The clinical significance of MIB-1 labeling index in pituitary adenomas

A current perspective of pituitary adenoma MRI characteristics: a review

INTRODUCTION

MR imaging is an essential and fundamental tool in the diagnosis, management, and follow-up of patients with pituitary adenomas (PAs). Recent advances have continued to enhance the usefulness of this imaging modality.

AREAS COVERED

This article focuses on signal intensity patterns of PAs and associated clinical characteristics, vertical extension patterns, and cavernous sinus invasion with a special focus on the clinical implications that arise. A search using Medline and Google Scholar was conducted using different combinations of relevant keywords, giving preference to recent publications.

EXPERT OPINION

A higher proportion of GH-secreting PAs are hypointense on T2 weighted images compared to other tumor subtypes. Hypointense tumors are generally smaller compared to hyperintense ones, and among the GH-secreting subgroup, a better response to somatostatin analogue treatment was noted together with an association for a densely granulated pattern. Nonfunctional PAs show a predilection to extend upwards while GH-secreting PAs and prolactinomas show a predominantly inferior extension growth pattern. Further studies to better understand the mechanisms responsible for this behavior are anticipated. Further development, refining and validation of predictive scoring systems for tumor behavior might be useful adjuncts in the management of patients with PAs.

The Past, Present, and Future Statuses of Formerly Classified "Atypical Pituitary Adenomas": A Clinicopathological Assessment of 101 Cases in a Cohort of More than 1,000 Pure Endoscopically Treated Patients in Single Center

Objective  This study was aimed to assess the clinical aggressiveness of pituitary neoplasms that were previously defined as atypical adenomas. Methods  A total of 1,042 pituitary adenomas were included in the study and 101 of them were diagnosed as atypical adenoma. Demographic characteristics, radiological evaluations, and clinical information were obtained from a computer-based patient database. Cases were categorized as atypical or typical using the criteria listed in 2004 Classification of Tumors of Endocrine Organs. Results  The cure and reoperation rates did not show any statistically significant difference between the typical and atypical adenomas. However, a higher K _i -67 labeling index was found to be associated with a higher rate of reoperation ( p  = 0.008) in atypical adenomas. Of note, cavernous sinus invasion or parasellar extension was found to be associated with lower cure rates in patients with atypical pituitary adenomas ( p  < 0.001 and p  = 0.001, respectively). Conclusion  Although atypical pituitary adenomas are known to be more invasive, this study demonstrated that the reoperation and cure rates are the same for typical and atypical adenomas. Our findings advocate for omitting the use of atypical adenoma terminology based solely on pathological evaluation. As stated in the 4th edition of the World Health Organization (WHO) classification, accurate tumor subtyping, evaluation of proliferation by means of mitotic count and K _i -67 labeling index, and radiological and intraoperative assessments of tumor invasion should be taken into consideration in the management of such neoplasms.

Ki-67 labeling index and expression of p53 are non-predictive for invasiveness and tumor size in functional and nonfunctional pituitary adenomas

BACKGROUND

It is still controversial whether an increased proliferation index is correlated with the tumor invasiveness of pituitary adenomas. A homogeneous large monocentric series of pituitary adenomas was retrospectively analyzed. The correlation between the proliferation indices (Ki-67 and p53 expression levels) and invasiveness and size of pituitary adenomas was investigated in primary operated and recurrent adenomas.

METHOD

Four hundred thirty-nine patients after resection of pituitary adenomas were retrospectively included (43 recurrent tumors, 196 null cell adenomas, 86 somatotroph adenomas, 55 corticotroph adenomas, 55 prolactinomas, 4 thyreotroph adenomas). The maximum tumor diameter and tumor invasiveness in Knosp grading were assessed and Ki-67 and p53 immunostaining was performed. The role of invasiveness was evaluated using a cumulative odds ordinal logistic regression. For calculating the effect of tumor size, a one-way analysis of variance (ANOVA) was conducted.

RESULTS

Overall and in the subgroups, no significant correlation between proliferation indices and mean tumor diameter was found. No significant predictive expression value of Ki-67 and p53 on tumor invasiveness and in recurrent tumors could be demonstrated. There was a tendency that Ki-67 LI and p53 LI are higher in recurrent corticotroph adenomas and lactotroph adenomas but values did not reach the significant level.

CONCLUSION

Invasive character of pituitary adenomas is neither correlated with increased Ki-67 LI nor with increased p53 expression. Proliferation parameters are independent from adenoma size at initial presentation. The partly elevated expression of Ki-67 in recurrent tumors underlines the clinical importance of the marker.

The Prognostic Roles of the Ki-67 Proliferation Index, P53 Expression, Mitotic Index, and Radiological Tumor Invasion in Pituitary Adenomas

The fourth edition of the World Health Organization (WHO) classification of pituitary tumors recommended evaluation of tumor proliferation and invasion to identify aggressiveness. We aimed to assess the prognostic roles of the Ki-67 proliferation index, mitotic index, P53 expression, and cavernous sinus invasion in pituitary adenomas (PAs). Among the 601 patients who underwent transnasal/transsphenoidal adenomectomy from 2001 to 2016, 101 patients (16.8%) who had tumors with a high (≥ 3%) Ki-67 index (group A) and a control group consisting of 43 patients with a low (< 3%) Ki 67 index who were matched for age, gender, and tumor type were included. Mitotic index and P53 expressions were evaluated. Patient characteristics, histopathology reports, pre/postoperative magnetic resonance imaging (MRI), and follow-up data were assessed retrospectively. The frequency of macroadenomas and mean tumor size were greater in group A when compared to group B (67.4 vs. 94.1%, p< 0.01 and 25 ± 10.6 vs. 18 ± 11 mm, p< 0.01, respectively). Invasion to cavernous sinus was found in 53 (36.8%) patients and was more frequent in group A (p<0.01). The mean number of surgery was higher in group A than group B (p< 0.05). The mean follow-up period was 46.6 ± 34 months. The postoperative MRIs and follow-up data for at least 24 months were available in 117 patients. Recurrence risk was higher in group A than group B (p = 0.03). Tumors with high Ki-67 proliferation index were grouped as 3-5, 6-10, 11-15, and > 15%. The risk of recurrence was not different between groups of high Ki-67 index. The optimal cutoff point of the Ki-67 proliferation index that predicted recurrence was 2.5% with 84.6% sensitivity and 47.4% specificity. The cavernous sinus invasion on MRI was associated with recurrence (p = 0.03). Tumor size and recurrence risk were not associated with P53 expression. High P53 expression was related with cavernous sinus invasion (p = 0.03). The mitotic index was not associated with recurrence risk and tumor invasion. Recurrence risk was higher in tumors with ≥ 2 histopathological atypia criteria (p = 0.01). High Ki-67 index with a 2.5% cutoff point and cavernous sinus invasion on MRI are reliable markers for predicting recurrence in PAs. Recurrence risk is also higher in tumors with two histopathological aggressiveness criteria. Strict follow-up and more aggressive treatment approaches may be necessary for invasive-proliferative PAs.

Recurrences of Pituitary Adenomas or Second De Novo Tumors: Comparisons with First Tumors

BACKGROUND

Recurrences of pituitary adenomas are not so rare.

METHODS

In the German Registry of Pituitary Tumors, more than 12,000 surgical specimens were collected between 1967 and 2012, of which 312 patients with altogether 334 recurrences (n = 646 specimens) were included in our study.

RESULTS

The histopathology of 162 recurrent adenomas could be compared with the original tumor and 37 second recurrences could be compared with the first recurrence. Comparing the proliferation index (Ki-67) of the original and the first recurrent tumor (n = 162), we found an unchanged index in 43 cases (26%), whereas in 69 cases (43%) the index increased and in 50 cases (31%) it decreased. Comparing the first with the second recurrence (n = 37), we found an unchanged index in 8 cases (22%), an increased index in 15 cases (40%), and a decreased index in 14 cases (38%). The third recurrence showed an unchanged index in 1 case (20%), an increased index in 2 cases (40%), and a decreased index in 2 cases (40%). p53 was unchanged in recurrences in 44% of cases, increased in 33%, and decreased in 22%. In 4 cases, adenomas developed into adenomas with strongly increased proliferation (formerly atypical adenomas, now aggressive adenomas) for the first recurrence, and 9 recurrences became aggressive adenomas. A change of tumor type without change of the common transcription factor occurred in 82 cases.

CONCLUSIONS

A second independent de novo adenoma was present in 10 cases, probably due to changes of transcription factors.

Increased expression of programmed death ligand 1 (PD-L1) in human pituitary tumors

Purpose

Subsets of pituitary tumors exhibit an aggressive clinical courses and recur despite surgery, radiation, and chemotherapy. Because modulation of the immune response through inhibition of T-cell checkpoints has led to durable clinical responses in multiple malignancies, we explored whether pituitary adenomas express immune-related biomarkers that could suggest suitability for immunotherapy. Specifically, programmed death ligand 1 (PD-L1) has emerged as a potential biomarker whose expression may portend more favorable responses to immune checkpoint blockade therapies. We thus investigated the expression of PD-L1 in pituitary adenomas.

Methods

PD-L1 RNA and protein expression were evaluated in 48 pituitary tumors, including functioning and non-functioning adenomas as well as atypical and recurrent tumors. Tumor infiltrating lymphocyte populations were also assessed by immunohistochemistry.

Results

Pituitary tumors express variable levels of PD-L1 transcript and protein. PD-L1 RNA and protein expression were significantly increased in functioning (growth hormone and prolactin-expressing) pituitary adenomas compared to non-functioning (null cell and silent gonadotroph) adenomas. Moreover, primary pituitary adenomas harbored higher levels of PD-L1 mRNA compared to recurrent tumors. Tumor infiltrating lymphocytes were observed in all pituitary tumors and were positively correlated with increased PD-L1 expression, particularly in the functional subtypes.

Conclusions

Human pituitary adenomas harbor PD-L1 across subtypes, with significantly higher expression in functioning adenomas compared to non-functioning adenomas. This expression is accompanied by the presence of tumor infiltrating lymphocytes. These findings suggest the existence of an immune response to pituitary tumors and raise the possibility of considering checkpoint blockade immunotherapy in cases refractory to conventional management.

Ki67 Labeling Correlated With Invasion But Not With Recurrence

Pituitary adenomas account for 10% to 15% of intracranial neoplasms. Multiple factors had been introduced for tumor recurrence. MIB-1 monoclonal antibody, a marker of the proliferative index, has been introduced in various tumors, but unfortunately, the usefulness of MIB-1 in predicting the behavior of pituitary adenoma has been debated recently. Hence, the aim of this study was to evaluate its role in the recurrence and the invasiveness of pituitary adenomas. In a cross-sectional study conducted between 2005 and 2010, patients with a diagnosis of pituitary adenoma, referred to 2 medical centers (Arad and Iran Mehr hospital) in Tehran, were enrolled. Clinical and laboratory data were gathered. Immunostaining for MIB-1 monoclonal antibody was performed for each slide and scored blindly by 2 pathologists. A total of 176 surgically treated patients met the inclusion criteria. Thirty-six of 176 cases had recurrent episodes. Eleven of 176 patients had invasive tumors. The mean Ki67 index was 2.7%±3.96% in recurrent cases and 2.24%±2.35% in nonrecurring cases, with no statistically significant difference between them (P>0.05). Ten of 11 invasive pituitary tumors had a Ki67>3%, and a statistically significant difference was observed between invasive and noninvasive tumors (P<0.05). Hence, the Ki67 index seems to be suitable for predicting invasion, but it failed to show any correlation between Ki67 and tumor recurrence.

Implications of the World Health Organization definition of atypia on surgically treated functional and non-functional pituitary adenomas

BACKGROUND

The World Health Organization (WHO) defines atypical pituitary adenomas as tumours with a MIB-1 labelling index ≥3%, p53 positivity and increased mitotic activity. Although a few reports have described the clinical and radiological correlates of atypia in pituitary adenomas, its impact on postoperative outcomes is not clearly defined.

METHOD

We reviewed preoperative and postoperative records of patients undergoing surgery for pituitary adenomas. Postoperative outcomes for functional adenomas (FPAs) were assessed according to contemporary definitions of remission and recurrence. For non-functional pituitary adenomas (NFPAs), extent of resection and disease progression were defined on the basis of postoperative magnetic resonance imaging.

RESULTS

Of 394 patients included for analysis, 29 cases (7.4%) fulfilled criteria for atypia. Patients with atypical tumours were significantly younger than those with typical adenomas. Remission was possible in 47.4% of FPAs, and was unrelated to the presence of atypia. In NFPAs, local invasiveness was negatively associated with extent of resection (OR, 0.255; 95% CI, 0.086-0.753; p < 0.001). In 93 NFPAs followed postoperatively with serial imaging over a mean duration of 37.5 months, disease progression/recurrence was significantly associated with the presence of atypia (OR, 5.058; 95% CI, 1.273-20.098; p = 0.021) on multivariate analysis.

CONCLUSIONS

Patients with atypical non-functional pituitary adenomas are at risk for postoperative recurrence and disease progression, suggesting a need for adjuvant therapy. However, only a small fraction of pituitary tumours demonstrate atypia, as defined by the WHO, limiting its clinical utility.

Alpha subunit in clinically non-functioning pituitary adenomas: An immunohistochemical study

Pituitary adenomas may be classified as either functioning or non-functioning, depending on whether excess hormone secretion can be clinically identified. Of the six hormones produced in the anterior pituitary, TSH, FSH and LH are known as glycoproteins and contain two subunits (α and β). While α-subunit is identical within all of them, each β-subunit is unique and biologically specific. Independently, the α- and β-subunits are inactive and only induce a hormonal response when they are non-covalently associated. Studies have shown that in certain cases, pituitary adenomas may abnormally secrete only α-subunit, detectable in the serum or through immunohistochemical analysis. In the present study, we examined α-subunit immunoexpression in surgically removed non-functioning pituitary adenomas and analyzed its prognostic value. Results showed that expression of α-subunit in clinically non-functioning pituitary adenomas is not a rare occurrence. While there were no age/gender differences between tumors that expressed α-subunit and those that did not, α-subunit immunonegative adenomas presented with suprasellar extension more frequently and had an Ki67 proliferation greater than 3%. The use of immunohistochemical techniques to determine the presence of α-subunit may provide information on tumor cell proliferation and biologic behavior. To fully understand the role of α-subunit in pituitary adenomas more work is needed.

Clinically non-functioning pituitary adenomas: Pathogenic, diagnostic and therapeutic aspects

Clinically non-functioning pituitary adenomas (NFPAs) are among the most common tumors in the sellar region. These lesions do not cause a hormonal hypersecretion syndrome, and are therefore found incidentally (particularly microadenomas) or diagnosed based on compressive symptoms such as headache and visual field defects, as well as clinical signs of pituitary hormone deficiencies. Immunohistochemically, more than 45% of these adenomas stain for gonadotropins or their subunits and are therefore called gonadotropinomas, while 30% of them show no immunostaining for any hormone and are known as null cell adenomas. The diagnostic approach to NFPAs should include visual field examination, an assessment of the integrity of all anterior pituitary hormone systems, and magnetic resonance imaging of the sellar region to define tumor size and extension. The treatment of choice is transsphenoidal resection of the adenoma, which in many instances cannot be completely accomplished. The recurrence rate after surgery may be up to 30%. Persistent or recurrent adenomas are usually treated with radiation therapy. In a small proportion of these cases, drug treatment with dopamine agonists and, to a lesser extent, somatostatin analogs may achieve reduction or at least stabilization of the tumor.

Current biomarkers of invasive sporadic pituitary adenomas

Though pituitary adenomas (PA) are considered benign, some of them exhibit invasive behaviors such as recurrence and low rate of total surgical resection. Reliable prognostic biomarkers for invasive PA are highly desired; however they remain to be identified. In this review, we summarize the current controversial findings of biomarkers for invasive sporadic PA, and we discuss the possible reasons for the controversies.

Clinical Impact of the Current WHO Classification of Pituitary Adenomas

WHO classifications should be used for comparing the results from different groups of pathologist and clinicians by standardized histopathological methods. Our present report describes the important parameters of pituitary adenoma pathology as demand of the WHO classification for correlation to endocrine data and prognosis. The combination of HE stain based structures with immunostainings for pituitary hormones allows subclassification of adenomas as the best method not only for correlations to clinical hyperfunctions but also for statements to the sensitivity of drug therapies (somatostatin analogs, dopamine agonists). GH-, PRL- and ACTH-secreting pituitary adenomas are further classified based on the size and number of their secretory granules by electron microscopy, or as is mostly the case nowadays by cytokeratin staining pattern, into densely and sparsely granulated. Granulation pattern may be considered for the prediction of treatment response in patients with GH-secreting adenomas, since the sparsely granulated subtype was shown to be less responsive to somatostatin analog treatment. For prognosis, it is important to identify aggressive adenomas by measurements of the Ki-67 index, of the number of mitoses, and of nuclear expression of p53. Among the criteria for atypical adenomas, high Ki-67 labeling index and invasive character are the most important adverse prognostic factors. Promising molecular markers have been identified that might supplement the currently used proliferation parameters. For defining atypical adenomas in a future histopathological classification system, we propose to provide the proliferative potential and the invasive character separately.

Metalloproteinases ADAM12 and MMP-14 are associated with cavernous sinus invasion in pituitary adenomas

Invasion of tumor cells critically depends on cell-cell or cell-extracellular matrix interactions. Enzymes capable of modulating these interactions belong to the proteinase families of ADAM (a disintegrin and metalloprotease) and MMP (matrix metalloprotease) proteins. Our objective is to examine their expression levels and evaluate the relationship between expression levels and cavernous sinus invasion in pituitary adenomas. Tissue samples from 35 patients with pituitary adenomas were analyzed. Quantitative real-time polymerase chain reaction (qPCR) was employed to assess mRNA expression levels for ADAM and MMP genes. Protein levels were examined using immunohistochemistry and Western Blot. Correlation analyses between expression levels and clinical parameters were performed. By silencing ADAM12 and MMP-14 with siRNA in a mouse pituitary adenoma cell line (TtT/GF), their cellular effects were investigated. In our study, nine women and 26 men were included, with a mean age of 53.1 years (range 15-84 years) at the time of surgery. There were 19 cases with cavernous sinus invasion. The proteins ADAM12 and MMP-14 were significantly up-regulated in invasive adenomas compared to noninvasive adenomas. Both human isoforms of ADAM12 (ADAM12L and ADAM12s) were involved in tumor invasion; moreover, ADAM12L was found to correlate positively with Ki-67 proliferation index in pituitary adenomas. In TtT/GF pituitary adenoma cells, silencing of ADAM12 and MMP-14 significantly inhibited cell invasion and migration, respectively, whereas only silencing of ADAM12 suppressed cell proliferation. We conclude that ADAM12 and MMP-14 are associated with cavernous sinus invasion in pituitary adenomas, which qualifies these proteins in diagnosis and therapy.

Multidisciplinary Approach for Acromegaly: A Single Tertiary Center's Experience

BACKGROUND

Acromegaly is a multisystemic disease that requires a multidisciplinary approach. The aim of this study was to determine early and late remissions of patients who underwent surgery at our center and to evaluate relations between pathologic and radiologic properties of adenoma and medical and radiosurgical treatments with remissions.

METHODS

The medical records of 103 patients with acromegaly who underwent endoscopic endonasal transsphenoidal surgery in Cerrahpasa Medical Faculty, Istanbul University, between 2007 and 2014 were reviewed. Clinical, biochemical, radiologic, and pathologic properties were determined.

RESULTS

The total median follow-up time was 38 months [interquartile range: 24-53.5 months]. Thirty-two percent of the adenomas were microadenomas and 68% were macroadenomas The early remission rate was 51.5% and late remission was 75.2%. The sellar floor invasion was significantly lower in patients with early and late remissions (P = 0.01 and P = 0.009, respectively). The initial growth hormone (GH; P < 0.001), first-day GH (P = 0.03), 3-month GH (P = 0.001), insulin-like growth factor-1 (P = 0.004), and 6-month insulin-like growth factor-1 (P = 0.02) levels were significantly greater in patients with sellar floor invasion. The late remission rates (P = 0.004) were greter and reoperation needs (P = 0.05) were lower in patients with Ki-67 <3% than in patients with ≥3%. Seventy (68.6%) patients needed medical therapy during follow-up.

CONCLUSIONS

Late remission was achieved using a multidiciplinary approach in 75.2% of 103 patients with acromegaly, and young age, male sex, high Ki-67 and mitosis indices, and cavernous sinus and sellar-floor invasion had negative effects on clinical and biochemical control of the disease.

Clinicopathological correlates of extrasellar growth patterns in pituitary adenomas

We reviewed clinical, imaging and histopathology details of 297 patients who underwent surgery for pituitary adenomas, with an equal distribution of functional and non-functioning tumors, to examine clinicopathological correlates of extrasellar growth. Knosp grades of 3 and 4 on MRI defined cavernous sinus invasion, Hardy grades of C and D defined significant suprasellar/subfrontal extension, and intraoperative evidence of tumor eroding through the clivus or sellar floor defined infrasellar invasion. Disease status at follow-up was known in 246 patients overall, including 35 patients who were evaluated for progression of residual disease on serial imaging. On univariate analysis, we found several statistically significant associations (p < 0.05) including adenoma size with age, sex and tumor protein p53 reactivity; cavernous sinus invasion with size, non-functional status, increased mitotic activity, an elevated MIB-1 proliferation index and p53 reactivity; suprasellar/subfrontal extension with p53 reactivity; and infrasellar invasion with age and tumor size. When adjusting for confounders with logistic regression, several significant associations were evident including adenoma size with male sex and p53 reactivity; cavernous sinus invasion with size and elevated MIB-1 proliferation index; suprasellar/subfrontal extension with p53 reactivity; and infrasellar invasion with adenoma size alone. Patients with early progression of postoperative residual tumor were younger with a non-significant trend towards higher MIB-1 proliferation indices. Individual patterns of extrasellar growth in pituitary adenomas are associated with unique clinical and immunohistochemical profiles. Younger patients with elevated MIB-1 values are probably at high risk for early recurrence of non-functioning tumors. Definitions of atypia must be standardized before more robust assumptions about tumor biology can be established.

Typical and atypical pituitary adenomas: a single-center analysis of outcome and prognosis

BACKGROUND AND OBJECTIVE

In 2004, the World Health Organization defined atypical pituitary adenomas as those with a Ki-67 expression > 3%, an excessive p53 expression and increased mitotic activity. As the usefulness of this classification is controversial, we reviewed typical and atypical pituitary adenomas to compare the clinical and prognostic features.

PATIENTS AND METHODS

We retrospectively reviewed 343 consecutive pituitary adenomas. Atypical pituitary adenomas represented 18.7% of cases. All patients were operated on at the Department of Neurosurgery of our institution and were followed up at the Hypothalamic-Pituitary Disease Unit of the same institution. The median follow-up time was 75 months (range 7-345).

RESULTS

Younger age at diagnosis as well as immunohistochemical positivity for adrenocorticotropic hormone and prolactin correlated with a higher risk of atypical pituitary adenomas, whereas typical and atypical pituitary adenomas did not differ with regard to gender, tumor size, recurrence risk and disease-free survival time (DFST). Among the 219 patients who underwent radical surgery, a Ki-67 expression ≥ 1.5% was associated with a higher risk of recurrence and a worse DFST, even after correction for age at diagnosis, gender, immunohistochemical classification, tumor size, invasiveness and Knosp classification [p = 0.01; hazard ratio (HR) 2.572; 95% confidence interval (CI) 1.251-5.285). Pituitary adenomas with a Ki-67 expression ≥ 1.5% showed a worse DFST as compared to pituitary adenomas with a Ki-67 expression < 1.5% (HR 2.166; 95% CI 1.154-4.064).

CONCLUSION

In this series, atypical and typical pituitary adenomas did not differ with regard to recurrence and DFST. Pituitary adenomas with a Ki-67 expression ≥ 1.5% showed a higher recurrence risk and a worse DFST as compared to those with a Ki-67 expression < 1.5%. We suggest that a Ki-67 expression ≥ 1.5% may be useful as a prognostic marker, though this will need to be confirmed by prospective, multicenter data.

An analysis of granulation patterns, MIB-1 proliferation indices and p53 expression in 101 patients with acromegaly

BACKGROUND

Despite the wide spectrum of adenoma behavior in patients with acromegaly, the ability of most pathological markers to predict clinical and radiological behavior remains controversial. The authors sought to comprehensively examine clinical and radiological correlates of growth hormone (GH)-secreting pituitary adenomas with regard to several commonly used immunocytochemical techniques in patients undergoing transsphenoidal surgery for acromegaly.

METHOD

We performed a retrospective review of histopathological findings in 101 surgically resected GH adenomas. Tumors were assessed radiologically for different patterns of extension. Each tumor specimen was subject to immunocytochemical analysis, including assessments of granulation patterns, MIB-1 labeling indices, prolactin cosecretion, p53 expression and mitotic activity. Endocrinological outcome was assessed in 93 patients, with remission defined by the 2010 consensus criteria.

RESULTS

Most tumors were macroadenomas and almost half were invasive. When compared to densely granulated tumors, sparsely granulated adenomas were associated with a younger age at presentation, higher preoperative IGF-1 levels, elevated MIB-1 index and pure GH immunostaining, but did not differ significantly in terms of extrasellar invasion or outcome. Increased mitotic activity and p53 expression were also associated with higher proliferation indices and a younger age at presentation. Mixed GH/prolactin tumors demonstrated significantly higher remission rates, independent of variations in extrasellar growth. MIB-1 indices did not correlate with the preoperative GH/IGF-1 levels, adenoma size or Knosp grade.

CONCLUSION

The pathobiology of acromegaly is complex, and the clinicoradiological significance of subtyping on the basis of the markers employed in this study is debatable. Further investigation of newer molecular markers is warranted.

Evaluation of prognostic utility of MIB-1 and p53 expression in pituitary adenomas: correlations with clinical behaviour and follow-up results

Pituitary adenomas (PAs) show a broad clinicomorphological spectrum. The proliferation activity, evaluated by MIB-1 labelling index (LI), and p53 expression have been pointed as predictive markers for invasiveness and progression. The aim of this study was to evaluate the proliferation rate and p53 expression and to look for any relationships with the clinical behaviour and follow-up results in a series of Bulgarian patients with PAs. A total of 93 patients with PAs (81 hormone-secreting, 12 non-functioning), who were operated on and followed up for a period of five years, were included. The MIB-1 LI and p53 expressions were determined by immunohistochemistry and correlated with various clinical and tumour variables. The whole group of PAs showed a low proliferation rate with evident variations in a small number of cases (MIB-1 LI – 0.50 ± 0.56, from 0.1 to 3.30). MIB-1 LI correlated with tumour size (p = 0.012) and was positively related with male gender (p = 0.23) and partial surgical resection (p = 0.036). We found no significant differences regarding the age, functional activity, invasion (n = 33), expansion (n = 37) and tumour recurrences (seven cases). Only 10 cases (10.8%) showed a focal, nuclear p53 immunoreactivity. The p53 positive tumours had higher proliferation rate (p = 0.0001) but no relationship with the other clinical and tumour variables. Among all cases, there was only one case with higher MIB-1 LI (3.3%), positive p53 expression and tumour recurrence after surgery. Our results show that most PAs have a low proliferation rate and lack of p53 expression, as well as no relationship with tumour invasion or postsurgical progression.

The PI3K/AKT/mTOR pathway in the pathophysiology and treatment of pituitary adenomas

Pituitary adenomas are common intracranial neoplasms. Patients with these tumors exhibit a wide range of clinically challenging problems, stemming either from results of sellar mass effect in pituitary macroadenoma or the diverse effects of aberrant hormone production by adenoma cells. While some patients are cured/controlled by surgical resection and/or medical therapy, a proportion of patients exhibit tumors that are refractory to current modalities. New therapeutic approaches are needed for these patients. Activation of the AKT/phophotidylinositide-3-kinase pathway, including mTOR activation, is common in human neoplasia, and a number of therapeutic approaches are being employed to neutralize activation of this pathway in human cancer. This review examines the role of this pathway in pituitary tumors with respect to tumor biology and its potential role as a therapeutic target.

Identification of a subtype-specific ENC1 gene related to invasiveness in human pituitary null cell adenoma and oncocytomas

Non-functioning pituitary adenomas (NFPAs) may be locally invasive. Surgery is a treatment option, but unlike the case for functional pituitary adenomas, there are almost no drug treatments available for NFPAs. Markers of invasiveness are needed to guide therapeutic decision-making and identify potential adjuvant drugs. Owing to the highly heterogeneous nature of NFPAs, little is known regarding the subtype-specific gene expression profiles associated with invasiveness. To identify important biomarkers of invasiveness, we selected 23 null cell adenomas and 20 oncocytomas. These tumors were classified as invasive or non-invasive adenomas based on magnetic resonance imaging, pathology slides and surgical findings. Firstly, we observed that there were significant differences in expression between invasive (n = 3) and non-invasive (n = 4) adenomas by gene expression microarray. A total of 1,188 genes were differentially expressed in the invasive and non-invasive adenomas. Among these 1,188 genes, 578 were upregulated and 610 were downregulated in invasive adenomas. Secondly, the expression of ENC1, which displayed the significant alterations, was further confirmed by qRT-PCR and Western blot analysis in all 43 tumor samples and three normal pituitary glands. Low levels of ENC1 were found in tumor samples, while high levels were detected in normal pituitary glands. Interestingly, the ENC1 expression level was low in invasive null cell adenomas compared with non-invasive adenomas, but this relationship was not observed in invasive oncocytomas. Immunohistochemistry also demonstrated that the staining of ENC1 was different between invasive and non-invasive null cell adenomas. In addition, bioinformatics studies, including gene ontology and protein interaction analyses, were also performed to better understand the critical role of ENC1 in the development and progression of null cell adenomas and oncocytomas. Consequently, ENC1 may be an important biomarker for null cell adenomas and oncocytomas, and it is specific to invasive null cell adenomas.

Radically resected pituitary adenomas: prognostic role of Ki 67 labeling index in a monocentric retrospective series and literature review

Ki-67 Labeling Index is an immunocytochemical marker of cell proliferation. The correlation of Ki-67 expression with pituitary adenomas recurrence has been investigated and is highly debated. Aim of this study was to evaluate whether Ki-67 correlates with recurrence even in patients with an apparently completely removed pituitary adenoma. We retrospectively reviewed the database of the Hypothalamic-Pituitary Disease Unit at the Catholic University of Rome, collected between 2003 and 2011. Inclusion criteria were: patients who underwent surgery at the Department of Neurosurgery with an apparently complete removal of a pituitary adenoma; Ki-67 histological evaluation by the same operator and values of <3%. All patients underwent endocrine evaluation of the hypothalamic-pituitary function, ophthalmologic and neuro-radiological examinations, during the preoperative period and follow-up. Out of 490 patients recorded on the database of the Hypothalamic-Pituitary Disease Unit at the Catholic University of Rome, 191 cases met the inclusion criteria. Recurrence was observed in 49 cases (25.7% of the patients who had undergone radical excision). Optional cut-off value was identified at Ki-67 values of 1.50%. This was associated with worse disease-free survival time, even after correction for age at treatment, gender, positivity to p53, functional classification and Knosp grading. Ki-67 labeling index may be useful in postoperative management, even in patients who underwent radical PA removal. We suggest a Ki-67 cut-off value of 1.5% to plan an adequate clinical follow-up.

The clinical and pathological significance of nitric oxide synthase in human pituitary adenomas: a comparison with MIB-1

The purpose of the present study was to define the clinical and pathological significance of nitric oxide synthase (NOS) in human pituitary adenomas, and to compare these values with those of the MIB-1 labeling index (LI) using an immunohistochemical method. Tissue specimens from 82 cases of surgically-treated pituitary adenomas were immunostained for hormone production for the MIB-1 LI and for the three NOS isoenzymes and five normal pituitary glands were immunostained for the three NOS isoenzymes as a control. The correlation between the clinical variables (age, functional status, tumor size, Hardy's grading, cavernous and/or sphenoid invasiveness, and progression) and mean MIB-1 LI, or between the same clinical variables and NOS immunoreactivity (IR) were analyzed. There was a statistically significant difference in the MIB-1 LI between macroadenomas and microadenomas, and between invasive adenomas and noninvasive adenomas. On the other hand, there was a statistically significant difference in the inducible NOS (iNOS) IR between invasive adenomas and noninvasive adenomas. Furthermore, the iNOS IR had a significant correlation with the MIB-1 LI. Invasive adenomas have a higher iNOS IR, and this correlated with the MIB-1 LI. These findings may be due to the function of iNOS, which plays an important role in tissue injury and repair.

Growth patterns of pituitary adenomas and histopathological correlates

CONTEXT

The factors associated with pituitary adenoma (PA) growth rate remain unclear.

OBJECTIVE

The objective of the study was to establish whether the preoperative growth and extension pattern of PA can predict postoperative growth rate and recurrence in addition to whether the PA growth rate correlates with proliferation and growth factor expression.

PATIENTS

One hundred fifty-three consecutive patients who underwent surgery for pituitary adenoma from 1999 to 2011 at Toronto Western Hospital were identified.

MAIN OUTCOME MEASURES

The PA growth rate was measured both pre- and postoperatively, and its association with patient demographics, magnetic resonance imaging, and histolopathological parameters was determined.

RESULTS

The preoperative growth rate was associated with age (P = .0001), suprasellar growth (P = .003), the presence of a cyst/hemorrhage (P = .004), the mindbomb homolog-1 (P = .005), fibroblast growth factor receptor-4 positivity (P = .047), and p27 negativity (P = .007). After surgery, there were 34.6% residual volumes, which were associated with older age (P = .038) and also with growth patterns including anterior, posterior, suprasellar, and cavernous sinus extension (P = .001); 43.3% of these residuals grew and postoperative growth rate was calculated. Pre- and postoperative growth rates were correlated (r = 0.497, P = .026). Postoperative growth rate was associated with age (P = .015) and gender (P = .017).

CONCLUSIONS

Our data suggest that the growth rate of PAs are influenced by various patient- and tumor-specific characteristics including the age and sex of the patient, the specific subtype of PA, its hormonal activity, its immunohistochemical profile including the mindbomb homolog 1 labeling index status, and its preponderance for different growth directions relative to the pituitary fossa. Furthermore, the pre- and postoperative PA growth rates were correlated, suggesting that postoperative PA growth rates can be predicted, in part, by preoperative growth rates, thus better informing postoperative outcome.

Implications of MGMT methylation status in pituitary adenoma

BACKGROUND

Very little literature exists on frequency of MGMT methylation status in pituitary adenoma. We assessed the frequency of MGMT methylation and protein expression in pituitary adenoma and correlated with patients' age group and prognosis.

METHODS

Tumor tissues from 30 patients with pituitary adenoma were evaluated for MGMT promoter methylation status by methylation specific PCR method. All tumors were also immunostained with MIB-1, anti-p53 and anti-MGMT antibodies.

RESULTS

MGMT methylation status was noted in 40% of cases (7/20 non-functioning adenomas and 5/10 functioning adenomas). MGMT protein expression on IHC was noted in 72.2% of unmethylated tumors, while only 41.6% of methylated tumors demonstrated protein expression. The mean labeling index of MGMT protein was higher in unmethylated tumors as compared to the methylated group, though the difference was not statistically significant (18.6% vs 8.8%; p=0.131). Tumor regrowth occurred in four unmethylated tumors as compared to none in methylated group. Even though there was no correlation between patient age and MGMT methylation status (p=0.823), we noted that the frequency of methylation in middle age patients (between 30 and 59 yrs) was 64.7%, which was higher compared to other age groups.

CONCLUSION

This is the first study from India showing MGMT promoter methylation status with protein expression in pituitary adenoma. We noted that tumor regrowth was higher in unmethylated tumors.

Invasive adenoma and pituitary carcinoma: a SEER database analysis

Invasive pituitary adenomas and pituitary carcinomas are clinically indistinguishable until identification of metastases. Optimal management and survival outcomes for both are not clearly defined. The purpose of this study is to use the Surveillance, Epidemiology, and End Results (SEER) database to report patterns of care and compare survival outcomes in a large series of patients with invasive adenomas or pituitary carcinomas. One hundred seventeen patients diagnosed between 1973 and 2008 with pituitary adenomas/adenocarcinomas were included. Eighty-three invasive adenomas and seven pituitary carcinomas were analyzed for survival outcomes. Analyzed prognostic factors included age, sex, race, histology, tumor extent, and treatment. A significant decrease in survival was observed among carcinomas compared to invasive adenomas at 1, 2, and 5 years (p = 0.047, 0.001, and 0.009). Only non-white race, male gender, and age ≥65 were significant negative prognostic factors for invasive adenomas (p = 0.013, 0.033, and <0.001, respectively). There was no survival advantage to radiation therapy in treating adenomas at 5, 10, 20, or 30 years (p = 0.778, 0.960, 0.236, and 0.971). In conclusion, pituitary carcinoma patients exhibit worse overall survival than invasive adenoma patients. This highlights the need for improved diagnostic methods for the sellar phase to allow for potentially more aggressive treatment approaches.

Clinical neuropathology practice guide 3-2013: levels of evidence and clinical utility of prognostic and predictive candidate brain tumor biomarkers

A large number of potential tissue biomarkers has been proposed for brain tumors. However, hardly any have been adopted for routine clinical use, so far. For most candidate biomarkers substantial controversy exists with regard to their usefulness in clinical practice. The multidisciplinary neurooncology taskforce of the Vienna Comprehensive Cancer Center Central Nervous System Unit (CCC-CNS) addressed this issue and elaborated a four-tiered levels-of-evidence system for assessing analytical performance (reliability of test result) and clinical performance (prognostic or predictive) based on consensually defined criteria. The taskforce also consensually agreed that only biomarker candidates should be considered as ready for clinical use, which meet defined quality standards for both, analytical and clinical performance. Applying this levels-of-evidence system to MGMT, IDH1, 1p19q, Ki67, MYCC, MYCN and β-catenin, only immunohistochemical IDH1 mutation testing in patients with diffuse gliomas is supported by sufficient evidence in order to be unequivocally qualified for clinical use. For the other candidate biomarkers lack of published evidence of sufficiently high analytical test performance and, in some cases, also of clinical performance limits evidence-based confirmation of their clinical utility. For most of the markers, no common standard of laboratory testing exists. We conclude that, at present, there is a strong need for studies that specifically address the analytical performance of candidate brain tumor biomarkers. In addition, standardization of laboratory testing is needed. We aim to regularly challenge and update the present classification in order to systematically clarify the current translational status of candidate brain tumor biomarkers and to identify specific research needs for accelerating the translational pace.

Ki-67 expression for predicting progression of postoperative residual pituitary adenomas: correlations with clinical variables

Reliable prognostic parameters indicating progression in residual pituitary adenoma after surgery are necessary. The World Health Organization classification of tumors of endocrine organs defines atypical pituitary adenomas as tumor with Ki-67 labeling index higher than 3%, excessive p53 immunoreactivity, and increased pleomorphism. The real value of Ki-67 labeling index correlating with tumor progression is controversial. We investigated the relationship between positive labeling for MIB-1 and clinical features of 39 patients with pituitary adenomas with and without rapid re-growth after initial surgery. Ki-67 expression revealed pituitary adenomas with progression (re-growth within 5 years after initial surgery) had a mean proliferation index of 3.66 ± 3.00% (mean ± standard deviation [SD], n = 12), which was significantly higher than in tumors without progression of 1.89 ± 1.25% (mean ± SD, n = 27) (p < 0.05, Mann-Whitney test). Receiver operating characteristic analysis showed a threshold level of Ki-67 expression greater than 2.0% predicts progression with high specificity. Younger patients had higher MIB-1 index and more progression (p < 0.05). Adenomas with cavernous sinus invasion, functioning adenomas, and giant adenomas had higher MIB-1 index (p < 0.05). There was no significant correlation between tumor size or cavernous sinus invasion and progression. More completely removed tumors were less progressive. A threshold of 2% for the MIB-1 labeling index predicts higher risk of progression of residual adenomas after surgery, so shorter interval of follow-up neuroimaging, and early initiation of adjuvant therapy might be required.

Predicting outcomes of patients with intracranial meningiomas using molecular markers of hypoxia, vascularity, and proliferation

BACKGROUND

The natural history of surgically treated intracranial meningiomas can be quite variable. Recurrence and patient outcome cannot currently be predicted with accuracy.

OBJECTIVE

To explore the potential roles of tumor hypoxia-regulated biological markers, preoperative imaging, measures of proliferation, and angiogenesis in predicting patient outcome.

METHODS

Tissue from 263 patients (average follow-up, 75 months) was examined for molecular markers hypoxia-inducible factor-1α (HIF-1α), carbonic anhydrase-IX (CA-IX), and glucose transporter-1 (Glut-1); vascular endothelial growth factor (VEGF); proliferation (MIB-1); and microvascular density (MVD) (Factor VIII). Preoperative magnetic resonance images were also examined for tumor size and peritumoral brain edema (PTBE).

RESULTS

VEGF, HIF-1α, CA-IX, and Glut-1 are positively correlated (P < .001-.005). PTBE was associated with higher grade (P = .03), larger tumors (P = .02), and log of MVD (P = .004). Progression-free survival (PFS) was associated with higher grade (P < .001), subtotal resection (P = .004), VEGF expression (P = .004), and log of MIB-labeling index (P < .001) on pairwise comparisons. Using multivariate analysis, PFS was associated with subtotal resection (HR 2.71, P = .027), higher grade (HR 6.29, P < .001), higher VEGF expression (HR 1.52, P = .038), and log of MIB-labeling index (HR 1.68, P = .005). Shorter overall survival was associated with subtotal resection (HR 3.23, P = .002), higher grade (HR 4.47, P < .001), higher expression of HIF-1α (HR 1.56, P < .001) and Glut-1 (HR 1.39, P = .02), and log of MIB-labeling index (HR 1.87, P < .001) when controlled for age.

CONCLUSION

HIF, VEGF, and MIB-1 are significantly correlated with tumor recurrence. With further study, these molecular markers may be used to predict outcome for patients with intracranial meningiomas.

Correlation between histological subtypes and MRI findings in clinically nonfunctioning pituitary adenomas

Clinically nonfunctioning pituitary adenomas (CNFPAs) consist of several histological subtypes, including null cell adenoma (NCA), silent gonadotroph cell adenoma (SGA), silent corticotroph adenoma (SCA), and other silent adenomas (OSA) (i.e., GH, TSH, and prolactin adenomas). To detect possible correlations between MRI findings and the subtypes, we retrospectively studied 390 consecutive patients with CNFPA who underwent surgery between 2008 and 2010. They were classified into three groups: NCA/SGA (313 cases), SCA (39 cases), and OSA (36 cases); in addition there were two unusual cases of plurihormonal adenoma. Three MRI findings were less common in NCA/SGA than in the other groups (P < 0.0001): giant adenoma (>40 mm), marked cavernous sinus invasion (Knosp grade 4), and lobulated configuration of the suprasellar tumor. When these MRI findings were negative in patients older than 40 years old, 91.0% (212/233) were NCA/SGA. These MRI findings were frequently noted despite a low MIB-1 index in SCA. OSA showed a high MIB-1 index and a preponderance in younger patients. In conclusion, although SCA and OSA consisted of only 20% of CNFPAs, their frequency significantly increased when the tumor was large, invasive, and lobulated, and the patient was younger than 40 years old.