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Biomedical subjects

H E Turner

Publications and source records attributed to H E Turner.

At least 19 recordsLinked to original sources
PubMed2005

Craniopharyngiomas in children and adults: systematic analysis of 121 cases with long-term follow-up.

BACKGROUND: Craniopharyngiomas account for 2-5% of all primary intracranial tumours. Despite their benign histological appearance, they are often associated with an unfavourable prognosis and their optimal treatment remains controversial. AIM: To analyse the natural history and treatment outcome of children and adults presenting to the Departments of Paediatrics and Endocrinology with craniopharyngioma between 1964 and 2003. PATIENTS AND METHODS: The records of 121 patients (age range 2.5-83 years, 42 aged < 16 and 79 aged > or = 16) were identified. The mean follow-up period since presentation was 103 months (8.6 years) (range 0.3-468 months). Sixteen patients underwent gross total removal (A), 3 gross total removal + radiotherapy (B), 51 partial removal (C), 33 partial removal + radiotherapy (D), 6 cyst evacuation alone (E) and 3 cyst evacuation + radiotherapy (F). The clinical, imaging and endocrinological data at presentation and during follow-up were analysed. RESULTS: Headache and visual field defects were the most common presenting clinical features (64% and 55%, respectively). Ninety-four per cent of the tumours had an extrasellar component and 23% of them were associated with hydrocephalus. There was a significant difference in the recurrence-free survival rates between groups A-D [at 10 years: 100% (A), 100% (B), 38% (C) and 77% (D), P < 0.01], which persisted even when analysing patients operated after 1980. The median time of first recurrence was 2.5 years (range 0.5-36). The peri-operative mortality of the patients who had any type of neurosurgical intervention due to recurrence was higher than that observed after primary surgery (24%vs. 1.8%) (P < 0.01). The rate of re-accumulation of the cyst fluid was 58% during the first year in patients of group E, whereas none of the subjects of group F experienced such an event during their follow-up period. There was no reversal of pre-existing pituitary hormone deficits after any surgical intervention. The probabilities of GH, FSH/LH, ACTH, TSH deficiency and diabetes insipidus at the 10-year follow-up were 88%, 90%, 86%, 80% and 65%, respectively. After excluding the non-tumour-related deaths, the 10-year survival rate following presentation was 90%. Patients with recurrence had a significantly lower probability for survival compared with those without it (at 10 years: 70%vs. 99%, P < 0.01). At the 10-year follow-up the probability of the presence of major visual field defects was 48%, hyperphagia/obesity 39%, epilepsy 12% and hemi-/monoparesis 11%. In this large series no substantial differences in the outcome of tumours diagnosed during childhood or adult life were found. CONCLUSIONS: Craniopharyngiomas remain tumours associated with significant morbidity. Gross total removal provides favourable results in terms of recurrences. If this cannot be achieved safely, adjuvant radiotherapy is beneficial in preventing tumour re-growth. Childhood- and adult-onset lesions generally behave similarly.

Adolescent↗
PubMed2004

Morphologic changes and molecular regulation of angiogenesis in pituitary adenomas.

Angiogenesis, the process of development of a new vasculature, plays a crucial role in tumour growth. In the pituitary, unlike other tissues, vascularization is lower in adenomas compared to the normal gland. Despite this finding, a relationship between increased vascularity and some aspects of tumour behaviour such as size, invasiveness, surgical outcome and malignancy, has been demonstrated. The process of angiogenesis is the result of a balance of stimulating and inhibiting factors. It is likely that an interaction between gene expression (such as pituitary tumour transforming gene), hormonal stimuli including oestrogens, corticosteroids, dopamine, 16-kDa fragments of prolactin and growth hormone, somatostatin analogues, and pro- and anti-angiogenic growth factors (e.g. vascular endothelial growth factor and fibroblast growth factor), determine the final angiogenic phenotype of pituitary tumours, and thus subsequent tumour behaviour.

Adenoma↗
PubMed2004

Angiogenesis and lymphangiogenesis in parathyroid proliferative lesions.

Angiogenesis and lymphangiogenesis are involved in tumoral growth and metastatic spread. There is little information on angiogenesis and no available data on lymphangiogenesis in parathyroid glands (PTG). Using immunohistochemistry for CD34, LYVE-1 (specific markers for vascular and lymphatic endothelium, respectively), vascular endothelial growth factor (VEGF)-A, VEGF-C, and fibroblast growth factor (FGF)-2, this study analyzes microvascular density (MVD), lymphatic vascular density (LVD), and expression of angiogenic and lymphangiogenic growth factors in 13 normal PTG, 77 parathyroid adenomas (PTA), and 17 primary parathyroid hyperplasia (PPH). MVD was higher in PPH and PTA, compared with PTG (P < 0.001). There was no difference in VEGF-A expression among groups. In contrast, FGF-2 expression was higher in PPH, compared with PTA and PTG (P < 0.0001). FGF-2 scores and MVD were significantly correlated (r = 0.43). LVD did not differ among groups, and VEGF-C expression was unrelated to LVD. There was no relationship between MVD and tumor behavior (adenoma size, PTH, or calcium). In conclusion, this study shows increased angiogenesis in parathyroid proliferative lesions compared with normal glands and suggests that FGF-2 is proangiogenic in parathyroid tissue. In PTA, tumor behavior is not related to angiogenic phenotype. This is the first demonstration of lymphatic vessels in PTG, but the lack of correlation with VEGF-C expression suggests that VEGF-C is not the primary lymphangiogenic factor.

Adenoma↗
PubMed2003

Non-functioning pituitary adenomas with positive immunoreactivity for ACTH behave more aggressively than ACTH immunonegative tumours but do not recur more frequently.

OBJECTIVES: Anecdotal reports have suggested that silent corticotroph tumours behave in an aggressive fashion; however, clear comparative data with other non-functioning adenomas (NFAs) are lacking. The aims of the study were, first, to review the natural history of those non-functioning pituitary adenomas with positive immunoreactivity for ACTH and secondly, to determine whether this subgroup behave more aggressively than ACTH immunonegative NFAs by means of comparison with existing departmental data. METHODS AND PATIENTS: Twenty-eight patients (16 men, mean age 51.3 years) who underwent transsphenoidal surgery in Oxford between 1975 and 2001 for clinically non-functioning adenomas where the subsequent immunostaining was positive for ACTH were identified from the patient database. All patients with silent corticotroph tumours who presented during this time period have been included in the analysis; three of the patients have subsequently died but none have been lost to follow-up. The mean follow-up period was 7.4 years (range 0.5-26.9 years) and the results were compared with departmental data for NFAs which were immunonegative for ACTH. None of the patients had clinical evidence of Cushing's syndrome. Tumour invasiveness was classified according to the modified Hardy criteria (Grade 1 = microadenoma (< 1 cm), Grade 2 = macroadenoma (> 1 cm) +/- suprasellar extension, Grade 3 = local invasion with bony destruction and tumour in sphenoid/cavernous sinus and Grade 4 = central nervous system (CNS) spread or extracranial spread, i.e. metastatic). Tumour recurrence was defined as an increase in tumour size compared with the first postoperative scan which was used as a baseline. Visual field defects were documented in 79% of the 28 patients at presentation compared to 69% in the non-functioning population as a whole (P = 0.3). The preoperative imaging in the silent corticotroph group (13 CT, 14 MRI and one air encephalogram) revealed 68% Grade 2 and 32% Grade 3 adenomas. RESULTS: The recurrence rate in the ACTH immunopositive tumours was 32% at a mean of 5.8 years (range 1-16 years) which was not significantly different from the 33% recurrence rate previously recorded in the ACTH immunonegative tumours (P = 0.9). Two of the patients with silent corticotroph adenomas have suffered multiple recurrences; one patient has had three operations and two courses of radiotherapy for two episodes of recurrence and one patient has had four operations, two courses of radiotherapy and gamma knife therapy after three recurrences in total. In contrast, no patient with an ACTH immunonegative tumour has required more than one course of treatment for tumour regrowth. CONCLUSIONS: This is the first single-centre comparative study of a series of clinically silent ACTH immunopositive tumours and has demonstrated that although they do not recur more often than ACTH immunonegative tumours, when they do regrow they show a more aggressive course. The practical implication of this is that there is no evidence for different postoperative imaging and radiotherapy protocols for ACTH immunopositive and immunonegative NFAs at initial presentation. However, if regrowth of a silent corticotroph tumour does occur then very careful monitoring is essential, after further treatment.

Adenoma↗
PubMed2003

Parathyroid adenomas and cardiovascular risk.

In recent decades, primary hyperparathyroidism (pHPT) has changed its clinical presentation from a disease with bone and renal involvement to a frequently asymptomatic disorder detected on routine biochemistry. Nevertheless, it remains unclear whether patients with untreated mild asymptomatic hyperparathyroidism are at risk for other complications such as increased morbidity and mortality from cardiovascular diseases. There are limited data on the incidence of cardiovascular abnormalities in mild pHPT. However, pHPT has been associated with increased risk of death from cardiovascular disease, hypertension, left ventricular hypertrophy (LVH), valvular and myocardial calcifications, impaired vascular reactivity, alterations in cardiac conduction, impaired glucose metabolism, dyslipidaemia, and alterations in body composition. The nature of some of these associations is in question, because cure of pHPT does not lead to improvement of the cardiovascular disorder e.g. hypertension. In contrast, currently available data suggest that LVH, impaired glucose metabolism and dyslipidaemia may improve after surgery and that successful parathyroidectomy could decrease the excess mortality in patients with pHPT due to cardiovascular disease.

Adenoma↗
PubMed2002

Undetectable postoperative cortisol does not always predict long-term remission in Cushing's disease: a single centre audit.

OBJECTIVE: An undetectable postoperative serum cortisol has been regarded as a definition of cure in Cushing's disease. However, we noted disease recurrence amongst patients with Cushing's disease despite undetectable postoperative cortisol levels, and this led us to audit our data. We have also previously assessed surgical outcome for acromegaly and microprolactinoma for a single surgeon. The aims of this study were two-fold: (i) to investigate the treatment and surgical outcome of patients with Cushing's disease. In particular, we wished to compare the data with outcome for other pituitary tumours in our centre; and (ii) to determine whether undetectable cortisol following surgery is predictive of long-term cure for Cushing's disease. PATIENTS AND METHODS: We performed a retrospective audit of 97 patients; mean age 39.1 (range: 14-82) years, 78/97 (80.4%) female, mean follow-up 92 months (range: 6 months to 29 years), with Cushing's disease seen in our unit between 1969 and 1998. We documented diagnostic investigation, immediate surgical outcome and disease recurrence in these patients. RESULTS: All patients had elevated urinary free cortisol (mean 1270.6 nmol/l, range: 327-3245 nmol/l). In total, 95.5% of patients did not suppress with low-dose dexamethasone suppression testing. Hypokalaemia (K < 3.2 mmol/l) was present in 15.6% of patients; 17.5% of patients did not show cortisol suppression with high-dose dexamethasone and 15.8% of patients did not show an ACTH rise of > 50% following corticotrophic releasing hormone (CRH) administration. There was no significant (> 3) gradient in ACTH or cortisol following CRH during inferior petrosal sinus sampling in 27.3% of patients who had the test. A pituitary tumour was demonstrated on imaging in 55.8% of patients; 10.3% were macroadenomas. Mortality rate following trans-sphenoidal surgery was 1%. Following surgery, the immediate postoperative remission rate (undetectable postoperative cortisol) was 68.5%. However, 11.5% of these patients developed disease recurrence during a mean follow-up period of 36.3 months. Considering microadenomas, Cushing's disease patients had an immediate postoperative remission rate of 63.2% which is significantly lower (P < 0.05) compared to a remission rate of 91.1% in acromegaly. Additionally, new postoperative gonadotrophin deficiency (13.9%) and TSH deficiency (25.8%) was higher in patients with Cushing's disease compared to patients with acromegaly or microprolactinoma. Immediate postoperative remission rates improved from 50% in the first decade of a surgeon's career to consistently above 60% in the second and third decades, demonstrating a trend which may be attributed to surgical experience. CONCLUSIONS: (i) Despite strict criteria for immediate postoperative remission and recurrence, undetectable postoperative cortisol is not always predictive of long-term remission. (ii) Despite an aggressive surgical approach, immediate postoperative remission rates for Cushing's disease are lower compared to other microadenomas. The development of new pituitary hormonal deficiency following surgery is also commoner than that seen amongst other microadenomas. These data have important implications for the follow-up of patients with Cushing's disease.

Adenoma↗
PubMed2002

Antiangiogenic effects of somatostatin analogues.

Inhibition of angiogenesis has become a target for antineoplastic therapy and for treatment of retinal neovascularization. The presence of somatostatin receptors on tumour cells and on the proliferating vascular endothelium has led to several in vitro and in vivo studies to investigate the antiproliferative and antiangiogenic effects of somatostatin analogues. Currently available data suggest that somatostatin analogues might inhibit angiogenesis directly through somatostatin receptors present on endothelial cells and also indirectly through the inhibition of growth factor secretion such as IGF-I and vascular endothelial growth factor (VEGF) and reducing monocyte chemotaxis. However, beneficial effects on inhibition of neovascularization have been questioned by some studies. More work is therefore required to firmly establish the role of somatostatin analogues as potential antiangiogenic therapy. The currently available somatostatin analogues have high affinity for somatostatin receptor subtype 2 (sst2) and, to a lesser extent, sst5 and sst3. However, because vascular endothelial cells express several types of somatostatin receptors, it will be important to investigate somatostatin analogues with different receptor subtype affinities, which might increase the spectrum of available therapy for tumours.

Angiogenesis Inhibitors↗
PubMed2002

Primary medical therapy for acromegaly: an open, prospective, multicenter study of the effects of subcutaneous and intramuscular slow-release octreotide on growth hormone, insulin-like growth factor-I, and tumor size.

Conventional surgery and radiotherapy for acromegaly have limitations. There are few data on the use of the somatostatin analog octreotide (Oct) as primary medical therapy. An open prospective study of 27 patients with newly diagnosed acromegaly was conducted in nine endocrine centers in the United Kingdom. Twenty patients had macroadenomas, and 7 had microadenomas. For the first 24 wk (phase 1), patients received sc Oct in an initial dose of 100 microg, 3 times daily, increased to 200 micro g three times daily after 4 wk in the 13 patients whose mean serum GH remained greater than 5 mU/liter (2 microg/liter). Five-point GH profiles were performed at 0, 4, 12, and 24 wk, and high resolution pituitary imaging using a standard protocol was performed at 0, 12, and 24 wk (magnetic resonance imaging in 25 patients and computed tomography in 2). Tumor dimensions and volumes were calculated by a central, reporting neuroradiologist, and the results were audited by a second, independent neuroradiologist. After 24 wk, 15 patients proceeded to phase 2 of the study with a direct switch to monthly injections of the depot formulation of Oct, Sandostatin long-acting release (Oct-LAR). Further GH profiles were performed at 36 and 48 wk, and pituitary imaging was performed at 48 wk. The median pretreatment serum GH concentration was 30.7 mU/liter (range, 6.7-141.4). During sc Oct, serum GH fell to less than 5 mU/liter in 9 patients (38%), and IGF-I fell to normal in 8 patients (33%). All 27 tumors shrank during sc Oct; for microadenomas the median tumor volume reduction was 49% (range, 12-73), and for macroadenomas it was 43% (range, 6-92). After 24 wk of Oct-LAR (end of phase 2), the GH level was less than 5 mU/liter in 11 of 14 patients (79%), and IGF-I was normal in 8 of 15 patients (53%). In the 15 patients given Oct-LAR (10 macroadenomas), wk 48 scans showed a further overall median tumor volume reduction of 24%. At the end of the study 79% of patients had mean serum GH levels below 5 mU/liter, 53% had normal IGF-I levels, and 73% showed greater than 30% tumor shrinkage. Twenty-nine percent of patients achieved all 3 targets, but no patient with pretreatment GH levels above 50 mU/liter did so at any stage of the study. Primary medical therapy with Oct offers the prospect of normalization of GH/IGF-I levels together with substantial tumor shrinkage in a significant subset of acromegalic patients. This is most likely to occur in patients with pretreatment GH levels less than 50 mU/liter (20 microg/liter).

Acromegaly↗
PubMed2000

The use of fixed-mixture insulins in clinical practice.

BACKGROUND: Pre-mixed insulins currently represent about 40% of the world market in human insulin. Despite the fact that many patients are being treated with these insulin formulations, there are surprisingly few data about fixed mixtures and comparisons with other administration schedules. The main advantages of using a pre-mixed preparation over a self-mixed insulin are increased accuracy of dosage, efficacy and patient convenience. These benefits may lead to increased compliance resulting in better long-term control of the disease. Insulin mixtures are used by a wide variety of patients with type-1 and type-2 diabetes. Pre-mixed insulins also appear to be useful in elderly and adolescent patients with diabetes, although there are few published data on patients in these groups. CONCLUSIONS: It is likely that, in the future, fixed mixtures containing rapid-acting insulin analogues, such as insulin lispro, and possibly newly formulated intermediate-acting insulin analogues, such as neutral protamine lispro, may allow further improvements in both metabolic control and patient convenience.

Adolescent↗
PubMed2000

Expression analysis of cyclins in pituitary adenomas and the normal pituitary gland.

OBJECTIVES: The molecular events involved in pituitary tumour development are still poorly understood. The cyclins play an important role in the control of the cell cycle during cell proliferation and over-expression of the cyclins has been shown in many different tumour types. The aim of this study was to investigate whether, in comparison to the normal gland, ectopic expression of cyclins occurs in pituitary tumours, and whether differences in cyclin expression are seen with different pituitary tumour types or in association with different tumour behaviour. In contrast to work on cyclin D there are no published data on cyclin B, A and E in human pituitary tumours. METHODS: Sixty-seven surgically removed pituitary tumours and 10 specimens of normal human anterior gland were studied using immunohistochemistry to detect the nuclear expression of cyclin A, B, D and E. The microvascular density (as a measure of angiogenesis), Ki-67 labelling index (to assess cell proliferation) and bcl-2 expression had previously been investigated in this cohort. RESULTS: All tumours studied contained cells that immunostained positively for cyclin A, B, D and E. However the proportion of positive cells in each tumour type was different. In contrast, there were no cyclin D positive cells in the normal anterior pituitary gland studied, and labelling indices (LI) for cyclins A, B and E were significantly lower in the normal gland than in pituitary adenomas. The cyclin LIs for A, B, D and E were significantly higher in macroadenomas when compared to microadenomas. Non-functioning pituitary tumours (NFA) generally showed the highest cyclin LI. In particular, both recurrent and nonrecurrent NFA showed significantly higher cyclin D LI than other tumours. The ratio of cells expressing cyclin B compared to those expressing cyclin A was significantly higher in functionless tumours that regrew when compared to NFAs that did not (P<0.05). Cyclin D LI and the overall Ki-67 LI as a measure of cell proliferation were related (R2 = 11.4, P = 0.0033) and bcl-2 positive tumours had significantly higher cyclin D LI compared with bcl-2 negative tumours. There was a weak relationship between angiogenesis and the relative proportion of cells expressing D when compared to those in S phase (D/A ratio) (r2 = 10.5, P = 0.02). CONCLUSIONS: We have demonstrated that ectopic expression of cyclin D and over-expression of cyclins A, B and E, regulating different stages of the cell cycle is common in pituitary adenomas. In addition, cyclin expression was related to size and to pituitary tumour regrowth. The differences between functionless tumours that regrow and those that do not, may be due to reduced bcl-2 expression, increased cell proliferation, more cells at the G2/M stage (B/A ratio) and reduced cell differentiation with more aggressive subsequent tumour behaviour. Cyclin D expression and cell proliferation were related indicating that the cells entering the cycle become 'committed' to cell cycle progression. There was no relative over-expression of individual cyclins, and therefore no evidence of relative increase in cell cycle phase, indicating that the increased cyclin expression is more likely to be due to constant mitogenic stimulation rather than cell cycle regulatory failure. Although nuclear cyclin expression is a good marker of tumour growth and aggressive behaviour, the growth signal that leads to cyclin expression remains to be identified.

Adenoma↗
PubMed2000

Proliferation, bcl-2 expression and angiogenesis in pituitary adenomas: relationship to tumour behaviour.

The prediction of pituitary tumour behaviour, in terms of response to treatment from which can be derived optimal management strategies, is a challenge that has been approached using several different means. Angiogenesis in other tumour types has been shown to be correlated with poor response to treatment and tumour recurrence. The aim of this paper is to assess the role of measurements of cell proliferation and angiogenesis in predicting pituitary tumour behaviour. The proliferative capacity of the tumour was assessed using the Ki-67 labelling index (LI) while bcl-2 expression was used to assess anti-apoptotic pathways. The microvessel density (MVD) was assessed using antibodies to CD31 and factor VIII-related antigen, and with biotinylated ulex europaeus agglutinin I. There was no difference between Ki-67 LI and MVD of functionless tumours that recurred and those that did not, but bcl-2 expression was significantly lower in tumours that subsequently regrew. Macroprolactinomas had significantly higher LI than microprolactinomas and than all other tumours. Cell proliferation and angiogenesis were not related, showing that both processes are under different control mechanisms in pituitary tumours. In contrast there was a positive relationship between markers of angiogenesis and bcl-2 expression in prolactinomas, GH-secreting tumours and non-recurrent functionless tumours with higher levels of bcl-2 expression being found in the more vascular tumours. These findings may suggest that angiogenesis is related to the ability of tumour cells to survive rather than their proliferative activity.

Adenoma↗
PubMed2000

Angiogenesis in pituitary adenomas and the normal pituitary gland.

Angiogenesis is essential for tumor growth beyond a few millimeters in diameter, and the intratumoral microvessel count that represents a measure of angiogenesis has been correlated with tumor behavior in a variety of different tumor types. To date no systematic study has assessed pituitary tumors of different secretory types, correlating vascular count with tumor size. The vascular densities of pituitary tumors and normal anterior pituitary were therefore assessed by counting vessels labeled using the vascular markers CD31 and ulex europaeus agglutinin I. One hundred and twelve surgically removed pituitary adenomas (30 GH-secreting, 25 prolactinomas, 15 ACTH-secreting, and 42 nonfunctioning tumors) were compared with 13 specimens of normal anterior pituitary gland. The vascular counts in the normal anterior pituitary gland were significantly higher (P < 0.05) than those in the tumors using both CD31 and ulex europaeus agglutinin I. In addition, microprolactinomas were significantly less vascular (P < 0.05) than macroprolactinomas, although there was no such difference between vascular densities of microadenomas and macroadenomas producing GH. ACTH-secreting tumors were, like microprolactinomas, of much lower vascular density than the normal pituitary and other secreting and nonsecreting tumor types. In marked contrast to other tumors, pituitary adenomas are less vascular than the normal pituitary gland, suggesting that there may be inhibitors of angiogenesis that play an important role in the behavior of these tumors.

Adenoma↗
PubMed2000

Role of matrix metalloproteinase 9 in pituitary tumor behavior.

The matrix metalloproteinases (MMPs) are a family of zinc-containing endopeptidases that are able to degrade the extracellular matrix and allow angiogenesis and tumor invasion. The vast majority of pituitary tumors are benign and do not metastasize to distant sites, although they may invade locally. The aim of this study was to determine whether expression of the collagenase MMP-9 may play a role in allowing angiogenesis and invasion by different pituitary tumor types. Tumor expression of MMP-9 was investigated using a monoclonal antibody on a series of well-characterized paraffin-embedded sections of pituitary tumors. Invasive macroprolactinomas (n = 11) were significantly more likely to express MMP-9 than noninvasive macroprolactinomas (n = 8) (P = 0.003). Invasive macroprolactinomas showed higher-density MMP-9 staining than noninvasive tumors (P < 0.05). MMP-9 expression did not differ between noninvasive tumors and normal pituitary gland, or between different sized prolactinomas. MMP-9 expression was related to aggressive tumor behavior. It was higher in invasive macroprolactinomas (P = 0.003) when compared with noninvasive macroprolactinomas or the normal anterior pituitary gland. In addition, although there was no difference in whether MMP-9 was present or not when nonfunctioning adenomas that recurred were compared with those that did not, samples of recurrent tumor at the second presentation were more likely to express MMP-9 (P = 0.01). Pituitary carcinomas were significantly more likely to be MMP-9 positive compared with normal anterior pituitary gland (P = 0.05), but there was no difference from invasive adenomas. Angiogenesis assessed by vascular density was related to MMP-9 expression (P < 0.05). In summary, we have shown the presence of MMP-9 expression in some invasive and recurrent pituitary adenomas, and in the majority of pituitary carcinoma. The mechanisms whereby MMP-9 expression influences tumor recurrence and invasiveness, and its association with angiogenesis, remains to be elucidated. However, these observations suggest that a future potential therapeutic strategy for some pituitary tumors may be administration of a synthetic MMP-9 inhibitor.

Adenoma↗
PubMed2000

Angiogenesis in pituitary adenomas - relationship to endocrine function, treatment and outcome.

Angiogenesis has been shown to be related to tumour behaviour, prognosis and response to treatment in many different tumour types. The aim of this study was to examine the relationship between angiogenesis and tumour behaviour and response to treatment in pituitary adenomas. The microvessel density (MVD) of pituitary tumours was assessed by counting blood vessels labelled with 3 different endothelial markers using antibodies to CD31, factor eight-related antigen and biotinylated Ulex europaeus (agglutinin I UEAI). One hundred and forty-two surgically removed pituitary adenomas (46 GH secreting, 6 microprolactinomas, 19 macroprolactinomas, 18 ACTH secreting and 53 functionless tumours) were carefully characterized and assessed. There was a significant negative correlation between age and MVD of GH secreting tumours (R(2)=33.8, P=0.005). Age was not related to MVD in other tumour types. Pre-treatment hormone production by the adenomas was related to MVD in prolactinomas (P<0.05), but not in GH secreting tumours. Invasive prolactinomas were significantly more vascular than non-invasive tumours (P<0.05). Drug treatment with metyrapone or bromocriptine did not appear to influence tumour angiogenesis. Surgical cure was more likely in macroprolactinomas and in ACTH secreting tumours with lower MVD. These results show that factors related to angiogenesis are very important in determining a number of clinical features of pituitary tumours, in particular the invasiveness of macroprolactinomas, the effect of age in tumours secreting GH and the outcome of surgical treatment in macroprolactinomas and ACTH secreting tumours.

Adenoma↗
PubMed1999

Are markers of proliferation valuable in the histological assessment of pituitary tumours?

The prediction of tumour behaviour and response to treatment has led to interest in the assessment of the proliferative potential of tumours. Pituitary tumours are usually histologically benign but are capable of aggressive growth and local invasion, although distant metastasis is limited to the very rare pituitary carcinoma. These differences in tumour behaviour may determine both the prognosis and also the effectiveness of treatment whether it be surgery, drugs or radiotherapy. Immunohistochemistry using antibodies to Ki-67 and proliferating cell nuclear antigen (PCNA) which are expressed in cells that have entered the cell cycle, can be used to assess the proportion of the cells from a tumour that are proliferating. The percentage of positively stained nuclei (labelling index (LI)) may be helpful in predicting appropriate management, as there is a relationship in many tumours between labelling index, invasiveness and tumour recurrence. This has been shown to be true for pituitary tumours, although there may be significant overlap such that low LI may be seen in the rare, aggressive, metastatic pituitary carcinomas, and high LI in indolent tumours. Thus although assessment of proliferation may be helpful in arousing suspicion as to subsequent tumour recurrence or invasiveness, this technique also demonstrates that there are other important and as yet unidentified processes that determine pituitary tumour behaviour.

Bromodeoxyuridine↗