The epidemiology of aggressive pituitary tumors (and its challenges)

The biological behavior and clinical outcome of pituitary adenoma are affected by the microenvironment

BACKGROUND

Pituitary adenoma is one of the most common brain tumors. Most pituitary adenomas are benign and can be cured by surgery and/or medication. However, some pituitary adenomas show aggressive growth with a fast growth rate and are resistant to conventional treatments such as surgery, drug therapy, and radiation therapy. These tumors, referred to as refractory pituitary adenomas, often relapse or regrow in the early postoperative period. The tumor microenvironment (TME) has recently been identified as an important factor affecting the biological manifestations of tumors and acts as the main battlefield between the tumor and the host immune system.

MAIN BODY

In this review, we focus on describing TME in pituitary adenomas and refractory pituitary adenomas. Research on the immune microenvironment of pituitary adenomas is currently focused on immune cells such as macrophages and lymphocytes, and extensive research and experimental verifications are still required regarding other components of the TME. In particular, studies are needed to determine the role of the TME in the specific biological behaviors of refractory pituitary adenomas, such as high invasion, fast recurrence rate, and high tolerance to traditional treatments and to identify the mechanisms involved.

CONCLUSION

Overall, we summarize the similarities and differences between the TME of pituitary adenomas and refractory pituitary adenomas as well as the changes in the biological behavior of pituitary adenomas that may be caused by the microenvironment. These changes greatly affect the outcome of patients.

Transcriptome Analysis Reveals Distinct Patterns Between the Invasive and Noninvasive Pituitary Neuroendocrine Tumors

Although most pituitary neuroendocrine tumors (PitNETs)/pituitary adenomas remain intrasellar, a significant proportion of tumors show parasellar invasive growth and 6% to 8% infiltrate the bone structures, thus affecting the prognosis. There is an unmet need to identify novel markers that can predict the parasellar growth of PitNETs. Furthermore, mechanisms that regulate bone invasiveness of PitNETs and factors related to tumor vascularization are largely unknown. We used genome-wide mRNA analysis in a cohort of 77 patients with PitNETs of different types to explore the differences in gene expression patterns between invasive and noninvasive tumors with respect to the parasellar growth and regarding the rare phenomenon of bone invasiveness. Additionally, we studied the genes correlated to the contrast enhancement quotient, a novel radiological parameter of tumor vascularization. Most of the genes differentially expressed related to the parasellar growth were genes involved in tumor invasiveness. Differentially expressed genes associated with bone invasiveness are involved in NF-κB pathway and antitumoral immune response. Lack of clear clustering regarding the parasellar and bone invasiveness may be explained by the influence of the cell lineage-related genes in this heterogeneous cohort of PitNETs. Our transcriptomics analysis revealed differences in the molecular fingerprints between invasive, including bone invasive, and noninvasive PitNETs, although without clear clustering. The contrast enhancement quotient emerged as a radiological parameter of tumor vascularization, correlating with several angiogenesis-related genes. Several of the top genes related to the PitNET invasiveness and vascularization have potential prognostic and therapeutic application requiring further research.

[Aggressive pituitary tumors and carcinomas: modern classification, advances and prospects in treatment]

Despite slow growth of most pituitary tumors and high rates of total resection and/or effective therapy, pituitary neoplasms are characterized by aggressive behavior with high growth rate, frequent relapses and resistance to standard treatments in 10% of cases. In modern WHO classifications of tumors of the central nervous system, endocrine and neuroendocrine tumors, the authors propose the definition «pituitary neuroendocrine tumor» instead of previous «pituitary adenoma» and «metastasizing pituitary neuroendocrine tumor» instead of «pituitary carcinoma». Currently, there are no effective prognostic markers of aggressive tumors. This complicates early diagnosis. It is proposed to apply a five-stage prognostic classification based on proliferation rate (including mitotic count, Ki-67 index and p53 immunoexpression) and morphometric markers of invasiveness for all resected pituitary neoplasms. This approach would be valuable for earlier detection of aggressive tumors and pituitary carcinomas. Compression of visual pathways, third ventricle and brain stem due to rapid growth of aggressive tumors usually requires redo surgeries with subsequent radiotherapy. Hormonally active tumors require therapy with somatostatin analogues and dopamine agonists in maximum possible doses. Chemotherapy with temozolomide as first-line option is recommended if standard treatment is ineffective. Alternative treatment includes peptide receptor radionuclide therapy (PRRT), molecular targeted therapy (bevacizumab, tyrosine kinase inhibitors, everolimus and cyclin-dependent kinase inhibitors) and immunotherapy (checkpoint inhibitors). Considering the need for combined treatment, these cases should always be discussed by a multidisciplinary team (neurosurgeon, endocrinologist, radiotherapist, oncologist, pathologist) with necessary qualifications and experience in treating these patients. Treatment of aggressive tumors and pituitary carcinomas is becoming an active and rapidly developing direction in neurosurgery, endocrinology and oncology.

Aggressive and Metastatic Pituitary Neuroendocrine Tumors: Therapeutic Management and Off-Label Drug Use

Pituitary neuroendocrine tumors (PitNETs) are the most common pituitary tumors and the second most common brain tumors. Although the vast majority (>90%) are benign, a small percentage (<2%) are aggressive. These aggressive PitNETs (AgPitNETs) are defined by the presence of radiological invasion, a high rate of cell proliferation, resistance to conventional treatments, and/or a high propensity for recurrence. Lastly, there are the rare pituitary carcinomas, also known as metastatic PitNETs (MetPitNETs), which account for only 0.2% of cases and are defined by the presence of craniospinal or distant metastases. At present, there are no definitive factors that allow us to predict with certainty the aggressive behavior of PitNETs, making the therapeutic management of AgPitNETs a real challenge. Surgery is considered the first-line treatment for AgPitNETs and MetPitNETs. Radiation therapy can be effective in controlling tumor growth and regulating hormone hypersecretion. Currently, there are no approved non-endocrine medical therapies for the management of AgPitNETs/MetPitNETs, mainly due to the lack of randomized controlled clinical trials. As a result, many of the medical therapies used are off-label drugs, and several are under investigation. Temozolomide (TMZ) is now recognized as the primary medical treatment following the failure of standard therapy (medical treatment, surgery, and radiotherapy) in AgPitNETs/MetPitNETs due to its ability to improve overall and progression-free survival rates in responding patients over 5 years. Other therapeutic options include pituitary-targeted therapies (dopamine agonists and somatostatin analogs), hormonal antisecretory drugs, non-hormonal targeted therapies, radionuclide treatments, and immunotherapy. However, the number of patients who have undergone these treatments is limited, and the results obtained to date have been inconsistent. As a result, it is imperative to expand the cohort of patients undergoing treatment to better determine the therapeutic efficacy and safety of these drugs for individuals with AgPitNETs/MetPitNETs.

Pituitary adenoma or neuroendocrine tumour: the need for an integrated prognostic classification

In the 2022 fifth edition of the WHO Classification of Endocrine Tumours and of Central Nervous System Tumours, pituitary adenomas are reclassified as neuroendocrine tumours (NETs). This change confers an oncology label to neoplasms that are overwhelmingly benign. A comprehensive clinical classification schema is required to guide prognosis, therapy and outcomes for all patients with pituitary adenomas. Pituitary adenomas and NETs exhibit some morphological and ultrastructural similarities. However, unlike NETs, pituitary adenomas are highly prevalent, yet indolent and rarely become malignant. This Perspective presents the outcomes of an interdisciplinary international workshop that addressed the merit and clinical implications of the classification change of pituitary adenoma to NET. Many non-histological factors provide mechanistic insight and influence the prognosis and treatment of pituitary adenoma. We recommend the development of a comprehensive classification that integrates clinical, genetic, biochemical, radiological, pathological and molecular information for all anterior pituitary neoplasms.

A pan-tissue survey of mosaic chromosomal alterations in 948 individuals

Genetic mutations accumulate in an organism's body throughout its lifetime. While somatic single-nucleotide variants have been well characterized in the human body, the patterns and consequences of large chromosomal alterations in normal tissues remain largely unknown. Here, we present a pan-tissue survey of mosaic chromosomal alterations (mCAs) in 948 healthy individuals from the Genotype-Tissue Expression project, augmenting RNA-based allelic imbalance estimation with haplotype phasing. We found that approximately a quarter of the individuals carry a clonally-expanded mCA in at least one tissue, with incidence strongly correlated with age. The prevalence and genome-wide patterns of mCAs vary considerably across tissue types, suggesting tissue-specific mutagenic exposure and selection pressures. The mCA landscapes in normal adrenal and pituitary glands resemble those in tumors arising from these tissues, whereas the same is not true for the esophagus and skin. Together, our findings show a widespread age-dependent emergence of mCAs across normal human tissues with intricate connections to tumorigenesis.

Analysis of risk factors of pituitary neoplasms invading the sphenoidal sinus

High-resolution computed tomography (HR-CT) can more effectively discern the relationship between pituitary neoplasms (PNs) and neighboring anatomical structures. Moreover, pathological features can facilitate a more accurate determination of the growth pattern of PNs. Consequently, integrating imaging and pathological data might enhance our predictive capability regarding the growth patterns of PNs and aid in the formulation of surgical plans. We compared HR-CT images of 54 patients and 52 volunteers. Using ITK-SNAP software, we segmented and reconstructed the anatomical features of the sphenoidal sinus (SS) and calculated its volume. A comparative analysis of the invasive attributes of the 54 PNs was carried out based on clinical features and pathological data. The average volume of the SS in the volunteer group was 11.05 (8.10) mL, significantly larger than that of the PNs group at 7.45 (4.88) mL (P = .005). The postsellar type was the most common pneumatization type, and a significantly higher proportion in the PNs group exhibited a depressed saddle base (83.3%). A notable male predominance was observed for SS invasion in the PNs group (72.7%), with the Ki-67 antigen and maximum diameter significantly higher (P < .05), showing a positive correlation. The optimal cutoff points for Ki-67 antigen and the maximum diameter of PNs were 3.25% (AUC = 0.754, Sensitivity 54.5%, Specificity 90.6%) and 24.5 mm (AUC = 0.854, Sensitivity 86.4%, Specificity 78.1%), respectively. The type of pneumatization and the morphology of the sellar-floor serve as anatomical foundations for SS invasion. Factors such as the Ki-67 antigen, the maximum diameter of PNs, and high-risk sub-types constitute risk factors for PNs invasion into the SS. These insights are of significant utility for clinicians in crafting treatment strategies for PNs.

Molecular Imaging of Pituitary Tumors

Tumors of the pituitary gland, although mostly benign adenomas, are a cause of significant morbidity and even excess mortality due to local compressive effects (eg visual loss, hypopituitarism) and unregulated hormone secretion (eg acromegaly or Cushing Disease). Surgery, radiotherapy, and medical management (sometimes in combination) may be needed to mitigate the effects of tumor expansion and endocrine dysfunction. Magnetic resonance imaging (MRI) plays a central role in treatment planning for most patients. However, it does not always reliably identify the site(s) of primary or recurrent disease, especially where post-treatment remodeling results in indeterminate anatomical appearances. In these contexts, molecular imaging is a potential game-changer, allowing precise localization of sites of active disease and enabling safe and effective targeted intervention when patients would otherwise be consigned to expensive life-long medication. For pituitary and parasellar imaging, PET is the preferred modality due to its superior spatial resolution and sensitivity compared with SPECT, and an array of PET radioligands have been studied in different pituitary adenoma (PA) subtypes. While 18F-fluorodeoxyglucose (18F-FDG) is widely available, significant heterogeneity in tumoral uptake has limited its use. Instead, ligands targeting specific molecular pathways relevant to PA biology (eg somatostatin or dopamine receptor expression, amino acid uptake) are increasingly preferred and are beginning to find application in routine clinical practice. In addition, novel approaches to distinguish adenomatous tissue from normal gland (eg through comparison of images obtained with different radiotracers) and increase confidence that a suspected abnormal focus is indeed pathological (eg through subtraction imaging) have been proposed. It is likely therefore that molecular imaging will continue to find increasing application in the management of pituitary tumors just as it already does in other endocrine disorders.

The Role of Activation of PI3K/AKT/mTOR and RAF/MEK/ERK Pathways in Aggressive Pituitary Adenomas-New Potential Therapeutic Approach-A Systematic Review

Pituitary tumors (PT) are mostly benign, although occasionally they demonstrate aggressive behavior, invasion of surrounding tissues, rapid growth, resistance to conventional treatments, and multiple recurrences. The pathogenesis of PT is still not fully understood, and the factors responsible for its invasiveness, aggressiveness, and potential for metastasis are unknown. RAF/MEK/ERK and mTOR signaling are significant pathways in the regulation of cell growth, proliferation, and survival, its importance in tumorigenesis has been highlighted. The aim of our review is to determine the role of the activation of PI3K/AKT/mTOR and RAF/MEK/ERK pathways in the pathogenesis of pituitary tumors. Additionally, we evaluate their potential in a new therapeutic approach to provide alternative therapies and improved outcomes for patients with aggressive pituitary tumors that do not respond to standard treatment. We perform a systematic literature search using the PubMed, Embase, and Scopus databases (search date was 2012-2023). Out of the 529 screened studies, 13 met the inclusion criteria, 7 related to the PI3K/AKT/mTOR pathway, and 7 to the RAF/MEK/ERK pathway (one study was used in both analyses). Understanding the specific factors involved in PT tumorigenesis provides opportunities for targeted therapies. We also review the possible new targeted therapies and the use of mTOR inhibitors and TKI in PT management. Although the RAF/MEK/ERK and PI3K/AKT/mTOR pathways play a pivotal role in the complex signaling network along with many interactions, further research is urgently needed to clarify the exact functions and the underlying mechanisms of these signaling pathways in the pathogenesis of pituitary adenomas and their role in its invasiveness and aggressive clinical outcome.

Aggressive Pituitary Tumors and Pituitary Carcinomas: From Pathology to Treatment

Aggressive pituitary tumors (APTs) and pituitary carcinomas (PCs) are heterogeneous with regard to clinical presentation, proliferative markers, clinical course, and response to therapy. Half of them show an aggressive course only many years after the first apparently benign presentation. APTs and PCs share several properties, but a Ki67 index greater than or equal to 10% and extensive p53 expression are more prevalent in PCs. Mutations in TP53 and ATRX are the most common genetic alterations; their detection might be of value for early identification of aggressiveness. Treatment requires a multimodal approach including surgery, radiotherapy, and drugs. Temozolomide is the recommended first-line chemotherapy, with response rates of about 40%. Immune checkpoint inhibitors have emerged as second-line treatment in PCs, with currently no evidence for a superior effect of dual therapy compared to monotherapy with PD-1 blockers. Bevacizumab has resulted in partial response (PR) in few patients; tyrosine kinase inhibitors and everolimus have generally not been useful. The effect of peptide receptor radionuclide therapy is limited as well. Management of APT/PC is challenging and should be discussed within an expert team with consideration of clinical and pathological findings, age, and general condition of the patient. Considering that APT/PCs are rare, new therapies should preferably be evaluated in shared standardized protocols. Prognostic and predictive markers to guide treatment decisions are needed and are the scope of ongoing research.

Refractory nonfunctioning pituitary adenomas

Non-functioning pituitary adenomas (NFPAs) comprise silent tumors of different pituitary lineages that tend to escape early detection and present as invasive macroadenomas with symptoms of mass effect. Incomplete surgical resection is common and may be followed by significant rates of subsequent remnant progression. Pituitary tumors are defined as refractory when resistance to optimal standard therapies including surgery, radiotherapy, and medical treatment is documented. In the absence of approved medications for the treatment of NFPAs, the last criterion to classify these tumors as refractory is ill defined. Silent corticotroph and null cell adenomas have been reported, albeit not in all studies, to be larger and recur more often compared with silent gonadotroph tumors. Nevertheless, it is currently unknown if certain NFPA subtypes are more often refractory using well defined criteria. The response rate to temozolomide is lower in NFPA compared to that seen in functioning tumors. Refractory NFPAs present a significant diagnostic and therapeutic challenge and are associated with increased morbidity and mortality rates.

Non-functioning pituitary carcinoma: Case report and literature review

INTRODUCTION AND IMPORTANCE

Non-functional pituitary carcinoma is a rare neuroendocrine tumor. It is characterized by the presence of cerebrospinal or distant metastasis of an adenohypophysis tumor without any hypersecretion. Only a few cases of non-functional pituitary carcinomas have been reported in the literature.

CASE PRESENTATION

In this paper, we report the case of a 48-year-old female patient who presented with spinal pain and a mass facing the second thoracic vertebrae. Spinal magnetic resonance imaging (MRI) revealed the presence of pituitary and bilateral adrenal incidentalomas. The patient was operated and the histopathological examination of the specimen revealed a non-functional pituitary carcinoma variety "Null Cell".

DISCUSSION AND CONCLUSION

There are no clinical, biological, or radiological characteristics that reliably differentiate between non-functional pituitary adenoma and non-functional pituitary carcinoma. Management remains a challenge for clinicians and neurosurgeons. A combination of surgery, chemotherapy, and radiotherapy seems necessary to achieve tumor control.

The Effects of Peptide Receptor Radionuclide Therapy on the Neoplastic and Normal Pituitary

Pituitary neuroendocrine tumours (PitNETs) are usually benign and slow-growing; however, in some cases, they may behave aggressively and become resistant to conventional treatments. Therapeutic options for aggressive or metastatic PitNETs are limited, and currently mainly consist of temozolomide, with little experience of other emerging approaches, including peptide receptor radionuclide therapy (PRRT). Somatostatin receptor expression in PitNETs explains the effectiveness of somatostatin analogues for treating PitNETs, particularly those hypersecreting pituitary hormones, such as growth hormone or adrenocorticotropic hormone. The expression of such receptors in pituitary tumour cells has provided the rationale for using PRRT to treat patients with aggressive or metastatic PitNETs. However, the PRRT efficacy in this setting remains unestablished, as knowledge on this today is based only on few case reports and small series of cases, which are reviewed here. A total of 30 PRRT-treated patients have been thus far reported: 23 aggressive PitNETs, 5 carcinomas, and 2 of malignancy status unspecified. Of the 27 published cases with information regarding the response to PRRT, 5 (18%) showed a partial response, 8 (30%) had stable disease, and 14 (52%) had progressive disease. No major adverse effects have been reported, and there is also no increased risk of clinically relevant hypopituitarism in patients with pituitary or non-pituitary neuroendocrine tumours following PRRT. PRRT may be regarded as a safe option for patients with aggressive or metastatic PitNETs if other treatment approaches are not feasible or have failed in controlling the disease progression, with tumour shrinkage occurring in up to a fifth of cases, while about a third of aggressive pituitary tumours may achieve stable disease. Here, the data on PRRT in the management of patients with aggressive pituitary tumours are reviewed, as well as the effects of PRRT on the pituitary function in other PRRT-treated cancer patients.

Recent Therapeutic Advances in Pituitary Carcinoma

Pituitary carcinoma (PC) is a rare, aggressive malignancy that comprises 0.1-0.2% of all pituitary tumors. PC is defined anatomically as a pituitary tumor that metastasizes outside the primary intrasellar location as noncontiguous lesions in the central nervous system or as metastases to other organs. Similar to pituitary adenoma, PC originates from various cell types of the pituitary gland and can be functioning or nonfunctioning, with the former constituting the majority of the cases. Compression of intricate skull-based structures, excessive hormonal secretion, impaired pituitary function from therapy, and systemic metastases lead to debilitating symptoms and a poor survival outcome in most cases. PC frequently recurs despite multimodality treatments, including surgical resection, radiotherapy, and biochemical and cytotoxic treatments. There is an unmet need to better understand the pathogenesis and molecular characterization of PC to improve therapeutic strategies. As our understanding of the role of signaling pathways in the tumorigenesis of and malignant transformation of PC evolves, efforts have focused on targeted therapy. In addition, recent advances in the use of immune checkpoint inhibitors to treat various solid cancers have led to an interest in exploring the role of immunotherapy for the treatment of aggressive refractory pituitary tumors. Here, we review our current understanding of the pathogenesis, molecular characterization, and treatment of PC. Particular attention is given to emerging treatment options, including targeted therapy, immunotherapy, and peptide receptor radionuclide therapy.

Pituitary Tumorigenesis-Implications for Management

Pituitary neuroendocrine tumors (PitNETs), the third most common intracranial tumor, are mostly benign. However, some of them may display a more aggressive behavior, invading into the surrounding structures. While they may rarely metastasize, they may resist different treatment modalities. Several major advances in molecular biology in the past few years led to the discovery of the possible mechanisms involved in pituitary tumorigenesis with a possible therapeutic implication. The mutations in the different proteins involved in the Gsa/protein kinase A/c AMP signaling pathway are well-known and are responsible for many PitNETS, such as somatotropinomas and, in the context of syndromes, as the McCune-Albright syndrome, Carney complex, familiar isolated pituitary adenoma (FIPA), and X-linked acrogigantism (XLAG). The other pathways involved are the MAPK/ERK, PI3K/Akt, Wnt, and the most recently studied HIPPO pathways. Moreover, the mutations in several other tumor suppressor genes, such as menin and CDKN1B, are responsible for the MEN1 and MEN4 syndromes and succinate dehydrogenase (SDHx) in the context of the 3PAs syndrome. Furthermore, the pituitary stem cells and miRNAs hold an essential role in pituitary tumorigenesis and may represent new molecular targets for their diagnosis and treatment. This review aims to summarize the different cell signaling pathways and genes involved in pituitary tumorigenesis in an attempt to clarify their implications for diagnosis and management.

Initial pathology in aggressive pituitary tumours and carcinomas: 2b or not 2b?-that is the question

From a cohort of 171 patients comprising 121 aggressive pituitary tumours (APT) and 50 pituitary carcinomas (PC), the clinicopathological or five-tiered classification based on tumour invasion and proliferation evaluated by at least 2 proliferative markers over the cut-offs (Ki-67 ≥3% or ≥10%, p53 positive or expressed in %, mitotic count &gt;2%), could be applied on 43 tumours: 20 PC and 23 APT. At the initial surgery, 29/43 tumours (67.4%) were grade 2b (invasive and proliferative) of which 44.8% developed metastases during follow-up (PC, grade 3). Out of these 29 tumours, 55.1% had a Ki-67 ≥10%, and were classified grade 2b* (invasive and highly proliferative). There was one tumour grade 1b* (non-invasive and highly proliferative) which metastazed. Out of the 43 tumours, 30.2 % were grade 2a (invasive and non-proliferative). The sensitivity and the specificity of grade 2b for the diagnosis of APT at the initial surgery, were 68% and 90% respectively. The comparison of the high percentage (67.4%) of grade 2b tumours in this selected cohort of APT/PC with the low percentage (8.8%) in a surgical cohort of unselected tumours shows that the initial pathological diagnosis of grade 2b tumour may be considered, in the clinic, as representing a diagnosis of APT. In addition, a significant subgroup of tumours, which will develop metastases supports the proposal that an aggressive grade 2b tumour is “a tumour with malignant potential” or “a malignant tumour without metastases”. So, the clinician may take into account the pathological diagnosis, at the initial surgery, to propose a strict follow-up and to consider earlier use of radiotherapy and/or of temozolomide in the presence of tumours with aggressive behaviour.

Aggressive pituitary tumors (PitNETs)

The majority of anterior pituitary tumors behave benignly, that is, they grow slowly and do not metastasize, and were therefore called adenomas. However, they would frequently invade adjacent structures, leading to recurrence. One of the misleading assumptions in their previous classification was the simplistic distinction made between adenoma and carcinoma. In the upcoming WHO 2022 classification, a new terminology will be introduced: pituitary neuroendocrine tumor (PitNET) which is consistent with that used for other neuroendocrine neoplasms. In general, aggressive PitNETs are invasive and proliferative tumors with frequent recurrences, resistant to conventional treatments, and yet virtually without metastases. At present, no single morphological or histological marker has been shown as yet to reliably predict their aggressive behavior. In terms of treatment, temozolomide (TMZ) had been considered promising and the sole therapeutic option for aggressive and malignant PitNETs following failure of standard therapies. However, recent reports have disclosed that TMZ does not provide long-term control of many aggressive PitNETs. A further multidisciplinary approach is necessary for both reliable prediction and successful management of aggressive PitNETs.

Shape and texture analyses based on conventional MRI for the preoperative prediction of the aggressiveness of pituitary adenomas

OBJECTIVES

Pituitary adenomas can exhibit aggressive behavior, characterized by rapid growth, resistance to conventional treatment, and early recurrence. This study aims to evaluate the clinical value of shape-related features combined with textural features based on conventional MRI in evaluating the aggressiveness of pituitary adenomas and develop the best diagnostic model.

METHODS

Two hundred forty-six pituitary adenoma patients (84 aggressive, 162 non-aggressive) who underwent preoperative MRI were retrospectively reviewed. The patients were divided into training (n = 193) and testing (n = 53) sets. Clinical information, shape-related, and textural features extracted from the tumor volume on contrast-enhanced T1-weighted images (CE-T1WI), were compared between aggressive and non-aggressive groups. Variables with significant differences were enrolled into Pearson's correlation analysis to weaken multicollinearity. Logistic regression models based on the selected features were constructed to predict tumor aggressiveness under fivefold cross-validation.

RESULTS

Sixty-five imaging features, including five shape-related and sixty textural features, were extracted from volumetric CE-T1WI. Forty-seven features were significantly different between aggressive and non-aggressive groups (all p values < 0.05). After feature selection, four features (SHAPE_Sphericity, SHAPE_Compacity, DISCRETIZED_Q3, and DISCRETIZED_Kurtosis) were put into logistic regression analysis. Based on the combination of these features and Knosp grade, the model yielded an area under the curve value of 0.935, with a sensitivity of 94.4% and a specificity of 82.9%, to discriminate between aggressive and non-aggressive pituitary adenomas in the testing set.

CONCLUSION

The radiomic model based on tumor shape and textural features study from CE-T1WI might potentially assist in the preoperative aggressiveness diagnosis of pituitary adenomas.

KEY POINTS

• Pituitary adenomas with aggressive behavior exhibit rapid growth, resistance to conventional treatment, and early recurrence despite gross resection and may require multiline treatments. • Shape-related features and texture features based on CE-T1WI were significantly correlated with the Ki-67 labeling index, mitotic count, and p53 expression, and the proposed model achieved a favorable prediction of the aggressiveness of PAs with an AUC value of 0.935. • The prediction model might provide valuable guidance for individualized treatment in patients with PAs.

Updates in neuroendocrine neoplasms: From mechanisms to the clinic

Scientific advances constantly improve our understanding of the mechanisms underlying tumorigenesis, allowing us now to analyze cancer in a more precise manner and to identify at an earlier stage the tumors that have greater risk of aggressive behavior. Understanding neuroendocrine neoplasms at molecular level has enabled increasingly targeted treatments, with safety and efficacy validated in large randomized trials. Moreover, the first studies of targeted therapies after molecular profiling of neuroendocrine neoplasms have shown encouraging results, allowing us to foresee ever more personalized medical treatments in the future. This literature review aims to summarize recent advances in the study of neuroendocrine neoplasms and to show how identification of new mechanisms underlying tumorigenesis can be of benefit in clinical practice.

Natural history of pituitary carcinoma with metastasis to the cervical spine: illustrative case

BACKGROUND

Pituitary carcinoma is a rare tumor of the adenohypophysis with noncontiguous craniospinal dissemination and/or systemic metastases. Given the rarity of this malignancy, there is limited knowledge and consensus regarding its natural history, prognosis, and optimal treatment.

OBSERVATIONS

The authors present the case of a 46-year-old woman initially treated with invasive prolactin-secreting pituitary macroadenoma who developed metastatic disease of the cervical spine 6 years later. The patient presented with acutely worsening compressive cervical myelopathy and required posterior cervical decompression, tumor resection, and instrumented arthrodesis for posterolateral fusion.

LESSONS

This case underscores the importance of long-term monitoring of hormone levels and having a high clinical suspicion for metastatic disease to the spine in patients presenting with acute myelopathy or radiculopathy in the setting of previously treated invasive secreting pituitary adenoma.

Closure strategy for endoscopic pituitary surgery: Experience from 3015 patients

Introduction

Effective strategies are required to ensure optimal management of the crucial closure step in endoscopic pituitary surgery. Many surgical techniques have been reported but no significant consensus has been defined.

Methods

Between January 2006 and March 2022, 3015 adult patients with pituitary adenomas were operated on by a single expert neurosurgical team, using a mononostril endoscopic endonasal approach. Based of preoperative risk factors of and operative findings, a detailed closure strategy was used. Body mass index >40, sellar floor lysis, number of surgeries>2, large skull base destruction, prior radiotherapy were considered as preoperative risk factors for closure failure. All patients treated with an expanded endonasal approach were excluded.

Results

Patients were mostly women (F/M ratio: 1.4) with a median age of 50 (range: 18 -89). Intraoperative CSF leak requiring specific surgical management was observed in 319/3015 (10.6%) of patients. If intraoperative leak occurred, patients with predictive risk factors were managed using a Foley balloon catheter in case of sellar floor lysis or BMI>40 and a multilayer repair strategy with a vascularized nasoseptal flap in other cases. Postoperative CSF leak occurred in 29/3015 (1%) of patients, while meningitis occurred in 24/3015 (0.8%) of patients. In patients with intraoperative leak, closure management failed in 11/319 (3.4%) of cases.

Conclusion

Based on our significant 16-year experience, our surgical management is reliable and easy to follow. With a planned and stepwise strategy, the closure step can be optimized and tailored to each patient with a very low failure rate.

Multidisciplinary management of difficult/aggressive growth-hormone pituitary neuro-endocrine tumors

Growth Hormone-secreting adenomas exhibits variable biological behavior and heterogeneous natural history, ranging from small adenomas and mild disease, to invasive and aggressive neoplasms with more severe clinical picture. Patients not cured or controlled after neurosurgical and first-generation somatostatin receptor ligands (SRL) therapy could require multiple surgical, medical and/or radiation treatments to achieve disease control. To date, no clinical, laboratory, histopathological, or neuroradiological markers are able to define the aggressiveness or predict the disease prognosis in patients with acromegaly. Therefore, the management of these patients requires careful evaluation of laboratory assessments, diagnostic criteria, neuroradiology examinations, and neurosurgical approaches to choose an effective and patient-tailored medical therapy. A multidisciplinary approach is particularly useful in difficult/aggressive acromegaly to schedule multimodal treatment, which includes radiation therapy, chemotherapy with temozolomide and other, recent emerging treatments. Herein, we describe the role of the different members of the multidisciplinary team according to our personal experience; a flow-chart for the therapeutic approach of difficult/aggressive acromegaly patients is proposed.

Real-life clinical impact of a five-tiered classification of pituitary tumors

INTRODUCTION

Usually benign, pituitary tumors (PT) can be invasive and aggressive with a propensity to progress and/or recur. Trouillas's clinicopathological classification attempts to predict the evolutionary risk of a PT. In this study, we assessed the prognostic value of this classification in an independent patient cohort and analyzed its impact on treatment strategies.

PATIENTS AND METHODS

In this study, 607 patients operated on between 2008 and 2018 for a PT were included. Grading was established based on invasion, proliferative activity (Ki-67, mitotic index) and p53 positivity. The therapeutic management following surgery was analyzed. Progression-free survival (PFS) of the graded tumors was estimated (Kaplan-Meier method and log-rank test) and a multivariate analysis was performed (Cox regression model).

RESULTS

Grading identified non-invasive PT without (grade 1a: 303 cases) or with proliferative activity (grade 1b: 53 cases) and invasive PT without (grade 2a: 202 cases) or with proliferative activity (grade 2b: 49 cases). The mean follow-up was 47 ± 30 months (median: 38 months). Progression/recurrence occurred in 127 cases. Grades were significant and independent predictors of PFS (P < 0.001) with a 4.8-fold higher risk of progression/recurrence in grade 2b as compared to grade 1a. As second-line therapy, gamma knife or conventional radiotherapy controlled tumor growth in 91.6 and 100% of cases, respectively, irrespective of the grade. Proliferative tumors exposed the patient to a 9.5-fold higher risk of having ≥3 adjuvant therapeutic lines as compared to non-proliferative tumors.

DISCUSSION

Grading of a PT according to Trouillas's classification predicts its risk of progression and should advocate for a personalized therapeutic approach in invasive and proliferative tumors.

SIGNIFICANCE STATEMENT

This is the first study to assess, on a cohort of 607 well-characterized patients, the real-life therapeutic impact of the five-tiered clinicopathological classification of pituitary tumors. First, we validate that pituitary tumor grades predict the evolutionary risk of the tumor, with a significant higher risk of progression/recurrence in invasive and/or proliferative tumors (mean follow-up: 47 ± 30 months, median: 38 months). Moreover, our study provides evidence that patients with proliferative tumors have a higher risk to be retreated after primary surgery and point toward the fact that radiotherapy can successfully control tumor growth in case of progression or recurrence. Our findings advocate for a personalized therapeutic approach in clinically aggressive pituitary tumors.

Clinical Biology of the Pituitary Adenoma

All endocrine glands are susceptible to neoplastic growth, yet the health consequences of these neoplasms differ between endocrine tissues. Pituitary neoplasms are highly prevalent and overwhelmingly benign, exhibiting a spectrum of diverse behaviors and impact on health. To understand the clinical biology of these common yet often innocuous neoplasms, we review pituitary physiology and adenoma epidemiology, pathophysiology, behavior, and clinical consequences. The anterior pituitary develops in response to a range of complex brain signals integrating with intrinsic ectodermal cell transcriptional events that together determine gland growth, cell type differentiation, and hormonal production, in turn maintaining optimal endocrine health. Pituitary adenomas occur in 10% of the population; however, the overwhelming majority remain harmless during life. Triggered by somatic or germline mutations, disease-causing adenomas manifest pathogenic mechanisms that disrupt intrapituitary signaling to promote benign cell proliferation associated with chromosomal instability. Cellular senescence acts as a mechanistic buffer protecting against malignant transformation, an extremely rare event. It is estimated that fewer than one-thousandth of all pituitary adenomas cause clinically significant disease. Adenomas variably and adversely affect morbidity and mortality depending on cell type, hormone secretory activity, and growth behavior. For most clinically apparent adenomas, multimodal therapy controlling hormone secretion and adenoma growth lead to improved quality of life and normalized mortality. The clinical biology of pituitary adenomas, and particularly their benign nature, stands in marked contrast to other tumors of the endocrine system, such as thyroid and neuroendocrine tumors.

Recommendations for the diagnosis and radiological follow-up of pituitary neuroendocrine tumours

Pituitary neuroendocrine tumours (PitNETs) constitute a heterogeneous group of tumours with a gradually increasing incidence, partly accounted for by more sensitive imaging techniques and more extensive experience in neuroradiology in this regard. Although most PitNETs are indolent, some exhibit aggressive behaviour, and recurrence may be seen after surgical removal. The changes introduced in the WHO classification in 2017 and terminological debates in relation to neuroendocrine tumours warrant an update of the guidelines for the diagnosis, preoperative and postoperative management, and follow-up of response to treatment of PitNETs. This multidisciplinary document, an initiative of the Neuroendocrinology area of the Sociedad Española de Endocrinología y Nutrición [Spanish Society of Endocrinology and Nutrition] (SEEN), focuses on neuroimaging studies for the diagnosis, prognosis and follow-up of PitNETs. The basic requirements and elements that should be covered by magnetic resonance imaging are described, and a minimum radiology report to aid clinicians in treatment decision-making is proposed. This work supplements the consensus between the Neuroendocrinology area of the SEEN and the Sociedad Española de Anatomía Patológica [Spanish Society of Pathology] (SEAP) for the pathological study of PitNETs.

A Convolutional Neural Network Model for Detecting Sellar Floor Destruction of Pituitary Adenoma on Magnetic Resonance Imaging Scans

Objective

Convolutional neural network (CNN) is designed for image classification and recognition with a multi-layer neural network. This study aimed to accurately assess sellar floor invasion (SFI) of pituitary adenoma (PA) using CNN.

Methods

A total of 1413 coronal and sagittal magnetic resonance images were collected from 695 patients with PAs. The enrolled images were divided into the invasive group (n = 530) and the non-invasive group (n = 883) according to the surgical observation of SFI. Before model training, 100 images were randomly selected for the external testing set. The remaining 1313 cases were randomly divided into the training and validation sets at a ratio of 80:20 for model training. Finally, the testing set was imported to evaluate the model performance.

Results

A CNN model with a 10-layer structure (6-layer convolution and 4-layer fully connected neural network) was constructed. After 1000 epoch of training, the model achieved high accuracy in identifying SFI (97.0 and 94.6% in the training and testing sets, respectively). The testing set presented excellent performance, with a model prediction accuracy of 96%, a sensitivity of 0.964, a specificity of 0.958, and an area under the receptor operator curve (AUC-ROC) value of 0.98. Four images in the testing set were misdiagnosed. Three images were misread with SFI (one with conchal type sphenoid sinus), and one image with a relatively intact sellar floor was not identified with SFI.

Conclusion

This study highlights the potential of the CNN model for the efficient assessment of PA invasion.

Chemotherapy of Capecitabine plus Temozolomide for Refractory Pituitary Adenoma after Tumor Resection and Its Impact on Serum Prolactin, IGF-1, and Growth Hormone

Objective

To investigate the efficiency of capecitabine (CAP) plus temozolomide (TEM) in refractory pituitary adenoma after tumor resection and its impact on serum prolactin (PRL), insulin-like growth factor 1 (IGF-1), and growth hormone (GH) levels.

Methods

From January 2017 to January 2020, 80 patients assessed for eligibility receiving transsphenoidal tumor resection for refractory pituitary adenoma in the Department of Neurosurgery of our hospital were recruited. They were randomly distributed at a ratio of 1 : 1 via the random number table method to receive either bromocriptine and TEM (control group) or bromocriptine plus combination chemotherapy of TEM and CAP (study group). The two groups were compared in terms of clinical efficacy and serum levels of PRL, IGF-1, and GH.

Results

The objective response rate (ORR) was 87.50% and 67.50% in the study group and the control group, respectively (P=0.032). Before treatment, two groups had similar levels of PRL, IGF-1, and GH. After treatment, PRL levels in the study group were lower than that in the control group (278.35 ± 39.25 versus 326.35 ± 42.45, P < 0.001). Compared with the control group, IGF-1 levels in the study group were also lower (311.78 ± 28.82 versus 364.35 ± 31.35, P < 0.001). The study group presented markedly lower levels of thyroid-stimulating hormone (TSH) and higher serum levels of free thyroxine-4 (FT-4) and adrenocorticotropic hormone (ACTH) versus the control group (P < 0.05). The incidence of adverse events was comparable between the study group (30.0%) and the control group (22.5%) (P > 0.05). All eligible patients had similar progression-free survival (PFS) after chemotherapy.

Conclusion

For patients with refractory pituitary adenoma, the combination chemotherapy of CAP and TEM significantly improves clinical outcomes and corrects hormonal disturbances, with a good safety profile, but its long-term efficacy requires further investigation.

Outcome of giant pituitary tumors requiring surgery

OBJECTIVE

The management of giant pituitary tumors is complex, with few publications and recommendations. Consequently, patient's care mainly relies on clinical experience. We report here a first large series of patients with giant pituitary tumors managed by a multidisciplinary expert team, focusing on treatments and outcome.

METHODS

A retrospective cohort study was conducted. Giant pituitary tumors were defined by a main diameter > 40mm. Macroprolactinomas sensitive to dopamine agonists were excluded. All patients were operated by a single neurosurgical team. After surgery, multimodal management was proposed, including hormone replacement, radiotherapy and anti-tumor medical therapies. Outcome was modeled using Kaplan-Meyer representation. A logistic regression model was built to identify the risk factors associated with surgical complications.

RESULTS

63 consecutive patients presented a giant adenoma, most often with visual defects. Patients were operated once, twice or three times in 59%, 40% and 1% of cases respectively, mainly through endoscopic endonasal approach. Giant adenomas included gonadotroph, corticotroph, somatotroph, lactotroph and mixed GH-PRL subtypes in 67%, 14%, 11%, 6% and 2% of patients respectively. Vision improved in 89% of patients with prior visual defects. Severe surgical complications occurred in 11% of patients, mainly for tumors > 50 mm requiring microscopic transcranial approach. Additional radiotherapy was needed for 29% of patients, 3 to 56 months after first surgery. For 6% of patients, Temozolomide treatment was required, 19 to 66 months after first surgery.

CONCLUSIONS

Giant pituitary tumors require multimodal management, with a central role of surgery. Most often, tumor control can be achieved by expert multidisciplinary teams.

Aggressive pituitary tumours and pituitary carcinomas

Although usually benign, anterior pituitary tumours occasionally exhibit aggressive behaviour, with invasion of surrounding tissues, rapid growth, resistance to conventional treatments and multiple recurrences. In very rare cases, they metastasize and are termed pituitary carcinomas. The time between a 'classical' pituitary tumour and a pituitary carcinoma can be years, which means that monitoring should be performed regularly in patients with clinical (invasion and/or tumour growth) or pathological (Ki67 index, mitotic count and/or p53 detection) markers suggesting aggressiveness. However, although both invasion and proliferation have prognostic value, such parameters cannot predict outcome or malignancy without metastasis. Future research should focus on the biology of both tumour cells and their microenvironment, hopefully with improved therapeutic outcomes. Currently, the initial therapeutic approach for aggressive pituitary tumours is generally to repeat surgery or radiotherapy in expert centres. Standard medical treatments usually have no effect on tumour progression but they can be maintained on a long-term basis to, at least partly, control hypersecretion. In cases where standard treatments prove ineffective, temozolomide, the sole formally recommended treatment, is effective in only one-third of patients. Personalized use of emerging therapies, including peptide receptor radionuclide therapy, angiogenesis-targeted therapy and immunotherapy, will hopefully improve the outcomes of patients with this severe condition.

Association of PTTG1 expression with invasiveness of non-functioning pituitary adenomas

Background

Pituitary tumor transforming gene 1 (PTTG1), paired-like homeodomain 2 (PITX2), and galectin-3 have been widely studied as predictive biomarkers for various tumors and are involved in tumorigenesis and tumor progression. We evaluated the usefulness of PTTG1, PITX2, and galectin-3 as predictive biomarkers for invasive non-functioning pituitary adenomas (NFPAs) by determining the relationship between the expressions of these three proteins and the invasiveness of the NFPAs. We also investigated whether PTTG1, E-cadherin, and Ki-67, which are known to be related to each other, show a correlation with NFPA features.

Methods

A retrospective study was conducted on 87 patients with NPFAs who underwent surgical removal. The NFPAs were classified into three groups based on magnetic resonance imaging findings of suprasellar extension and cavernous sinus invasion. Immunohistochemical staining for PTTG1, PITX2, galectin-3, E-cadherin, and Ki-67 was performed on tissue microarrays.

Results

PTTG1 expression showed a statistically significant correlation with the invasiveness of NFPAs, whereas PITX2 and galectin-3 did not have a relationship with the invasiveness of NFPAs. Moreover, there was no association among PTTG1, E-cadherin, and Ki-67 expression.

Conclusion

PTTG1 has the potential to serve as a predictive biomarker for invasive NFPA. Furthermore, this study may serve as a reference for the development of PTTG1-targeted therapeutic agents.

Pituitary Neoplasm Nomenclature Workshop: Does Adenoma Stand the Test of Time?

The WHO Classification of Endocrine Tumours designates pituitary neoplasms as adenomas. A proposed nomenclature change to pituitary neuroendocrine tumors (PitNETs) has been met with concern by some stakeholder groups. The Pituitary Society coordinated the Pituitary Neoplasm Nomenclature (PANOMEN) workshop to address the topic. Experts in pituitary developmental biology, pathology, neurosurgery, endocrinology, and oncology, including representatives nominated by the Endocrine Society, European Society of Endocrinology, European Neuroendocrine Association, Growth Hormone Research Society, and International Society of Pituitary Surgeons. Clinical epidemiology, disease phenotype, management, and prognosis of pituitary adenomas differ from that of most NETs. The vast majority of pituitary adenomas are benign and do not adversely impact life expectancy. A nomenclature change to PitNET does not address the main challenge of prognostic prediction, assigns an uncertain malignancy designation to benign pituitary adenomas, and may adversely affect patients. Due to pandemic restrictions, the workshop was conducted virtually, with audiovisual lectures and written précis on each topic provided to all participants. Feedback was collated and summarized by Content Chairs and discussed during a virtual writing meeting moderated by Session Chairs, which yielded an evidence-based draft document sent to all participants for review and approval. There is not yet a case for adopting the PitNET nomenclature. The PANOMEN Workshop recommends that the term adenoma be retained and that the topic be revisited as new evidence on pituitary neoplasm biology emerges.

Immune Landscape of Pituitary Tumors Reveals Association Between Macrophages and Gonadotroph Tumor Invasion

PURPOSE

Pituitary neuroendocrine tumors (PitNETs) are frequent intracranial neoplasms that present heterogenic characteristics. Little is known about the immune cell network that exists in PitNETs and its contribution to their aggressive behavior.

METHODS

Here we combined flow cytometry, t-SNE analysis, and histological approaches to define the immune landscape of surgically resected PitNETs. Xenografts of rodent pituitary tumor cells and resected PitNETs were performed in Rag2KO mice, in combination with in vitro analysis aimed at dissecting the role of pituitary tumor-cells in monocyte recruitment.

RESULTS

We report that gonadotroph PitNETs present an increased CD68+ macrophage signature compared to somatotroph, lactotroph, and corticotroph PitNETs. Transcriptomic and histological characterizations confirmed gonadotroph infiltrating macrophages expressed CD163, MRC-1, ARG1, and CSF1R M2 macrophage markers. Use of growth hormone (GH)3/GH4 somatotroph and LβT2/αT3.1 gonadotroph cells drove THP1 macrophage migration through respective expression of CCL5 or CSF1. Although both LβT2 and GH3 cells recruited F4/80 macrophages following their engraftment in mice, only LβT2 gonadotroph cells showed a capacity for M2-like polarization. Similar observations were performed on patient-derived xenografts from somatotroph and gonadotroph tumors. Analysis of clinical data further demonstrated a significant correlation between the percentage of CD68+ and CD163+ infiltrating macrophages and the invasive character of gonadotroph tumors.

CONCLUSIONS

Gonadotroph tumor drive the recruitment of macrophages and their subsequent polarization to an M2-like phenotype. More importantly, the association between infiltrating CD68+/CD163+ macrophages and the invasiveness of gonadotroph tumors points to macrophage-targeted immunotherapies being a potent strategy to limit the progression of gonadotroph PitNETs.

UPDATES IN AGGRESSIVE PITUITARY TUMORS

Aggressive pituitary tumors lie between pituitary adenomas and carcinomas, displaying a particular behavior, with invasion, resistance to conventional therapy and early recurrence. The radiological grading, along with prognostic markers such as Ki-67 proliferation index, p53, MGMT and transcription factors are important factors in establishing the benign, aggressive, or malignant nature of pituitary tumors, with a more accurate treatment strategy. In this article, we report the novelties in defining, classifying, and managing aggressive pituitary tumors and their malignant potential, focusing on clinicopathological, histological, molecular and radiological data.