal fossae, proximal muscle weakness, wide purple striae, and decreased linear growth with continued weight gain in a child. Patients with characteristics of glucocorticoid excess should be screened with measurements of saliva or urine cortisol or dexamethasone suppression testing. The diagnosis of Cushing's syndrome should be followed by the measurement of plasma ACTH concentration to determine whether the hypercortisolism is ACTH-independent. In ACTH-dependent patients, bilateral inferior petrosal sinus sampling with measurement of ACTH before and after administration of ACTH-releasing hormone most accurately distinguishes pituitary from ectopic ACTH secretion. Surgical resection of tumor is the optimal treatment for all forms of Cushing's syndrome; bilateral adrenalectomy, medical treatment, or radiotherapy are sought in inoperable or recurrent cases. The medical treatment of choice is ketoconazole. The prognosis is better for Cushing's disease and benign adrenal causes of Cushing's syndrome than adrenocortical cancer and malignant ACTH-producing tumors.

Treatment of pituitary tumors: radiation

In this paper, the role of conventional radiotherapy and radiosurgery in the management of pituitary tumors is reviewed. After a short summary of the mechanism of action of irradiation therapy and the types of different irradiation techniques, the therapeutic effects and side effects are analyzed in patients with different types of pituitary tumors, including our own experience with conventional radiotherapy and radiosurgery in patients with acromegaly. Conventional fractionated radiotherapy has long been used to control growth and/or hormonal secretion of residual or recurrent pituitary tumors. However, patient selection for conventional radiotherapy still remains a controversial issue, because a number of potentially significant side effects, including hypopituitarism and other complications, have been described. Stereotactic radiotherapy/radiosurgery methods have several potential advantages over conventional radiotherapy, including their use in patients with residual or recurrent pituitary tumors who had previously been treated by conventional radiotherapy, but long-term follow-up data with these relatively new techniques are still limited.

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.

Stereotactic radiosurgery XVI: a treatment for previously irradiated pituitary adenomas

We report the use of stereotactic radiosurgery delivered through an adapted linear accelerator [stereotactic multiple arc radiation therapy (SMART)] for pituitary adenomas not cured by conventional therapy. All 21 patients had undergone conventional radiotherapy (45-50 Gy); 18 had also undergone prior surgery. This cohort comprised 13 patients with somatotrope adenomas, four with corticotrope adenomas, one with a lactotrope adenoma, and three with nonfunctioning pituitary adenomas (median follow-up: 33 months, range: 3-72 months). SMART has proven effective, safe, and rapidly acting. We observed an accelerated reduction in GH and IGF-I levels in acromegaly, with normalization of GH and IGF-I levels in 58%. Mean GH fell from 21.1 mU/liter to 7.9 mU/liter (7 ng/ml to 2.6 ng/ml, P < 0.01, median 25 months) faster than our predicted fall to 50% at 2 yr with conventional radiotherapy. Mean IGF-I fell from 624 ng/ml to 384 ng/ml (P < 0.001). Tumor growth was controlled in two of three nonfunctioning pituitary adenomas, and three of four corticotrope adenomas. There were no adverse effects from SMART. Notably there have been no visual sequelae or further loss of anterior pituitary function in this heavily pretreated group. Our data indicate that SMART is an effective complementary therapy for pituitary adenomas that have displayed a suboptimal response to conventional therapy including external irradiation.

Stereotactic radiosurgery for pituitary tumors

Pituitary adenomas frequently pose challenging clinical problems. Stereotactic radiosurgery (SRS) is one treatment option in selected patients. The purpose of this report is to identify the advantages and disadvantages of radiosurgery in cases of pituitary tumors to assess better its role in relation to other treatment. Methods for optimizing outcome are described. The author reviews several recent series to determine rates of growth control, endocrine response, and complications. In general, growth control is excellent, complications are very low, and reduction of excessive hormone secretion is fair. Depending on the clinical situation, SRS may be the treatment of choice in selected patients.

Clinical laboratory findings and results of therapy in 55 patients with Cushing's syndrome

In this study, 55 patients with Cushing's syndrome (CS) (50 female, 5 male; mean age 34 +/- 12.3 yr) who attended our clinics between the years 1983 and 2000 were retrospectively evaluated for clinical and laboratory features and modalities and results of therapy, due to a few similar studies over the last ten years. Cushing's disease was diagnosed in 39 patients (71%), adrenal adenoma in 13 patients (23.6%) and adrenal carcinoma in 3 patients (5.5%). Centripedal obesity, moon face, hypertension, hirsutism and purplish stria were the most frequent findings. Loss of normal serum F circadian rhythm was found in all patients with CS. The overnight 1 mg oral dexamethasone suppression test and low-dose dexamethasone suppression test (LDDST) yielded 100% and 100% diagnostic sensitivity for CS, respectively. Sensitivity and specivity of the high-dose dexamethasone suppression test (HDDST) in distinguishing Cushing's disease was found to be 82% and 100%, respectively. All of the patients with adrenal CS were not suppressed with HDDST. Sellar CT and/or MRI accurately identified the tumor in 58% of these patients. Recurrence was observed in 3 (11%) of the 28 patients with Cushing's disease, treated by transsphenoidal adenomectomy. Recurrence was diagnosed 1.5, 3 and 6 yr after the operation in these 3 patients. One patient had residue tumor. In our case series, bilateral adrenalectomy plus pituitary irradiation achieved the highest remission rate (100%) in Cushing's disease. In 2 out of 4 patients (50%) treated by left adrenalectomy associated with pituitary irradiation, recurrence was observed. Panhypopituitarism due to tumor apoplexy was observed in one of the patients with Cushing's disease. All of the patients with adrenal CS, the tumor was accurately localized with imaging methods before the operation. The appropriate operative procedure resulted in complete remission in patients with adrenal adenoma. Consequently, Cushing's disease was the most common form of CS. The overnight 1 mg oral DST and 24-h urine free F excretion (UFC) as screening tests, 2-day LDDST as diagnostic test and 2-day HDDST as differential diagnostic test were good studies. More successful outcomes have been achieved in treatment of Cushing's disease with the development of pituitary surgery in the recent years, as well as in our case series. Surgery is also curative for adrenal adenoma patients. Survival remains poor among carcinoma patients.

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

Object. The authors sought to analyze the long-term outcome of patients with Cushing disease who underwent gamma knife radiosurgery (GKS) as either an adjuvant or primary treatment.

Methods. Twenty-five patients with Cushing disease were treated by GKS and followed for more than 2.5 years (mean 5.3 years).

The overall results showed a complete response rate of 30%, a response rate of 85%, and a tumor control rate of 100%. Tumor size and radiation dose were the most important factors related to the treatment response. The complete response rate for microadenomas and small adenomas was significantly higher than that for macroadenomas. An 83.2% complete response rate was obtained using a maximum dose of more than 55 Gy and/or a margin dose of more than 40 Gy. Serum adrenocorticotropic hormone and cortisol levels were normalized in 35% of patients, decreased significantly in 60%, and decreased in 85%. Fifty-one of 85 characteristic signs and symptoms of Cushing disease improved without any side effects. The overall outcome was excellent in seven cases, good in six, fair in four, and poor in four cases; one patient died. The initial treatment was GKS in four patients, two of whom had a complete response and two of whom had a partial response. Hormone levels returned to normal in the patients in whom there was a complete response. The results in the six patients in whom Nelson syndrome was present were less favorable; the response rate was only 33%, although the control rate was 100%. Hormone levels decreased in two patients.

Conclusions. Gamma knife radiosurgery is safe and effective for the treatment of Cushing disease as an adjuvant or initial therapy when selective and accurate dose planning is performed.

Neurosurgical treatment of Nelson's syndrome

Total bilateral adrenalectomy remains the definitive procedure for cure in Cushing's disease. It is complicated by the development of Nelson's syndrome, the treatment of which remains troublesome. We report the long-term follow-up, median 17 yr (range, 8-22 yr), of 13 patients (3 males and 10 females) treated with pituitary surgery for Nelson's syndrome at a median age of 35 yr (range, 21-67 yr). The presence of a pituitary mass lesion necessitated neurosurgery in all. Preoperatively, the median plasma ACTH level was 664 pmol/liter (range, 92-3665 pmol/liter); this fell to 29 pmol/liter (range, <2 to 1124 pmol/liter) postoperatively (P < 0.0005). Cutaneous hyperpigmentation was reduced in all and resolved in 11 patients. The pituitary tumor bulk was clearly reduced in 12 patients. There was no perioperative mortality. No patient developed a visual field defect attributable to surgery. New anterior pituitary hormone deficiency occurred in seven patients, and permanent diabetes insipidus occurred in five patients. At latest follow-up, the median plasma ACTH is 73 pmol/liter (range, <2 to 7759 pmol/liter); six patients have levels of less than 44 pmol/liter and also have a resolution of their pigmentation and no evidence of a recurrence of a pituitary mass lesion. We conclude that pituitary surgery is an efficacious treatment for mass lesions associated with Nelson's syndrome, has long-term benefit with minimal side effects, and must be considered in the management of this distressing complication.

[ACTH pituitary adenomas: neurosurgical aspects]

We report our experience with 19 cases of ACTH secreting pituitary adenomas. They were microadenomas in 50% of the cases, coming with the typical picture of the Cushing syndrome. The ACTH adenoma associated with other types of hormones tend to show visual alterations. The treatment is often surgical using the transsphenoidal approach. The results were satisfactory in most of the cases. For those in which surgical cure was not reached, radiotherapy was indicated.

Classic and Recent Etiologies of Cushing??s Syndrome

Endogenous Cushing's syndrome can result from excess adrenocorticotropic hormone (ACTH; corticotropin) production by a pituitary adenoma (Cushing's disease) or by ectopic tumors secreting ACTH or corticotro- pin-releasing hormone (CRH). ACTH-independent Cushing's syndrome is caused by adrenocortical tumors or hyperplasias. Initial diagnosis is performed using 24-hour urinary free cortisol, low-dose dexamethasone tests, salivary cortisol, or night-time plasma cortisol values. A dexamethasone CRH test can discriminate between Cushing's syndrome and pseudo-Cushing's syndrome. If ACTH is elevated, combinations of high-dose dexamethasone tests, CRH/desmopressin tests, and pituitary magnetic resonance imaging can indicate a pituitary source. Discrimination from an ectopic ACTH tumor often requires inferior petrosal sinus sampling to confirm the ACTH source. If ACTH is low, adrenal computed tomography scan will identify the adrenal lesion(s) implicated. Some cortisol-producing adrenal tumors or, more frequently, bilateral macronodular hyperplasias, are under the control of aberrant membrane hormone receptors, or altered activity of eutopic receptors. The initial therapy of choice for patients with Cushing's disease is the selective transsphenoidal removal of the corticotroph adenoma; this induces remission in approximately 80% of patients, but long-term relapse occurs in up to 30% of these cases. The choice of second-line therapy remains controversial. Repeat surgery can be successful when residual tumor is detectable on magnetic resonance imaging, but carries a high risk of hypopituitarism. Bilateral adrenalectomy may be a better choice in patients without visible residual tumors, particularly in women desiring fertility. Radiotherapy combined with ketoconazole or radiosurgery was recently found effective, but longer-term evaluation of hypopituitarism and brain function is required. Current studies do not support the systematic use of prophylactic radiotherapy after bilateral adrenalectomy to decrease the risk of Nelson's syndrome; however, as soon as the residual tumor progresses, surgery and radiotherapy should be initiated. Various drugs which inhibit steroid synthesis (ketoconazole, metyrapone, aminoglutethimide, mitotane) are often effective for rapidly controlling hypercortisolism either in preparation for surgery, after unsuccessful removal of the etiologic tumor, or while awaiting the full effect of radiotherapy or more definitive therapy. Surgery is usually the treatment of choice for removal of cortisol-secreting adrenal tumors or ectopic ACTH/CRH-secreting tumors. The identification of aberrant adrenal receptors has recently allowed normalization of cortisol secretion by specific ligand receptor antagonists in limited cases of Cushing's syndrome secondary to bilateral macronodular adrenal hyperplasia. The long-term follow-up of patients treated for Cushing's syndrome should include the adequate replacement of glucocorticoids and other hormones, treatment of osteoporosis, and detection of long-term relapse of Cushing's syndrome.

Adrenocorticotropic hormone-producing pituitary tumors: 12- to 22-year follow-up after treatment with stereotactic radiosurgery

OBJECTIVE

To study retrospectively long-term outcomes of patients with adrenocorticotropic hormone-producing pituitary tumors that were treated with stereotactic Leksell gamma knife unit radiosurgery.

METHODS

Eighty-nine patients aged 5 to 67 years were treated between 1976 and 1985. Eighteen patients aged 18 to 68 years (mean age, 41 yr) were followed in detail. Fifteen patients were women. None had previously received conventional radiotherapy, but pituitary microsurgery had been performed in two patients, and one patient had had an adrenalectomy. In the remaining 15 patients, radiosurgery was the primary therapy.

RESULTS

Sixty-four patients had one stereotactic treatment, and 25 patients had two or more treatments. No complications were observed during treatment and the immediate follow-up period. At follow-up, 17 patients had died 1 to 20 years after the first treatment. No deaths were related to the treatment. In our 18 patients, the follow-up time after the first radiosurgical treatment was 12 to 22 years (mean follow-up period, 17 yr). Urinary cortisol levels gradually normalized in 83% of the patients. No recurrences were observed. Pituitary hormone insufficiencies developed in about two of every three patients and occurred even more than 10 years after treatment. Eight patients had transient hyperprolactinemia. The patients' vision and visual fields were unaffected, and none of them had signs of radiation-induced side effects such as brain tumors or brain necrosis.

CONCLUSION

Stereotactic radiosurgery is a safe and effective method in the treatment of patients with adrenocorticotropic hormone-producing pituitary tumors, and the effect of treatment is long-lasting. Stereotactic radiosurgery is mainly a complement to microsurgery because of its gradually appearing effect and the occurrence of pituitary insufficiency. New pituitary deficiencies may be found more than 10 years after treatment.

Management of Nelson's syndrome: observations in fifteen patients

OBJECTIVE

To analyse the results of different treatment modalities for Nelson's syndrome, which was defined as radiological evidence of a pituitary macroadenoma, fasting plasma ACTH levels of more than 200 pmol/l after stopping glucocorticoid substitution for at least 24 h in a patient who had undergone bilateral adrenalectomy for Cushing's disease.

DESIGN

The medical reports of all Nelson's patients known in our hospital were studied with regard to treatment modalities and result of treatment. Clinical remission of Nelson's syndrome was defined as a reduction of tumour size to a diameter of 10 mm or less and fasting plasma ACTH levels less than 200 pmol/l after stopping glucocorticoid substitution for at least 24 h.

PATIENTS

Fifteen women with Nelson's syndrome were studied. Bilateral adrenalectomy had been performed 1-29 years before Nelson's syndrome was diagnosed. Before adrenalectomy eight patients had undergone unsuccessful transsphenoidal pituitary surgery.

RESULTS

Eight patients were initially followed without surgical or radiotherapeutical intervention during 1-7 years. In seven of them, plasma ACTH levels and tumour volumes increased progressively during this rather short observation period, with development of extrasellar extension in four patients. In one of these patients, who was planned for elective pituitary surgery, massive pituitary haemorrhage occurred which was fatal despite emergency pituitary surgery. Elective pituitary surgery was performed in 11 patients, of whom three were operated twice. Clinical remission was documented in five patients in the first year after operation. In one patient postoperative MR-imaging revealed no residual tumour mass but the postoperative plasma ACTH level was still elevated. In another patient a residual intrasellar macroadenoma and an increased plasma ACTH level remained stable for 22 years. The remaining four patients received postoperative radiotherapy because of residual tumour masses. Of these patients, one had a clinical remission. In two others relatively small residual intrasellar tumour masses remain, with a fasting plasma ACTH level of more than 200 pmol/l in one of them. The fourth patient died of the consequences of progressive tumour growth. Radiotherapy was the only treatment in two patients and did not result in clinical remission. Tumour volumes and plasma ACTH levels at the time of diagnosis of Nelson's syndrome were positively correlated (r = + 0.61, P < 0.05). This correlation was stronger at the moment of decision of either pituitary surgery or radiotherapy (r = + 0.85, P < 0.001). At the end of the follow-up period the correlation between tumour volumes and plasma ACTH levels in the combined pituitary surgery and/or irradiation only group was + 0.77 (P < 0.001). In the pituitary surgery group tumour volumes before and after surgery were directly correlated (r = + 0.70, P < 0.05).

CONCLUSIONS

Our results demonstrate that pituitary surgery of Nelson's macroadenomas is more successful when Nelson's adenomas are relatively small. Pituitary surgery should be performed before extrasellar expansion of the tumour occurs in order to attain long lasting remissions. Pituitary irradiation should be performed postoperatively in all patients with residual tumour. Our data also illustrate that in patients with Nelson's syndrome, plasma ACTH levels can reliably be used as an indirect approximation for tumour volume.

S, Leite V, Canadas V. Tratamento medicamentoso dos tumores hipofisários. parte II: adenomas secretores de ACTH, TSH e adenomas clinicamente não-funcionantes

Este artigo revisa o potencial papel do tratamento medicamentoso para os adenomas hipofisários secretores de ACTH, TSH e aqueles clinicamente não-funcionantes (ACNF), Metirapona, mitotano e cetoconazol (preferível por causar menos efeitos colaterais) são as drogas mais eficazes no controle do hipercortisolismo, mas nenhuma delas supera a eficácia da cirurgia transesfenoidal (TSA). O tratamento medicamentoso da doença de Cushing está, portanto, melhor indicado para pacientes aguardando o efeito pleno da radioterapia ou, como alternativa para esta última, em casos de hipercortisolismo persistente após TSA, e para pacientes com rejeição ou limitações clínicas para a cirurgia. Outra indicação potencial seria em idosos com microadenomas ou pequenos macroadenomas, ou em casos associados a sela vazia. No que se refere aos adenomas secretores de TSH, os análogos somatostatínicos (SRIFa) proporcionam normalização dos hormônios tiroideanos em até 95% dos casos. Assim, eles podem se mostrar úteis em casos de insucesso da cirurgia ou como terapia primária de casos selecionados. Ocasionalmente, agonistas dopaminérgicos (DA), sobretudo a cabergolina, também podem ser eficazes. Em contraste, DA e SRIFa raramente induzem uma significante redução das dimensões dos ACNFs. Por isso, em pacientes com tais tumores, essas drogas devem ser principalmente consideradas diante de contra-indicações ou limitações clínicas para a cirurgia ou quando a cirurgia e a radioterapia tenham sido mal-sucedidas.

Stereotactic radiosurgery for pituitary adenomas

Pituitary adenoma is a radiosensitive disease and postoperative radiotherapy reduces the chance of relapse. Non-irradiated patients, followed in the modern era, suffer up to 20% five-year and up to 44% ten-year relapse. To some extent, predictors of relapse are available at the time of presentation or after surgery. Although conventionally fractionated radiotherapy has a very good track record with regard to controlling disease and safety in the modern age, there is considerable contemporary interest in the technique of radiosurgery (highly concentrated radiation therapy using stereotactic mapping). The usefulness of this technique in the treatment of pituitary adenoma is discussed in this review.

Treatment of pituitary-dependent Cushing's syndrome: long-term results of unilateral adrenalectomy followed by external pituitary irradiation compared to transsphenoidal pituitary surgery

BACKGROUND

The preferred treatment of Cushing's disease (CD) nowadays is transsphenoidal pituitary surgery (TPS). Prior to TPS, patients at the Leiden University Medical Centre were treated by unilateral adrenalectomy followed by external pituitary irradiation (UAPI). We report on long-term results of both UAPI and TPS and compare remission, relapse rates, and complications.

PATIENTS AND METHODS

A retrospective study was carried out on 130 patients with CD. Patients with pituitary macroadenoma were excluded. Eighty-six and 44 patients underwent UAPI and TPS, respectively. Of these patients, 85 and 41 were evaluable for long-term results.

RESULTS

Remission following UAPI and TPS was identical at 64% (54/85 and 27/41). Cumulative relapse was also comparable - 17% (9/54) and 22% (6/27), respectively, - for UAPI and TPS, although the mean follow-up periods were different - 21.4 years and 8.5 years, respectively. Cumulative disease-free survival curves after UAPI and TPS are identical until 5 years of follow-up, but diverge thereafter indicating more sustained remissions following UAPI (P = 0.17, Wilcoxon statistic). Pituitary dysfunction following UAPI (36%) and pituitary surgery (55%) likewise did not differ significantly. However, pituitary dysfunction was an immediate event after TPS, whereas it developed after a mean interval of 17.8 years following UAPI.Low-dose dexamethasone testing during follow-up had no value in predicting therapeutic outcome.

CONCLUSIONS

The results of unilateral adrenalectomy followed by external pituitary irradiation do not justify that this therapy is totally abandoned in favour of transsphenoidal pituitary surgery. Unilateral adrenalectomy followed by external pituitary irradiation is a valid therapeutic modality for the treatment of Cushing's disease, and could be considered as alternative to bilateral adrenalectomy and under some circumstances to transsphenoidal pituitary surgery.

Stereotactically delivered cranial radiation therapy: a ten-year experience of linac-based radiosurgery in the UK

In 1989, linear accelerator (linac)-based cranial stereotactic radiation therapy ('radiosurgery') was introduced in the UK at St Bartholomew's Hospital; a new, relocatable stereotactic frame was first used at the same time, allowing fractionated stereotactic radiotherapy. In the first decade of clinical practice using this technology, some 200 patients with blood vessel tumours/malformations have been treated, together with another 200 suffering from other conditions. The usefulness of this technique for cerebral arteriovenous malformations (AVM) has been demonstrated, and also a significant cure rate for AVM of >3 cm diameter (which is larger than for those previously reported after treatment on the gamma unit), albeit attended by a higher complication rate. The epilepsy associated with AVM is much improved by successful radiotherapy. The usefulness of radiosurgery for glomus tumours has been confirmed and new data published on the efficacy of the technique for haemangioblastoma, with new radiation therapy strategies designed for patients with von Hippel-Lindau disease. The acoustic neuroma treatment results have included improvements in hearing (a result not reported in the gamma unit literature), which are ascribed to the lower internal dose gradient within the target volume. Fractionation will, it is argued, also lead to sparing of the special sensory cochlear nerve. The risks of radiosurgery to the brainstem for chordoma of the mid-clivus are reduced by using a 'spacer' technique for the prepontine space. For meningiomas involving the cavernous sinus, conventionally fractionated radiotherapy is recommended when the meningeal base diameter exceeds 3.0 cm and radiosurgery (utilizing fractionation where appropriate) is advised for smaller lesions. Thus far, radiosurgery indications for pituitary adenomas have been restricted to recurrences after conventional radiotherapy, usually those in the cavernous sinus. In therapy for recurrent craniopharyngioma, it is argued that fractionation delivered via the relocatable frame will be important, particularly when the disease envelops the optic chiasma. For semicystic/semisolid craniopharyngiomas, the stereotactic delivery of colloidal yttrium-90 into a cystic element is useful, while stereotactic radiosurgery is delivered to the solid component. Staff at this centre consider that radiosurgery for low-grade gliomas, perhaps as boost therapy after conventional fractionation, is worthy of more research. We have been extremely selective in the use of radiosurgery for brain metastases (2% of patients, compared with about 30% in some Gamma Knife units), but future indications may become broader, probably using it as a booster technique after whole-brain conventionally-fractionated radiotherapy. Positron emission tomography scanning, co-registered with magnetic resonance imaging, allows the 'boost' concept in radiosurgery to become a sophisticated and accurate reality. Post-radiosurgical sequelae have been placed within a standard framework classification. New observations are being made with regard to subacute reactions: late-responding intrinsic and extra-axial tumours may swell in the subacute period, prior to shrinkage, and be attended by symptomatic surrounding brain oedema.