A heritable predisposition to pituitary tumors

The Clinical Features and Molecular Mechanism of Pituitary Adenoma Associated With Vestibular Schwannoma

OBJECTIVES

To explore the clinical features and mechanism of pituitary adenoma associated with vestibular schwannoma (PAVS).

PATIENTS AND METHODS

The authors retrospectively reviewed pituitary adenoma patients in Beijing Tiantan Hospital from January 1, 2008 to December 31, 2016. A total of two pituitary adenoma samples, 1 vestibular schwannoma sample and one paired pituitary adenoma/blood sample were subjected next-generation sequencing and sanger sequence.

RESULTS

A total of 5675 pituitary adenoma patients from January 1, 2008 to December 31, 2016, were retrospectively analyzed; of these, 4 (7%) patients met the criteria of PAVS. Clinical variable analyses revealed significant correlations between PAVS and older age when compared with sporadic pituitary adenoma (SPA) or sporadic vestibular schwannoma (SVS). The authors found that there were 2 germline mutations of XKR3 in 2/4 PAVS patients. Therefore, the authors speculated that XKR3 might be a genetic predisposition factor. The result also showed that there was no NF2 mutation and NF2-related symptom in the 4 PAVS samples.

CONCLUSIONS

PAVS had a significant correlation with older age when compared with SPA and SVS. XKR3 may be a genetic predisposition factor for PAVS, it represents a therapeutic target for PAVS in the future.

Large Scale Molecular Studies of Pituitary Neuroendocrine Tumors: Novel Markers, Mechanisms and Translational Perspectives

Simple Summary

Pituitary neuroendocrine tumors are non-cancerous tumors of the pituitary gland, that may overproduce hormones leading to serious health conditions or due to tumor size cause chronic headache, vertigo or visual impairment. In recent years pituitary neuroendocrine tumors are studied with the latest molecular biology methods that simultaneously investigate a large number of factors to understand the mechanisms of how these tumors develop and how they could be diagnosed or treated. In this review article, we have studied literature reports, compiled information and described molecular factors that could affect the development and clinical characteristics of pituitary neuroendocrine tumors, discovered factors that overlap between several studies using large scale molecular analysis and interpreted the potential involvement of these factors in pituitary tumor development. Overall, this study provides a valuable resource for understanding the biology of pituitary neuroendocrine tumors.

Abstract

Pituitary neuroendocrine tumors (PitNETs) are non-metastatic neoplasms of the pituitary, which overproduce hormones leading to systemic disorders, or tumor mass effects causing headaches, vertigo or visual impairment. Recently, PitNETs have been investigated in large scale (exome and genome) molecular analyses (transcriptome microarrays and sequencing), to uncover novel markers. We performed a literature analysis on these studies to summarize the research data and extrapolate overlapping gene candidates, biomarkers, and molecular mechanisms. We observed a tendency in samples with driver mutations (GNAS, USP8) to have a smaller overall mutational rate, suggesting driver-promoted tumorigenesis, potentially changing transcriptome profiles in tumors. However, direct links from drivers to signaling pathways altered in PitNETs (Notch, Wnt, TGF-β, and cell cycle regulators) require further investigation. Modern technologies have also identified circulating nucleic acids, and pinpointed these as novel PitNET markers, i.e., miR-143-3p, miR-16-5p, miR-145-5p, and let-7g-5p, therefore these molecules must be investigated in the future translational studies. Overall, large-scale molecular studies have provided key insight into the molecular mechanisms behind PitNET pathogenesis, highlighting previously reported molecular markers, bringing new candidates into the research field, and reapplying traditional perspectives to newly discovered molecular mechanisms.

Cost-effectiveness of acromegaly treatments: a systematic review

PURPOSE

Acromegaly is a rare disease that results in the enlargement of body extremities and in organomegaly. Treatments include surgery, drugs, and radiotherapy, which are all onerous. Therefore, well-conducted cost-analyses are crucial in the decision-making process.

METHODS

A systematic review of cost-effectiveness studies on acromegaly therapies was performed following PRISMA and Cochrane recommendations. The search for records was conducted in PubMed, Scopus, and Web of Science (May 2018). The quality of the included studies was assessed using the Joana Briggs Institute Tool.

RESULTS

From initial 547 records, 16 studies were included in the review. The studies could present more than one economic evaluation, and encompassed cost-effectiveness (n = 13), cost-utility (n = 5), and cost-consequence (n = 1) analyses. All studies were model-based and evaluated only direct medical costs. Eleven records did not mention discounting and only 10 performed sensitivity analyses. The characteristic of the studies, the cost-effectiveness results and the studies' conclusions are described and commented upon. The main limitation of the studies was discussed and aspects to improve in future studies were pointed out.

CONCLUSIONS

Cost-effectiveness studies on acromegaly have been performed in several scenarios, evaluating different phases of treatment. However, the studies present limitations and, overall, were considered of moderate quality. Further economic models should be developed following health economics guidelines recommendations, and must improve transparency.

Polymorphisms in MEN1 and DRD2 genes are associated with the occurrence and characteristics of pituitary adenomas

OBJECTIVE

Although pituitary adenomas (PAs) affect a significant proportion of the population, only a fraction have the potential to become clinically relevant during an individual's lifetime, causing hormonal imbalance or complications due to mass effect. The overwhelming majority of cases are sporadic and without a clear familial history, and the genotype-phenotype correlation in PA patients is poorly understood. Our aim was to investigate the involvement of genes known for their role in familial cases on drug response and tumor suppression in the development and pathology of PAs in a patient group from Latvia.

DESIGN

The study included 143 cases and 354 controls, we investigated the role of single-nucleotide polymorphisms (SNPs) in seven genes (SSTR2, SSTR5, DRD2, MEN1, AIP, GNAS, and PRKAR1A) associated with pituitary tumor occurrence, phenotype, and clinical symptoms.

METHODS

Genotyping of 96 tag and nonsynonymous SNPs was performed in the genomic regions of interest.

RESULTS

We discovered a significant association (OR=17.8, CI 0.95=2.18-145.5, P=0.0002) between a rare MEN1 mutation (rs2959656) and clinically active adenoma in our patients. Additionally, rs7131056 at DRD2 was associated with a higher occurrence of extrasellar growth in patients with prolactinoma and somatotropinoma (OR=2.79, CI 0.95=1.58-4.95, P=0.0004).

CONCLUSIONS

rs2959656, a nonsynonymous variant in MEN1, is associated with the development of clinically active PA. Furthermore, rs7131056 in DRD2 contributes to either faster growth of the adenoma or reduced symptomatic presentation, allowing PAs to become larger before detection.

Vestibular schwannoma and pituitary adenoma in the same patient: coincidence or novel clinical association?

Over the years the authors have evaluated a number of patients with vestibular schwannomas (VS) who have also been diagnosed with a pituitary adenoma (PA). No associations between these tumors have been established to date. The objective of the current study is to investigate the epidemiological association between VS and PA via a population-based study and to supplement these data with a retrospective case series of 12 patients who were evaluated at the authors' center over the past 15 years. An analysis of the Surveillance, Epidemiology, and End Results database including all patients identified with a diagnosis of VS and/or PA was performed. A comparison between the observed and expected annual incidence was calculated and population differences between those with VS + PA were compared with single tumor populations. 9888 patients with VS and 26,577 patients with PA were identified among 822.9 million person-years. Within these populations, 31 patients were diagnosed with both tumor types. Overall, 1 in every 319 patients with VS was also diagnosed with a PA. The average annual incidence for VS was 1.2 per 100,000 persons per year while the average PA rate was 3.2 per 100,000 persons per year. The observed rate of co-incident VS and PA was greater than what is expected by chance alone assuming independence. The cohort of patients with coexisting VS and PA were older and more commonly male compared to VS-only or PA-only groups. These data strongly suggest that a common environmental or genetic predisposition exists for VS and PA development. Further study of this population may help elucidate the cause of tumorigenesis in a subset of patients with seemingly sporadic tumors.

Common variants at 10p12.31, 10q21.1 and 13q12.13 are associated with sporadic pituitary adenoma

Pituitary adenoma is one of the most common intracranial neoplasms, and its genetic basis remains largely unknown. To identify genetic susceptibility loci for sporadic pituitary adenoma, we performed a three-stage genome-wide association study (GWAS) in the Han Chinese population. We first analyzed genome-wide SNP data in 771 pituitary adenoma cases and 2,788 controls and then carried forward the promising variants for replication in another 2 independent sets (2,542 cases and 3,620 controls in total). We identified three new susceptibility loci below the genome-wide significance threshold (P < 5 × 10(-8)) in the combined analyses: 10p12.31 (rs2359536, P(meta) = 2.25 × 10(-10) and rs10828088, P(meta) = 6.27 × 10(-10)), 10q21.1 (rs10763170, P(meta) = 6.88 × 10(-10)) and 13q12.13 (rs17083838, P(meta) = 1.89 × 10(-8)). This study is the first GWAS to our knowledge on sporadic pituitary adenoma, and our results provide insight into the genetic basis of this disease.

Co-prevalence of other tumors in patients harboring pituitary tumors

Object

The cause of most pituitary tumors remains unknown, although a genetic contribution is recognized for some. The prevalence of pituitary tumors in the general population is high. Analyzing the Utah Population Database (UPDB), the authors investigated the co-prevalence of other independent primary tumors in patients with known pituitary tumors, both benign and malignant, and in the relatives of these patients.

Methods

The authors identified individuals in the Utah Cancer Registry diagnosed with pituitary tumors who also had genealogy data in the UPDB and then calculated relative risks (RRs) of other tumors in these patients and their relatives.

Results

Among the 591 individuals with pituitary tumors, 16 (2.7%) had a malignant pituitary tumor and 77 (13%) had independent primary tumors of other origin. Overall, this is significantly higher than expected (70.6 expected, p = 0.009) within the general population (RR = 1.32, 95% CI 1.06–1.61). A significant excess for several different cancer sites was observed among the first-, second-, and third-degree relatives of the cases, including prostate and other cancers. Independent primary tumors at other sites have markedly elevated co-prevalence in patients harboring pituitary tumors and among their close and distant relatives.

Conclusions

This information will prove useful for counseling patients in whom pituitary tumors have been diagnosed and suggests strong genetic or environmental co-risks for the development of other tumors.

Epidemiology and etiopathogenesis of pituitary adenomas

Pituitary adenomas are usually benign monoclonal tumours presenting either due to hypersecretion of pituitary hormones, and/or due to local space occupying effects and hyposecretion of some or all of the pituitary hormones. Some pituitary adenomas cause prominent symptoms, while others may result in slowly developing, insidious, non-specific complains delaying accurate diagnosis, with a third group remaining symptomless and recognised only incidentally. Therefore, it is a challenge to accurately determine the prevalence and incidence of pituitary adenomas in the general population. The vast majority of pituitary adenomas occur sporadically, but familial cases are now increasingly recognised. Hereditary predisposition, somatic mutations and endocrine factors were shown to have a pathophysiologic role in the initiation and progression of pituitary adenomas, which interestingly almost always remain benign. Here, we summarize the available epidemiological data and the known pathogenesis of the pituitary adenomas.

Familial isolated pituitary adenomas: an emerging clinical entity

Familial pituitary tumors are increasingly recognized. While some of these cases are related to wellknown syndromic conditions such as multiple endocrine neoplasia type 1 (MEN1) or Carney complex, others belong to the familial isolated pituitary adenoma (FIPA) patient group. The discovery of heterozygous, loss-of-function germline mutations in the gene encoding the aryl hydrocarbon receptor interacting protein (AIP) in 2006 has subsequently enabled the identification of a mutation in this gene in 20% of FIPA families and 20% of childhood-onset simplex soma- totroph adenomas. The exact mechanism by which the lack of AIP leads to pituitary adenomas is not clear. AIP mutations cause a low penetrance autosomal dominant disease with often a distinct phenotype characterized by young-onset, aggressive, large GH, mixed GH and PRL or PRL-secreting adenomas. This review aims to summarize currently available clinical data on AIP mutation-positive and negative FIPA patients.

Familial pituitary adenomas - who should be tested for AIP mutations?

Familial Isolated Pituitary Adenomas (FIPA), an autosomal dominant disease with low penetrance is being increasingly recognized. FIPA families can be divided into two distinct groups based on genetic and phenotypic features. Patients with mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene are characterized by young-onset somatotroph or lactotroph macroadenomas, while in the other, larger group of FIPA patients with typically adult-onset disease and more varied adenoma types, no causative gene(s) has been identified. Young-onset macroadenoma patients can also be identified with germline AIP mutation without an apparent family history. Further data and longer follow-up are necessary to establish formal guidelines, but the current data suggest genetic screening of the AIP gene in patients with a pituitary adenoma and no other associated features who have (i) a family history of pituitary adenoma, (ii) childhood-onset pituitary adenoma or (iii) a pituitary somatotroph or lactotroph macroadenoma diagnosed before the age of 30 years.

Incidental pituitary adenomas

Object

Pituitary incidentalomas are a common finding with a poorly understood natural history. Over the last few decades, numerous studies have sought to decipher the optimal evaluation and treatment of these lesions. This paper aims to elucidate the current evidence regarding their prevalence, natural history, evaluation, and management.

Methods

A search of articles on PubMed (National Library of Medicine) and reference lists of all relevant articles was conducted to identify all studies pertaining to the incidence, natural history, workup, treatment, and follow-up of incidental pituitary and sellar lesions, nonfunctioning pituitary adenomas, and incidentalomas.

Results

The reported prevalence of pituitary incidentalomas has increased significantly in recent years. A complete history, physical, and endocrinological workup with formal visual field testing in the event of optic apparatus involvement constitutes the basics of the initial evaluation. Although data regarding the natural history of pituitary incidentalomas remain sparse, they seem to suggest that progression to pituitary apoplexy (0.6/100 patient-years), visual field deficits (0.6/100 patient-years), and endocrine dysfunction (0.8/100 patient-years) remains low. In larger lesions, apoplexy risk may be higher.

Conclusions

While the majority of pituitary incidentalomas can be managed conservatively, involvement of the optic apparatus, endocrine dysfunction, ophthalmological symptoms, and progressive increase in size represent the main indications for surgery.

Genetic susceptibility in pituitary adenomas: from pathogenesis to clinical implications

Pituitary adenomas usually present sporadically, with a multifactorial pathogenesis including somatic mutational events in cancer-related genes. Genetic predisposition implies the presence of germline DNA alterations with a range of impacts on pituitary cell biology, translating into a variable penetrance of the disease. Genetic causes must be considered in the presence of specific clinical settings, such as familial occurrence of pituitary adenoma, with or without extrapituitary diseases, and may also be suspected in young patients (<30 years of age) with macroadenomas. We review the clinical implications of genetic predisposition, with special attention on multiple endocrine neoplasia type 1, Carney complex and familial isolated pituitary adenoma. Genetic screening in selected patients with an apparently sporadic disease is also discussed.