External Beam Radiation Therapy and Stereotactic Radiosurgery for Pituitary Adenomas

Consensus guideline for the diagnosis and management of pituitary adenomas in childhood and adolescence: Part 2, specific diseases

Pituitary adenomas are rare in children and young people under the age of 19 (hereafter referred to as CYP) but they pose some different diagnostic and management challenges in this age group than in adults. These rare neoplasms can disrupt maturational, visual, intellectual and developmental processes and, in CYP, they tend to have more occult presentation, aggressive behaviour and are more likely to have a genetic basis than in adults. Through standardized AGREE II methodology, literature review and Delphi consensus, a multidisciplinary expert group developed 74 pragmatic management recommendations aimed at optimizing care for CYP in the first-ever comprehensive consensus guideline to cover the care of CYP with pituitary adenoma. Part 2 of this consensus guideline details 57 recommendations for paediatric patients with prolactinomas, Cushing disease, growth hormone excess causing gigantism and acromegaly, clinically non-functioning adenomas, and the rare TSHomas. Compared with adult patients with pituitary adenomas, we highlight that, in the CYP group, there is a greater proportion of functioning tumours, including macroprolactinomas, greater likelihood of underlying genetic disease, more corticotrophinomas in boys aged under 10 years than in girls and difficulty of peri-pubertal diagnosis of growth hormone excess. Collaboration with pituitary specialists caring for adult patients, as part of commissioned and centralized multidisciplinary teams, is key for optimizing management, transition and lifelong care and facilitates the collection of health-related quality of survival outcomes of novel medical, surgical and radiotherapeutic treatments, which are currently largely missing.

Early Versus Delayed Fractionated Stereotactic Radiotherapy for Nonfunctioning Pituitary Adenoma

BACKGROUND

Fractionated stereotactic radiotherapy (FSRT) is a common modality used to treat pituitary adenomas with good control rates. It is not known whether FSRT should be performed early or delayed until progression occurs. We compared FSRT in treating nonfunctional pituitary adenomas (NFPA) as an adjuvant (ADJ) or on-progression (PRG) therapy.

METHODS

A retrospective review of patients who underwent FSRT for an NFPA between January 2004 and December 2022 at a single institution was performed. We compared endocrinologic, ophthalmologic, and radiographic outcomes in FSRT delivered as ADJ and PRG treatment.

RESULTS

Seventy-five patients were analyzed, with a median follow-up of 53 months. FSRT was administered to 35 and 40 patients as ADJ and PRG, with a median time to treatment of 5.5 and 40 months, respectively. The tumor control rate was 94.3% for ADJ and 95.0% for PRG. Treatment resulted in 4 (11.4%) versus 7 (17.5%) new endocrinopathies and 2 (5.7%) versus 1 (2.5%) new visual deficits for ADJ versus PRG. A survival analysis of time to new endocrinopathy showed no difference between the 2 cohorts. The median time from surgery to new endocrinopathy was significantly different between ADJ and PRG, at 15.5 and 102.0 months, respectively.

CONCLUSIONS

FSRT is effective in treating NFPA for residual and progressive tumors, with excellent tumor control rates and a low risk of developing new endocrinopathies and visual deficits. Delaying treatment delayed the development of new endocrinopathies, suggesting that observation with FSRT on tumor progression may delay the onset of hypopituitarism and maintain similar effectiveness in tumor control.

Modern Radiation Oncology: From IMRT to Particle Therapy—Present Status and the Days to Come

There has been tremendous technological development in the field of radiation oncology, mainly during the last few decades. Parallel advancements in imaging and accelerator technologies have contributed significantly to the same. Present-day radiation therapy is aimed at precision, in terms of physical accuracy of both its planning and delivery. This has been made possible by improvements in defining the target (use of various radiological and functional imaging modalities), advanced radiotherapy planning methods (intensity-modulated radiation therapy and recent emergence of particle therapy), and robust verification techniques (image-guided radiation therapy). These developments have enabled delivery of adequate tumoricidal doses conforming to the target, thereby improving disease control with reduced normal tissue toxicity in a wide range of malignancies. Elucidation of molecular pathways determining radioresistance or systemic effects of radiotherapy and strategies for therapeutic manipulation of the same are also being explored. Overall, we look forward to ensuring basic radiotherapy access to all patients, and precision radiation therapy to appropriate candidates (triaged by disease anatomy or biology and associated cost-effectiveness).

Characteristics and overall survival in pediatric versus adult pituitary adenoma: a National Cancer Database analysis

OBJECTIVE

Pituitary adenomas in the pediatric population are extremely rare, resulting in limited information in the literature on these patients. In this study, data from the National Cancer Database (NCDB) to compare pituitary adenoma clinical presentations, treatment management patterns, and overall survival between pediatric and adult patients.

METHODS

The NCDB was queried for all cases of histologically confirmed pituitary adenoma treated between 2004 and 2015. Patients were primarily stratified as either pediatric (< 18 years) or adult (≥ 18 years). Patient demographics/socioeconomics and resulting outcomes were then compared.

RESULTS

1893 pediatric and 77,993 adult patients with pituitary adenomas were evaluated. Average tumor size for pediatric and adult patients was 13.6 ± 13.2 mm and 20.1 ± 13.1 mm, respectively (p < 0.001). Pediatric patients were more likely to undergo gross total resection, less likely to receive adjuvant radiation, more likely to receive medical therapy, more likely to undergo active surveillance, and exhibited improved 5-year and 10-year overall survival (OS) (all p < 0.001). Temporal analysis demonstrated a significant increase in endoscopic approach over time (from 48 to 65%) in the pediatric population (R² = 0.722, p = 0.03). On univariate analysis in the pediatric population, African American race compared to Caucasians (HR: 5.85, 95% CI 1.79-19.2, p < 0.003), patients with government insurance compared to those with private insurance (HR: 5.07, 95% CI 1.31-19.6, p < 0.02) and uninsured patients compared to those with private insurance (HR: 14.4, 95% CI 2.41-86.5, p < 0.003) were associated with decreased OS. Lastly, patients who underwent GTR had improved OS compared to those who underwent subtotal resection (HR: 0.08, 95% CI 0.008-0.93, p < 0.04) in the pediatric population.

CONCLUSIONS

Compared to adults, children with pituitary adenomas more commonly underwent GTR, less frequently underwent adjuvant radiotherapy, more frequently underwent medical management and active surveillance, and had improved survival. Temporal analysis demonstrated increasing utilization of the endoscopic approach for surgical treatment of pediatric and adult pituitary adenoma patients.

LEVEL OF EVIDENCE

Level III.

Pituitary gigantism: a rare learning opportunity

INTRODUCTION

Pituitary gigantism is a rare but significant paediatric condition with complexities surrounding diagnosis and management. Transsphenoidal surgery (TSS) is the treatment of choice; however, medical treatment is often considered as adjuvant therapy.

CASE

A 10½ -year-old boy presented with tall stature and a height velocity of 11 cm/year. His height was 178.7 cm (+5.8 SD above mean) and insulin-like growth factor-1 (IGF-1) was elevated. An oral glucose tolerance test demonstrated non-suppression of growth hormone (GH). Initial contrast MRI was inconclusive, but C-11 methionine functional positron emission tomography CT identified a 6 mm pituitary microadenoma. A multidisciplinary team clinic held with the family allowed discussion about medical and surgical treatment options. Due to a number of factors including the patient's young age, prepubertal status, a wish to allow him to settle into his new high school and his desire to reach a final height taller than his father's height, it was decided to try medical therapy first with a somatostatin analogue. Pubertal induction was also commenced and bilateral epiphysiodesis surgery performed. Initial response to octreotide was positive; however, 4 months into therapy his IGF-1 was climbing and a repeat GH profile was not fully suppressed. The patient therefore proceeded to have successful TSS excision of the adenoma.

CONCLUSION

Rare cases such as this require sharing of knowledge and expertise, so the best possible care is offered. It is often necessary to work across sites and disciplines. Each case requires an individual approach tailored to the patient and their family.

Factors Associated with and Temporal Trends in the Use of Radiation Therapy for the Treatment of Pituitary Adenoma in the National Cancer Database

Objective  Radiation therapy represents an uncommon but important component of treatment plans for some pituitary adenomas (PAs). Although radiation therapy has been used to treat pituitary adenomas for over a century, general trends in the usage of radiation therapy for this purpose have not been reviewed. Additionally, there are few large studies evaluating how radiation therapy is used for the treatment of these benign tumors. Investigating these trends and identifying any variations in radiation therapy utilization would help to better inform treatment decisions and improve patient outcomes. Design  Present study is a retrospective analysis of cases using the National Cancer Database. Setting  The research was organized at a tertiary academic medical center. Participants  Patients were diagnosed with pituitary adenoma between 2004 and 2014 within the National Cancer Database (NCDB). Methods  Temporal trends in the usage of radiation therapy to treat pituitary adenoma were analyzed through a retrospective analysis of 77,142 pituitary adenoma cases from the NCDB between 2004 and 2014. Univariate and multivariate analyses were to examine the relationship between patient, tumor, and treatment factors, and the incorporation of radiation therapy into the treatment of pituitary adenomas. We adjusted for potential confounders such as age, sex, race, comorbidity score, facility type, and year of diagnosis. Results  A total of 77,142 patients met inclusion criteria. Inclusion of radiation therapy in pituitary adenoma treatment was 8.0% in 2004 and steadily declined to a low of 3.1% in 2014. Overall, patients were less likely to receive radiation for their pituitary adenoma over time ( p  < 0.001). Similarly, patients were found to be less likely to receive any type of treatment for PA over time ( p  < 0.001). Multivariable evaluation found patients who were female, between 54 and 64 years of age, or treated at either a Comprehensive Community Cancer Program or an Integrated Network Cancer Program were more likely to receive radiation as part of their pituitary adenoma treatment ( p  < 0.001, odds ratio [OR] = 2.01, confidence interval [CI]: 1.54-2.63; p  < 0.001, OR = 1.84, CI: 1.38-2.44, respectively). Patients were less likely to receive radiation for their PA if they were African American ( p  < 0.001, OR = 0.81, CI: 0.72-0.91). Logistic regression also identified a progressive increase in the likelihood of receiving radiation after a PA diagnosis with increasing tumor size starting with microscopic tumors, peaking at 4 to 5 cm ( p  < 0.001; OR = 15.57; CI: 12.20-19.87). Conclusion  In this sample of pituitary adenoma patients treated at NCDB institutions between 2004 and 2014, we found a steady decline in the incorporation of radiation therapy in treatment, as well as in the use of any type of intervention for PA treatment, suggesting a rise in noninterventional observation of PA.

Postoperative expression of Cushing disease in a young male: metamorphosis of silent corticotroph adenoma?

SUMMARY

Silent corticotroph adenoma (SCA) is an unusual type of nonfunctioning pituitary adenoma (NFA) that is silent both clinically and biochemically and can only be recognized by positive immunostaining for ACTH. Under rare circumstances, it can transform into hormonally active disease presenting with severe Cushing syndrome. It might often produce diagnostic dilemma with difficult management issue if not thoroughly investigated and subtyped accordingly following surgery. Here, we present a 21-year-old male who initially underwent pituitary adenomectomy for presumed NFA with compressive symptoms. However, he developed recurrent and invasive macroadenoma with severe clinical as well as biochemical hypercortisolism during post-surgical follow-up. Repeat pituitary surgery was carried out urgently as there was significant optic chiasmal compression. Immunohistochemical analysis of the tumor tissue obtained on repeat surgery proved it to be an aggressive corticotroph adenoma. Though not cured, he showed marked clinical and biochemical improvement in the immediate postoperative period. Anticipating recurrence from the residual tumor, we referred him for cyber knife radio surgery.

LEARNING POINTS

Pituitary NFA commonly present with compressive symptoms such as headache and blurred vision. Post-surgical development of Cushing syndrome in such a case could be either drug induced or endogenous. In the presence of recurrent pituitary tumor, ACTH-dependent Cushing syndrome indicates CD. Rarely a SCA presenting initially as NFA can transform into an active corticotroph adenoma. Immunohistochemical marker for ACTH in the resected tumor confirms the diagnosis.

Management of Nonfunctioning Recurrent Pituitary Adenomas

Pituitary adenomas are typically slow-growing benign tumors. However, 50% to 60% of tumors progress following subtotal resection and up to 30% recur after apparent complete resection. Options for treatment of recurrent pituitary adenomas include repeat surgical resection, radiation therapy, and systemic therapies. There is no consensus approach for the management of recurrent pituitary adenomas. This article reviews the natural history of recurrent adenomas and emerging biomarkers predictive of clinical behavior as well as the outcomes associated with the various treatment modalities for these challenging tumors, with an emphasis on the surgical treatment.

Upfront Gamma Knife radiosurgery for Cushing's disease and acromegaly: a multicenter, international study

OBJECTIVE

Gamma Knife radiosurgery (GKS) is typically used after failed resection in patients with Cushing's disease (CD) and acromegaly. Little is known about the upfront role of GKS for patients with CD and acromegaly. In this study, the authors examine the outcome of upfront GKS for patients with these functioning adenomas.

METHODS

An international group of 7 Gamma Knife centers sent pooled data from 46 patients (21 with CD and 25 with acromegaly) undergoing upfront GKS to the coordinating center of the study for analysis. Diagnosis was established on the basis of clinical, endocrine, and radiological studies. All patients were treated on a common radiosurgical platform and longitudinally followed for tumor control, endocrine remission, and hypopituitarism. Patients received a tumor median margin dose of 25 Gy (range 12-40.0 Gy) at a median isodose of 50%.

RESULTS

The median endocrine follow-up was 69.5 months (range 9-246 months). Endocrine remission was achieved in 51% of the entire cohort, with 28% remission in acromegaly and 81% remission for those with CD at the 5-year interval. Patients with CD achieved remission earlier as compared to those with acromegaly (p = 0.0005). In patients post-GKS, the pituitary adenoma remained stable (39%) or reduced (61%) in size. Hypopituitarism occurred in 9 patients (19.6%), and 1 (2.2%) developed third cranial nerve (CN III) palsy. Eight patients needed further intervention, including repeat GKS in 6 and transsphenoidal surgery in 2.

CONCLUSIONS

Upfront GKS resulted in good tumor control as well as a low rate of adverse radiation effects in the whole group. Patients with CD achieved a faster and far better remission rate after upfront GKS in comparison to patients with acromegaly. GKS can be considered as an upfront treatment in carefully selected patients with CD who are unwilling or unable to undergo resection, but it has a more limited role in acromegaly.

[Pituitary adenomas]

Despite characteristic symptoms the diagnosis of clinically relevant pituitary adenomas is often delayed until an advanced stage due to the rarity of the disease. The typical clinical manifestations are presented in this review article. The recent discovery of the USP8 mutation in Cushing's disease and of X‑linked acrogigantism (X-LAG) syndrome in early onset gigantism were milestones in the search for the molecular etiology of pituitary adenomas. The triad of endocrinological, radiological and ophthalmological diagnostics are the main pillars for the diagnostic work-up of pituitary adenomas. The standard treatment modalities, which include surgery, medical treatment and irradiation, have been further developed and refined. For transsphenoidal excision of pituitary adenomas, microsurgery and endoscopy are two equivalent surgical techniques with relatively few complications. Surgery represents the first-line treatment of pituitary adenomas. Prolactinomas are an exception as the medical treatment with dopamine agonists is highly efficient. Nowadays, new medical treatment options are available for acromegaly and Cushing's disease and are used for second-line treatment. The alkylating chemotherapeutic agent temozolomide is used for the first-line chemotherapy of rare aggressively growing pituitary adenomas. Irradiation is indicated if surgical and medical treatment options are insufficiently successful. Stereotactic one-stage irradiation (radiosurgery) is especially suitable for well-demarcated invasive residual or recurrent adenomas in the cavernous sinus. A new development is hypofractionated radiosurgery for protection of structures at risk. Fractionated irradiation is necessary with large radiation volumes and for pituitary adenomas with a close proximity to the optic tract.

Pediatric Pituitary Adenoma: Case Series, Review of the Literature, and a Skull Base Treatment Paradigm

Background  Pediatric pituitary adenoma is a rare skull base neoplasm, accounting for 3% of all intracranial neoplasms in children and 5% of pituitary adenomas. Compared with pituitary tumors in adults, secreting tumors predominate and longer disease trajectories are expected due to the patient age resulting in a natural history and treatment paradigm that is complex and controversial. Objectives  The aims of this study were to describe a large, single-institution series of pediatric pituitary adenomas with extensive long-term follow-up and to conduct a systematic review examining outcomes after pituitary adenoma surgery in the pediatric population. Methods  The study cohort was compiled by searching institutional pathology and operative reports using diagnosis and site codes for pituitary and sellar pathology, from 1956 to 2016. Systematic review of the English language literature since 1970 was conducted using PubMed, MEDLINE, Embase, and Google Scholar. Results  Thirty-nine surgically managed pediatric pituitary adenomas were identified, including 15 prolactinomas, 14 corticotrophs, 7 somatotrophs, and 4 non-secreting adenomas. All patients underwent transsphenoidal resection (TSR) as the initial surgical treatment. Surgical cure was achieved in 18 (46%); 21 experienced recurrent/persistent disease, with secondary treatments including repeat surgery in 10, radiation in 14, adjuvant pharmacotherapy in 11, and bilateral adrenalectomy in 3. At the last follow-up (median 87 months, range 3-581), nine remained with recurrent/persistent disease (23%). Thirty-seven publications reporting surgical series of pediatric pituitary adenomas were included, containing 1,284 patients. Adrenocorticotropic hormone (ACTH)-secreting tumors were most prevalent (43%), followed by prolactin (PRL)-secreting (37%), growth hormone (GH)-secreting (12%), and nonsecreting (7%). Surgical cure was reported in 65%. Complications included pituitary insufficiency (23%), permanent visual dysfunction (6%), chronic diabetes insipidus (DI) (3%), and postoperative cerebrospinal fluid (CSF) leak (4%). Mean follow-up was 63 months (range 0-240), with recurrent/persistent disease reported in 18% at the time of last follow-up. Conclusion  Pediatric pituitary adenomas are diverse and challenging tumors with complexities far beyond those encountered in the management of routine adult pituitary disease, including nuanced decision-making, a technically demanding operative environment, high propensity for recurrence, and the potentially serious consequences of hypopituitarism with respect to fertility and growth potential in a pediatric population. Optimal treatment requires a high degree of individualization, and patients are most likely to benefit from consolidated, multidisciplinary care in highly experienced centers.

Fractionated Stereotactic Radiotherapy for Pituitary Adenomas: Single-Center Experience in 75 Consecutive Patients

BACKGROUND

Early results of postoperative fractionated stereotactic radiotherapy (FSRT) for functional and nonfunctional pituitary adenomas appear promising, but the majority of available evidence draws from small series with insufficient follow-up data to draw meaningful conclusions.

OBJECTIVE

To evaluate the long-term outcomes of a large series of patients undergoing FSRT for both functional and nonfunctional pituitary adenomas with the Novalis system (BrainLAB, Heimstetten, Germany).

METHODS

Chart data for 75 consecutive patients undergoing FSRT for a pituitary tumor (21 functional and 54 nonfunctional adenomas) at our institution between January 2004 and June 2013 were reviewed.

RESULTS

Radiographic progression-free survival was 100% over a mean of 47.8 months of radiographic follow-up (range, 12.0-131.2 months). Hormonal normalization was seen in 69.2% of patients with functional adenomas after FSRT, whereas 30.8% experienced partial hormonal control. Mild, grade I acute adverse effects were observed during radiotherapy treatment in 36 patients (48%), and objective, persistent worsening of vision occurred in a single patient (1.5%) after FSRT. New hormonal deficits were seen in 28.0% of patients after FSRT. Radiographic responses were inversely related to tumor volume.

CONCLUSION

FSRT delivers radiographic and functional outcomes similar to those seen with stereotactic radiosurgery and conventional radiotherapy with less resultant toxicity. FSRT is most beneficial for smaller tumors (those <3 cm in diameter).

ABBREVIATIONS

EBRT, external beam radiotherapyFSRT, fractionated stereotactic radiotherapyOR, odds ratioPTV, planning target volumeSRS, stereotactic radiosurgery.

Prognostic significance of corticotroph staining in radiosurgery for non-functioning pituitary adenomas: a multicenter study

Silent corticotroph staining pituitary adenoma (SCA) represents an uncommon subset of Non-Functioning adenomas (NFAs), hypothesized to be more locally aggressive. In this retrospective multicenter study, we investigate the safety and effectiveness of Stereotactic Radiosurgery (SRS) in patients with SCA compared with other non-SCA NFA's. Eight centers participating in the International Gamma-Knife Research Foundation (IGKRF) contributed to this study. Outcomes of 50 patients with confirmed SCAs and 307 patients with confirmed non-SCA NFA's treated with SRS were evaluated. Groups were matched. SCA was characterized by a lack of clinical evidence of Cushing disease, yet with positive immunostaining for corticotroph. Median age was 55.2 years (13.7-87). All patients underwent at least one trans-sphenoidal tumor resection prior to SRS. SRS parameters were comparable as well. Median follow-up 40 months (6-163). Overall tumor control rate (TCR) 91.2% (n = 280). In the SCA group, TCR were 82% (n = 41) versus 94.1% (n = 289) for the control-NFA (p = 0.0065). The SCA group showed a significantly higher incidence of new post-SRS visual deficit (p < 0.0001) assigned to tumor progression and growth, and post-SRS weakness and fatigue (p < 0.0001). In univariate and multivariate analysis, only the status of silent corticotroph staining (p = 0.005, p = 0.009 respectively) and margin dose (p < 0.0005, p = 0.0037 respectively) significantly influenced progression rate. A margin dose of ≥17 Gy was noted to influence the adenoma progression rate in the entire cohort (p = 0.003). Silent corticotroph staining represents an independent factor for adenoma progression and hypopituitarism after SRS. A higher margin dose may convey a greater chance of TCR.

Paediatric pituitary adenomas: a decade of change

Pituitary adenomas, although rare in the paediatric age range and mostly benign, represent very challenging disorders for diagnosis and management. The recent identification of genetic alterations in young individuals with pituitary adenomas has broadened the scope of molecular investigations and contributed to the understanding of mechanisms of tumorigenesis. Recent identification of causative mutations of genes such as GNAS, PRKAR1A, MEN1 and AIP has introduced the concept of molecular screening of young apparently healthy family members. Population-based studies have reported a significantly higher number of affected subjects and genetic variations than expected. Radiological techniques have advanced, yet many microadenomas remain undetectable on scanning. However, experience with transsphenoidal and endoscopic pituitary surgery has led to higher rates of cure. Prolactinomas, corticotroph and somatotroph adenomas remain the most prevalent, with each diagnosis presenting its own challenges. As paediatric pituitary adenomas occur very infrequently within the paediatric age range, paediatric endocrine units cannot provide expert management in isolation. Consequently, close co-operation with adult endocrinology colleagues with experience of pituitary disease is strongly recommended.

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.

Effect of treatment modality on the hypothalamic-pituitary function of patients treated with radiation therapy for pituitary adenomas: hypothalamic dose and endocrine outcomes

BACKGROUND

Both fractionated external beam radiotherapy and single fraction radiosurgery for pituitary adenomas are associated with the risk of hypothalamic-pituitary (HP) axis dysfunction.

OBJECTIVE

To analyze the effect of treatment modality (Linac, TomoTherapy, or gamma knife) on hypothalamic dose and correlate these with HP-axis deficits after radiotherapy.

METHODS

Radiation plans of patients treated post-operatively for pituitary adenomas using Linac-based 3D-conformal radiotherapy (CRT) (n = 11), TomoTherapy-based intensity modulated radiation therapy (IMRT) (n = 10), or gamma knife stereotactic radiosurgery (n = 12) were retrospectively reviewed. Dose to the hypothalamus was analyzed and post-radiotherapy hormone function including growth hormone, thyroid stimulating hormone, adrenocorticotropic hormone, prolactin, and gonadotropins (follicle stimulating hormone/luteinizing hormone) were assessed.

RESULTS

Post-radiation, 13 of 27 (48%) patients eligible for analysis developed at least one new hormone deficit, of which 8 of 11 (72%) occurred in the Linac group, 4 of 8 (50%) occurred in the TomoTherapy group, and 1 of 8 (12.5%) occurred in the gamma knife group. Compared with fractionated techniques, gamma knife showed improved hypothalamic sparing for DMax Hypo and V12Gy. For fractionated modalities, TomoTherapy showed improved dosimetric characteristics over Linac-based treatment with hypothalamic DMean (44.8 vs. 26.8 Gy p = 0.02), DMax (49.8 vs. 39.1 Gy p = 0.04), and V12Gy (100 vs. 76% p = 0.004).

CONCLUSION

Maximal dosimetric avoidance of the hypothalamus was achieved using gamma knife-based radiosurgery followed by TomoTherapy-based IMRT, and Linac-based 3D conformal radiation therapy, respectively.

Results of gamma knife surgery for Cushing's disease

OBJECT

Cushing's disease is a challenging neuroendocrine disorder. Although resection remains the primary treatment option for most patients, the disease persists if there is residual or recurrent tumor. Stereotactic radiosurgery has been used to treat patients with persistent Cushing's disease after a prior resection. The authors report on the long-term risks and benefits of radiosurgery for Cushing's disease.

METHODS

A retrospective review of a prospectively collected database of radiosurgery patients was undertaken at the University of Virginia. All patients with Cushing's disease treated with Gamma Knife surgery (GKS) were identified. Those without at least 12 months of clinical and radiological follow-up were excluded from this analysis. Rates of endocrine remission, tumor control, and adverse events were assessed. Statistical methods were used to identify favorable and unfavorable prognostic factors.

RESULTS

Ninety-six patients with the required follow-up data were identified. The mean tumor margin dose was 22 Gy. The median follow-up was 48 months (range 12-209.8 months). At the last follow-up, remission of Cushing's disease occurred in 70% of patients. The median time to remission among all patients was 16.6 months (range 1-165.7 months). The median time to remission in those who had temporarily stopped taking ketoconazole at the time of GKS was 12.6 months, whereas it was 21.8 months in those who continued to receive ketoconazole (p < 0.012). Tumor control was achieved in 98% of patients. New loss of pituitary function occurred in 36% of patients. New or worsening cranial neuropathies developed in 5 patients after GKS, with the most common involving cranial nerves II and III.

CONCLUSIONS

Gamma Knife surgery offers a high rate of tumor control and a reasonable rate of endocrine remission in patients with Cushing's disease. The cessation of cortisol-lowering medications around the time of GKS appears to result in a more rapid rate of remission. Delayed hypopituitarism and endocrine recurrence develop in a minority of patients and underscore the need for long-term multidisciplinary follow-up.