A comparison of proliferation indices in human anterior pituitary adenomas using formalin-fixed tissue and in vitro cell culture

Ki67 in endocrine neoplasms: to count or not to count, this is the question! A systematic review from the English language literature

BACKGROUND

Endocrine neoplasms are generally slow-growing tumors that can show hormonal activity and give metastases. In most cases they are benign and clearly malignant forms are easy to diagnose. However, borderline forms may occur and be, for the pathologists, very difficult to classify. In these cases, there is a strong need to identify factors that may aid. Official classification systems for endocrine neoplasms are based on the evaluation of proliferation and, in most cases, they rely on mitotic count. In support, the study of Ki67 is carried out which, however, has not yet been included in any official classification system, except for neuroendocrine neoplasms of the gastro-entero-pancreatic tract.

PURPOSE

The aim of the present study was to investigate the proven or unproven role of Ki67 in endocrine neoplasms, in different districts, in order to bring to light the substantial differences, in terms of proliferation, existing between neoplasms so similar, but at the same time, so different.

METHODS

A thorough search of English language literature was performed, looking for articles concerning Ki67 in five endocrine neoplasms (pituitary adenomas, thyroid neoplasms, adrenocortical neoplasms, pheochromocytomas and paragangliomas).

RESULTS

From 2170, 236 articles were selected and it was seen that the endocrine neoplasm in which Ki67 was most studied was the pituitary, where it still shows a controversial role. In other neoplasms different roles were identified.

CONCLUSION

The pathologist should be aware of the contribution that this proliferative marker can give to the diagnosis and, sometimes, to the therapy selection, for the clinician.

Expression of BCL-2, BAX and P53 Proteins in Pituitary Adenomas an Immunohistochemical Study

Aims and Background

Although pituitary adenomas are usually benign lesions, their growth rate is highly variable and unpredictable. Apoptosis appears to be an important process in neoplastic lesions. The purpose of this study was to investigate the expression of apoptosis-related proteins including Bcl-2, bax and p53 in pituitary adenomas and its correlation with hormone function, tumor size, local control, and proliferative activity.

Study Design

The expression of Bcl-2, Bax and p53 proteins and hormonal function were determined in formalin-fixed, paraffin-embedded tissue from 41 untreated pituitary adenomas using immunohistochemistry. The patients were followed for a median of 60 months (range, 12 to 95). Patient charts were reviewed to record tumor recurrence and size. Tumor proliferative activity was assessed by immunohistochemistry using Ki-67 antibody.

Results

Of 41 pituitary adenomas, 26 (63%) were hormone-secreting and 15 (37%) non-functioning, 34 (83%) were macroadenoma and 7 (17%) microadenoma, and 15 (37%) showed local relapse. Six (14%) adenomas were of low proliferative activity, whereas the others (86%) were non-proliferative. Immunohistochemically, 31 adenomas (75%) showed bcl-2 positivity, 37 (90%) bax positivity, and 7 (17%) p53 positivity. Statistical analysis revealed that Bcl-2 protein expression significantly diminished in prolactin-secreting and non-functioning adenomas (P = 0.005 and P = 0.006, respectively), and increased in growth hormone-secreting adenomas (P = 0.003). In addition, expression of bax protein significantly decreased in recurrent tumors, in contrast to p53 protein, which showed a significant increase (P = 0.03 and P = 0.002, respectively).

Conclusions

We think that apoptosis-related proteins such as Bcl-2, Bax and p53 may be significantly related to hormone function and local control in pituitary adenomas.

Adrenocorticotropic Hormone Secreting Pituitary Adenomas: Analysis of Growth Fraction Using the MIB-1 Antibody

AIMS AND BACKGROUND

Pituitary adenomas are usually considered well differentiated tumors, even if in about one third of cases they invade surrounding tissues, with the possibility of postoperative relapse after complete surgical removal. Adrenocorticotropic hormone (ACTH) secreting adenomas seem to be the most infiltrating subtype, with a higher incidence of recurrence. Ki-67 is a nuclear antigen which is easily detectable by means of the MIB-1 monoclonal antibody, and the labeling index (LI) obtained can be considered a marker of tumor proliferation.

METHODS

In order to identify the growth fraction of these tumors we used the MIB-1 antibody to evaluate the expression of Ki-67 antibody in 11 ACTH secreting pituitary adenomas and to compare it with the LI obtained in 98 other hormone secreting or non-functioning pituitary adenomas consecutively operated on during a 40-month period.

RESULTS

In relation to surgically verified infiltration of the sellar floor dura and bone, we identified eight non-invasive and three invasive ACTH secreting pituitary adenomas. All invasive tumors infiltrated the wall of the cavernous sinus (CS). The mean Ki-67 LI was 5.88 +/- 9.13% versus 2.33 +/- 2.40% in non-ACTH secreting adenomas (P = 0.0025). It was 13.27 +/- 15.42% in invasive and 3.11 +/- 4.37% in non-invasive ACTH adenomas, and 18.40 +/- 17.82% in patients over 50 years versus 3.10 +/- 4.09% in younger subjects (P = 0.02).

CONCLUSIONS

Ki-67 LI is a useful marker in the determination of proliferative activity and invasiveness of anterior pituitary adenomas. Our data seem to confirm that ACTH secreting adenomas have a higher growth fraction than other pituitary adenomas and this observation presumably explains the higher incidence of relapse of these tumors even after macroscopically total removal.

Labeling index in pituitary adenomas evaluated by means of MIB-1: is there a prognostic role? A critical review

OBJECTIVE

The present article presents an overview of the literature, and analyses the methods and the primary questions related to assessment of proliferation index using the Ki-67/MIB-1 labeling index in pituitary adenomas. Although atypical adenomas are characterized by their atypical morphological features by an elevated mitotic index, a Ki-67 (MIB-1) labeling index greater than 3% and extensive nuclear staining for p53, use of the proliferation index (LI) of pituitary adenomas in assessing the degree of tumor aggressiveness is a controversial topic in the literature, and there are disparate results involving many studies.

METHODS

A review of literature was carried out to correlate the role of Ki-67 LI and its correlation with clinical findings, tumor size, invasiveness, recurrence, adenoma subtype, adenoma doubling time, and pituitary carcinomas is addressed.

RESULTS

The prognosis cannot be predicted on the basis of the Ki-67 LI alone. Although there is no direct relation between Ki-67 LI and some of these variables and controversial data were found regarding some topics, our review justify the use of Ki-67 in the analysis of pituitary adenomas as an additional information for clinical decision.

CONCLUSION

Although assessment of proliferative may be helpful in predicting subsequent tumor recurrence or invasiveness, there are many other important and as yet unidentified factors pituitary tumors. It is clear that further research is needed to clarify these molecular mechanisms to predict those with a potentially poor clinical outcome.

Expression of Ki-67, PCNA, and p27kip1 in canine pituitary corticotroph adenomas

Pituitary-dependent hypercortisolism (PDH), which is caused by adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas, is a common endocrinopathy in dogs. Dogs with non-enlarged pituitaries harboring a microadenoma have a better prognosis than those with enlarged pituitaries. The aim of this study was to investigate the expression of the proliferation markers Ki-67 and proliferating cell nuclear antigen (PCNA) and the cell-cycle inhibitor p27kip1 in corticotroph adenomas in enlarged and non-enlarged pituitaries. The expression of Ki-67, PCNA, and p27kip1 was analyzed by immunohistochemical staining of 17 pituitary adenoma samples harvested during pituitary surgery in dogs with PDH. The labeling index was calculated by counting the number of immunopositive cells per 1,000 cells. The mean (+/- standard deviation) labeling index for Ki-67 was 8.4%+/-14.2% for the group with enlarged pituitaries, and 8.8%+/-5.5% for the group with non-enlarged pituitaries; that for PCNA was 35.5%+/-12.2% and 37.0%+/-15.5%; and that for p27kip1 was 29.3%+/-22.6% and 42.5%+/-27.9%, respectively. No significant differences in Ki-67, PCNA, and p27kip1 labeling indices were found between enlarged and non-enlarged pituitaries. However, a trend toward significance was observed when comparing the expression of p27kip1 in enlarged pituitaries versus normal pituitary tissue. It is concluded that Ki-67 and PCNA are not useful as proliferative markers for studying the pathobiology of pituitary corticotroph adenomas in dogs.

The emerging role of pituitary tumor transforming gene in tumorigenesis

Pituitary tumor transforming gene (PTTG) is a newly discovered oncogene, and serves as a marker of malignancy grades in several forms of cancer, particularly endocrine malignancies such as pituitary adenomas. PTTG appears also to have a role in the genesis of some types of cancer. Also known as a human form of securin, PTTG is an anaphase inhibitor that prevents premature chromosome separation through inhibition of separase activity; hence, its degradation is required to start anaphase. Through this important function, PTTG participates in several key cellular events such as mitosis, cell cycle progression, DNA repair and apoptosis. The physiological importance of PTTG is indicated by the study of PTTG-null mice that have cell growth abnormalities in testis and pancreatic beta cells. Overexpression of PTTG has been observed in thyroid and colon cancers. In addition, 90% of pituitary adenomas overexpress PTTG, qualifying it as the best available marker for this disease. Although the exact mechanism is unknown, PTTG participates in the pathogenesis of various tumors, including pituitary tumors, by inducing aneuploidy and upregulating FGF-2, a potent mitogenic and angiogenic factor. Various growth factors, nuclear factors and hormones regulate PTTG expression in different tumor cells, which could be important to understand in order to obtain insight into the tumorigenic and tumor progression process. Here, we review the current knowledge of the biological and pathophysiological roles of PTTG.

Expression of p53, Ki-67 and c-erb B2 in growth hormone-and/or prolactin-secreting pituitary adenomas

The subcellular events implicated on the formation and behavior of pituitary adenomas are not fully understood. In this study we investigated the presence of p53, Ki-67 and c-erb B2 in 38 pituitary adenomas with immunohistochemical positivity for GH and prolactin (n=26; 68.4%), for prolactin (n=9; 23.7%) and for GH (n=3. 7.8%). The analyses revealed the following results: 24 (63.2%) tumors expressed variable positivity for c-erb B2, 11 (28.9%) expressed p53 positivity and 11 (28.9%) tumors were variably positive for Ki-67. Our results demonstrated a high percentage of GH/prolactin-, prolactin- and GH-secreting tumors with immunohistochemical positivity for c-erb B2. Once this membrane receptor is related to growth factors EGF and TGFalpha and both have a definite effect on tumor growth, our data suggest a possible role for c-erb B2 on the evolution of these tumors.

[Non-functioning pituitary adenomas: clinical features and immunohistochemistry]

Clinically non-functioning pituitary adenomas do not produce clinical signs of hormonal hypersecretion. Therefore, signs and symptoms will depend on the mass effect of these adenomas over the central nervous system. Their etiopathogeny is complex and their development is probably influenced by several factors, such as hypothalamic hormones (GHRH), growth factors (FGF), proliferation factors (PCNA, and KI-67), protein P53 and the proto-oncogene c-erb-B2.

OBJECTIVE

1) Determining the clinical features of a population of 117 patients treated for clinically non-functioning pituitary adenoma (age, sex, tumor size, number of surgical procedures, development of hormonal deficiency and hyperprolactinemia). 2) Identifying, after the patients had been clinically characterized, those with clinically non-functioning adenomas with positive immunohistochemistry for hypophyseal hormones (PRL, LH, FSH, GH, TSH and ACTH). 3) Determining if the immunohistochemistry of this population was positive for the cellular proliferation factor Ki-67, protein P53 and protein C-erb-B2 and establishing a correlation with tumor size and tumor invasiveness. This will help in the evaluation of the prognostic value of these proliferation factors. 4) Confronting the results of immunohistochemistry using a standard block with the results of immunohistochemistry using a tissue micro-array.

METHOD

Study of the clinical features of 117 patients with clinically non-functioning pituitary adenoma (age, sex, tumor size, number of surgical procedures, development of hormonal deficiency and hyperprolactinemia). Immunohistochemical study (H&E) of 39 patients for hypophyseal hormones, protein P53, protein C-erb-B2, Ki-67 to establish their correlation to tumor growth. The next step was a tissue micro-array of the 39 previously studied cases, using immunohistochemistry for hypophyseal hormones, protein P 53, protein C-erb-B2, Ki-67 to establish their correlation to tumor growth.

RESULTS

There was no statistically significant difference between males and females with regards to age, tumor size and number of surgical procedures (p=0.279, p=813, p=139 respectively). There is a statistically significant correlation between the size of the tumor, the number of surgical procedures and hormonal deficiency (p=0.032, p=0.223 respectively). There was no statistically significant correlation between a positive immunohistochemistry for protein P53, protein C-erb-B2, Ki-67 and tumor size (r=0.182, p=0.396; r=-0.181, p=0.397; r=0.272, p=0.199, respectively). The tissue micro-array also did not demonstrate a correlation between positive immunohistochemistry for Ki-67 and C-erb-B2 and tumor size, but it showed a statistically significant correlation between a positive immunohistochemistry for p53 and tumor size (r=-0.696; p=001).

CONCLUSION

The biological behavior of the clinically non-functioning adenoma is similar for both sexes. The larger the tumor the greater the number of surgical procedures needed. Hormonal deficiency also becomes more significant as the size of the tumor increases. This paper suggests that a positive immunohistochemistry for p53 is negatively correlated to tumor size, thus demonstrating that it has a predictor value. However, a positive immunohistochemistry for Ki-67 and protein C-erb-B2 does not seem to be a prognostic factor for clinically non-functioning pituitary adenomas, as is the case with other neoplasias.

Relevance of high Ki-67 in pituitary adenomas

Pituitary adenomas are heterogeneous in growth rate, invasiveness, and recurrence. To understand the biological behavior of the individual adenoma more fully, cell proliferation markers such as monoclonal antibodies targeted against the Ki-67 antigen have been applied. The Ki-67 antigen is a protein related to cell proliferation and is expressed in cell nuclei throughout the entire cell cycle. The authors report the case of an extremely rapidly growing pituitary adenoma with cavernous sinus invasion. The lesion, which displayed a high Ki-67 labeling index (LI; 22%), was found in a 54-year-old woman who presented with diplopia and headaches. The patient underwent three transsphenoidal operations in less than 6 months and, ultimately, was treated with fractionated intensity-modulated radiation therapy. The relationships between high Ki-67 LIs and tumor recurrence, invasiveness, and growth velocity in pituitary adenomas are reviewed.

Measurement of Ki-67 antigen in 159 pituitary adenomas using the MIB-1 monoclonal antibody

Pituitary adenomas sometimes show rapid growth and recurrence, and about one third invade the structures surrounding the sella turcica. In an attempt to determine aggressive behavior at an early stage, we used the MIB-1 antibody to identify the Ki-67 antigen. The present study was designed to evaluate pituitary adenomatous tissue in terms of secretion and proliferation and to correlate the Ki-67 index with hormone phenotype and invasive behavior. Material from 159 patients submitted to one or more resections of pituitary adenomas was evaluated. Forty-two non-secretory adenomas and 43 adenomas immunoreactive for growth hormone, 19 for prolactin, 18 for growth hormone and prolactin, 16 for adrenocorticotropic hormone (ACTH), and 21 cases of plurihormonal/gonadotropin adenomas were detected by immunohistochemistry. The MIB-1 antibody was positive in 139 samples and the Ki-67 index ranged from 0.16 to 15.48% (mean = 1.22 +/- 2.09%), with no significant difference between genders, age groups, or secretory and non-secretory status. The Ki-67 index was higher in ACTH-secreting adenomas. Invasive pituitary adenomas had a significantly higher Ki-67 index (2.01 +/- 3.15%) than macroadenomas with or without supra-sellar extension (1.12 +/- 1.87%; P = 0.02). The index was not significantly different in the subgroup of adenomas with invasion of the cavernous sinus compared to groups with other types of invasion. We conclude that tumoral proliferative activity evaluated by the detection of the Ki-67 antigen is significantly higher in invasive than noninvasive adenomas, information which can be useful in therapeutic postoperative management since index cut-off values associated with aggressive behavior can be established.

Expression of Ki-67 antigen in nonfunctioning pituitary adenomas: correlation with growth velocity and invasiveness

Object. The cell cycle—dependent nuclear antigen Ki-67 is related to growth potential in a variety of tumors. Elevated expression of Ki-67 was previously shown in recurrent pituitary adenomas; however, it has remained unclear whether this expression is related to the growth velocity or invasive behavior of these tumors. The aim of this study was to determine the correlation of Ki-67 antigen expression, growth velocity, and invasiveness in nonfunctioning pituitary adenomas.

Methods. Between April 1998 and April 2002, 23 patients with nonfunctioning pituitary adenomas who had participated in an observation period in which multiple computerized tomography and magnetic resonance imaging studies had been performed were surgically treated in our department. Tumor volumes were assessed using a stereological method based on the Cavalieri principle. The growth rate was calculated for each patient. Expression of Ki-67 antigen was examined using the monoclonal antibody MIB-1.

The assessed growth velocity of the adenomas was best described by a linear growth model. The correlation between Ki-67 expression and growth rate was highly significant. Rapidly growing adenomas (>0.07% daily increase in size) were found to have a Ki-67 labeling index (LI) exceeding 1.5%, whereas all five adenomas with a very slow growth rate (< 0.02% daily increase in size) had a Ki-67 LI lower than 1.5%. No correlation was found between the growth rate and the invasive character of the adenomas.

Conclusions. Expression of Ki-67 antigen is significantly correlated to the growth velocity of pituitary adenomas. Invasive behavior is a feature independent of proliferative activity. The extent of Ki-67 expression is helpful for clinical decision making and routine assessment of Ki-67 is recommended during the histopathological workup of pituitary adenomas.

Significance of leptin expression in invasive potential of pituitary adenomas

We immunohistochemically examined the expression of leptin in pituitary adenomas to investigate the correlation between the invasiveness of tumours and leptin expression. The subjects consisted of 79 patients with pituitary adenoma and were classified into the following groups: (1) non-functioning adenomas; (2) GH-secreting adenomas; (3) prolactinomas; (4) ACTH-secreting adenomas; (5) others (LH, FSH or TSH-secreting adenomas). Thereafter all cases were subdivided according to the size of tumour and the presence of invasion to the surrounding tissue. Among non-functioning adenomas, there was no significant difference between invasive and non-invasive non-functioning adenoma. In functioning adenomas, a significant difference in leptin expression was noted in intrasellar non-invasive adenomas compared to other adenomas. There was also a significant difference in leptin expression between non-invasive and invasive adenomas regardless of size. These results suggest that leptin has a role in the invasive potential of functioning adenomas.

Expression of pituitary tumour transforming gene (PTTG) and fibroblast growth factor-2 (FGF-2) in human pituitary adenomas: relationships to clinical tumour behaviour

OBJECTIVE

Pituitary tumour transforming gene (PTTG) encodes a multifunctional protein that is implicated in initiating and perpetuating pituitary adenoma growth. PTTG appears to have key regulatory functions in determining control of many fundamental cellular events including mitosis, cell transformation, DNA repair and gene regulation. Several of these events are mediated through interactions with PTTG binding factor (PBF) and fibroblast growth factor-2 (FGF-2). Given this background, we have determined the expression of PTTG, PBF, FGF-2 and its receptor FGF-R-1 in a large cohort of pituitary adenomas and have sought associations between levels of gene expression and clinical markers of tumour behaviour.

PATIENTS AND METHODS

We used real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analyses to measure PTTG, PBF, FGF-2 and FGF-R-1 expression in ex vivo pituitary tumours (N = 121). Clinical data, including accurate radiological assessment of tumour characteristics, were used to determine any associations between gene expression and tumour behaviour.

RESULTS

PTTG was increased significantly (fivefold, P = 0.005) in adenomas compared with normal pituitaries. We also demonstrated that PBF was similarly raised in adenomas (sixfold, P = 0.0001), and was significantly correlated with PTTG expression. FGF-2 and its receptor FGF-R-1 were also raised in adenomas compared with normal pituitary tissue. Moreover, significantly enhanced expression of FGF-R-1 was observed in invasive adenomas compared with other pituitary tumours.

CONCLUSIONS

Our data support a fundamental role for PTTG-mediated upregulation of FGF-2 signalling in pituitary tumorigenesis and growth, and suggest that receptor-mediated mechanisms of growth factor action may be critically important. Further prospective studies are required to determine whether measurement of FGF-R-1 mRNA will be of clinical use as a prognostic marker in patients with pituitary adenomas.

Subcellular localization of basic fibroblast growth factor and fibroblast growth factor receptor 1 in pituitary adenomas

The aim of this study was to assess the subcellular localization of basic fibroblast growth factor (bFGF) and fibroblast growth factor receptor 1 (FGFR1) in pituitary adenomas. We studied 61 patients who had primary pituitary adenomas and underwent operation. The immunohistochemistry for bFGF, FGFR1, and MIB-1 was examined in paraffin-embedded tissues. The bFGF immunoreactivity in the nucleus was recorded as the bFGF nuclear index, which was calculated as the percentage of tumor cells with the bFGF immunoreactivity in the nuclei when more than 1000 tumor cells were examined. Recurrent adenomas were found in 7 patients during follow-up periods ranging from 8 to 134 months (mean, 57.2). The recurrent adenomas had significantly larger mean bFGF nuclear indices (74.8 +/- 28.8%) than the nonrecurrent adenomas (25.4 +/- 32.1%, P = 0.0003). The bFGF nuclear index also correlated significantly with the maximum tumor diameters and the invasiveness to the cavernous sinuses (Knosp grade) in the adenomas. The cytoplasmic FGFR1 immunoreactivity was inversely correlated (P < 0.02) with maximum tumor diameter. Neither cytoplasmic bFGF, cytoplasmic FGFR1, nor MIB-1 staining index showed any relationship with the recurrence of pituitary adenomas. These findings suggest that the nuclear accumulation of bFGF plays an important role in the progression of pituitary adenomas without its receptors.

Expression of p53 protein in pituitary adenomas

Inactivating mutations of TP53, a tumor suppressor gene, are associated with abnormal cell proliferation. Although p53 expression is common in many human malignancies, p53 protein has seldom been evaluated in pituitary tumors. When detected, the percentage of p53-positive cells is low, and, in general, it is exclusive for invasive lesions. The aim of the present study was to use immunohistochemistry to determine the presence of p53 protein in pituitary adenomas from tumor samples of 163 surgeries performed in 148 patients (40% male, 60% female). In 35% of the cases the adenoma was nonfunctional, while in the others it was associated with PRL, GH and/or ACTH endocrine hypersecretion syndrome. Macroadenomas were observed in 83.2% of the cases with available neuroimage evaluation, of which 28% invaded the cavernous, sphenoid and/or ethmoidal sinus, bone, third ventricle or subfrontal lobe. p53 protein was detected in 2/148 patients (1.3%). Immunohistochemistry was positive for PRL and GH in these cases. Due to the high percentage of invasive pituitary adenomas found in our study, the low frequency of p53 detection suggests that it is inadequate as a routine marker for aggressiveness and as a predictive factor of tumor behavior.

Nuclear accumulation of basic fibroblast growth factor as a predictor for the recurrence of pituitary adenomas

Although pituitary adenomas often recur, a reliable predictor for their recurrences has not yet been established. The aim of this study is to assess the utility of the nuclear accumulation of basic fibroblast growth factor (bFGF) as a predictor for the recurrence of pituitary adenomas. We studied 64 patients who had primary pituitary adenomas and underwent operations. The immunohistochemistry for bFGF and MIB-1 was retrospectively examined in paraffin-embedded tissues. The bFGF immunoreactivity in the cytoplasm was assigned one of four grades and the bFGF immunoreactivity in the nucleus was recorded as the bFGF nuclear index (NI), which was calculated as a percentage of tumor cells with the bFGF immunoreactivity in the nuclei in more than 1000 tumor cells. Recurrent adenomas were found in 7 patients during follow-up periods ranging from 8 to 134 months (mean: 57.3). Kaplan-Meier analysis demonstrated that high bFGF NI (>30%) correlated with poor recurrence free rate (p < 0.02). We assessed the relative contribution of bFGF NI to recurrence free by using multivariate (Cox's proportional hazards model) analyses with variable factors. Multivariate analysis showed that only bFGF NI was a potential predictor of recurrence free, independent of all other variables. High bFGF NI (>30%) had a relative risk of 8.9, with a 95% confidence interval of 1.0-74.9 (p < 0.05). We suggest that the bFGF NI may be a potentially useful predictor for the recurrence of pituitary adenomas.

Anterior pituitary adenomas in patients aged more than 65 years: analysis of growth fraction (using the MIB-1 monoclonal antibody) and of clinical features in comparison to younger patients

AIMS AND BACKGROUND

The incidence of pituitary adenomas (PA). in patients aged more than 65 years is relatively low. The goal of this study was to evaluate the growth fraction and the clinical features of PA affecting old patients and to compare the results to those of younger subjects.

METHODS

We evaluated the Ki-67 LI using the monoclonal antibody MIB-1 in 21 patients of more than 65 years of age affected by PA consecutively operated on and compared the mean LI with that one of 104 patients under 65 operated on in the same period. The clinical behavior of PA was also analyzed in both groups.

RESULTS

In older cases PA occurred more frequently with visual disturbances: 17 out of 21 (80.9%) older patients showed pre-operative visual disturbances, versus 43 out of 104 (41.3%) younger patients (P=0.0009). Fifteen out of 21 (71.4%) older patients had a non-functioning PA, versus 38 out of 66 (36.5%) younger patients (P=0.003). In relation to surgically verified infiltration of sellar floor dura and bone, we identified non-invasive (12/21 older cases) and invasive (9 cases) adenomas; the wall of the cavernous sinus was infiltrated in 5 cases. The overall mean Ki-67 LI was 4.06+/-6.73 versus 2.35+/-2.54% of younger patients (P=0.04).

CONCLUSIONS

Our data confirm that Ki-67 LI detected by the MIB-1 monoclonal antibody is a useful marker in the determination of the growth fraction of PA. In relation to our preliminary results, PA in the elderly seem to have a higher growth fraction than in younger patients, are more often non-functioning and occur frequently with visual disturbances. In order to confirm our data further larger studies are necessary.

Lack of correlation between Ki-67 labelling index and tumor size of anterior pituitary adenomas

AIMS AND BACKGROUND

The Ki-67 is a nuclear antigen detected by the monoclonal antibody MIB-1 and its Labeling Index (LI) is considered a marker of normal and abnormal cell proliferation. Pituitary adenomas are generally well differentiated neoplasms, even if in about one third of cases they are invasive of surrounding tissues. The aim of this study is to evaluate the correlation between Ki-67 labelling index and tumor size of pituitary adenomas extimated by means CT and MRI and confirmed at operation.

METHODS

Using the monoclonal antibody MIB-1, we evaluated the expression of Ki-67 in 121 anterior pituitary adenomas consecutively operated on in a 48-month period.

RESULTS

In relation to neuroradiological (CT and MRI) and surgically verified tumor size, we identified 24 microadenomas, 27 intrasellar macroadenomas, 34 intra-suprasellar macroadenomas, and 36 intra-supra-parasellar macroadenomas. The adenomas were non-infiltrating (76 cases) and infiltrating (45 cases) adenomas. The wall of the cavernous sinus (CS) was infiltrated in 18 cases. Forty-eight adenomas were non-functioning and 73 functioning. The overall mean +/- SD Ki-67 LI was 2.72 +/- 2.49% (median 1.6). It was 2.59 +/- 1.81 in microadenomas, 2.63 +/- 3.45 in intrasellar macroadenomas, 1.91 +/- 2.11 in intra-suprasellar macroadenomas, and 3.29 +/- 5.45 in intra-supra-parasellar macroadenomas (p = 0.27). It was 3.73 +/- 5.13% in infiltrating and 2.03 +/- 2.41% in non-infiltrating adenomas (p = 0.02), and 5.61 +/- 7.19% in CS-infiltrating versus 2.09 +/- 2.37% in CS-non-infiltrating adenomas (p = 0.0005).

CONCLUSIONS

Our preliminary results seem to exclude significative correlations between Ki-67 LI and tumor size of anterior pituitary adenomas, even if this index can be considered a useful marker in the determination of the infiltrative behaviour of these tumors.

Relationships among DNA Index, S-Phase, and invasive behavior in anterior pituitary adenomas. A cytometric study of 61 cases with Feulgen-positive DNA analysis

BACKGROUND

Pituitary adenomas are usually well differentiated neoplasms, although in about 1/3 of cases they invade the surrounding dura mater and bone, as confirmed by surgical findings, resulting in a long-term possibility of relapse.

METHODS

To identify the cellular growth rate and to correlate it with surgical evidence of invasiveness, we performed the analysis of DNA with static cytometric quantitation on fresh surgical specimens, using a computer-assisted image processor. The DNA index and the percentage of cells in S-phase (%SPh) were obtained in 61 pituitary tumors consecutively operated on. In relation to surgically verified infiltration of dura and bone, we identified 39 noninvasive and 22 invasive adenomas. The cavernous sinus (CS) was infiltrated in 13 cases. On the basis of immunohistochemical staining and endocrine activity we recognized 27 nonsecreting and 34 secreting adenomas.

RESULTS

The DNA content was aneuploid in 33 cases (11 nonfunctioning, 22 functioning; p = 0.05); there was no correlation with the invasive behavior of the adenomas. The DNA index ranged between 0.93 and 2.50 (median 1.13); the range of %SPh was 0-12.00% (median 2.54%). In invasive adenomas the mean DNA index was 1.33 (p not significant) and the mean %SPh was 4.03% (p = 0.05). In CS-infiltrating pituitary adenomas, the mean DNA index was 1.44 (p = 0.04) and the mean %SPh was 4.52% (p = 0.05).

CONCLUSIONS

Our preliminary results seem to reveal a correlation between DNA index, %SPh, and invasive behavior of pituitary adenomas, encouraging the use of DNA analysis in the prognostic evaluation of these tumors.

Proliferation Index of Nonfunctioning Pituitary Adenomas: Correlations with Clinical Characteristics and Long-term Follow-up Results

OBJECTIVE

The recurrence of nonfunctioning pituitary adenomas (NFPAs) after surgical removal is common. The aim of our study was to investigate and correlate the growth fraction of NFPAs with clinical characteristics and long-term follow-up results.

METHODS

Tumor specimens were obtained from 101 consecutive patients with NFPAs (48 female patients and 53 male patients; mean age, 52.0 ± 1.5 yr). Specimens were immediately fixed in 10% buffered formalin and then embedded in paraffin. The Ki-67 antigen was assessed by immunocytochemical analysis using the monoclonal antibody MIB-1. The Ki-67 antigen labeling index (LI) was determined by counting a total of at least 1000 neoplastic nuclei.

RESULTS

The mean Ki-67 LI for the 101 patients was 2.4 ± 0.3% (range, 0–23.0%). Only age at surgery was inversely correlated with the Ki-67 LI; sex, maximal tumor diameter, and invasiveness into the cavernous sinuses did not significantly affect the Ki-67 LI. The mean follow-up period was 39.7 ± 2.1 months. During follow-up monitoring, 23 patients experienced tumor recurrence, after a mean period of 28.6 ± 4.8 months. Invasiveness of the tumor on preoperative magnetic resonance imaging scans was the strongest predictor of late tumor recurrence, followed by previous pituitary surgery, younger age, and lack of postoperative radiotherapy. The Ki-67 LI had no independent prognostic value.

CONCLUSION

Our study suggests that the clinical characteristics of patients with NFPAs, except for age at surgery, are not correlated with the Ki-67 LI. Moreover, the Ki-67 LI does not seem to provide independent information to identify patients at high risk for tumor recurrence.

Adenomas hipofisários: relação entre invasividade e índice proliferativo tumoral

Analisamos 76 pacientes com adenomas hipofisários do ponto de vista clínico, radiológico e tratamento cirúrgico. Todos os casos foram estudados por imuno-histoquímica e em 49 pacientes foi pesquisado o anticorpo monoclonal PCNA. Os adenomas bi-hormonais foram os mais frequentes seguidos dos prolactinomas e os adenomas não secretantes. Os adenomas bi-hormonais não secretantes e os produtores de subunidade alfa foram proporcionalmente mais invasivos pelos critérios radiológicos. A maioria dos pacientes (59) foi operada por via transeptoesfenoidal, em seis casos a via transcraniana foi realizada e em 11 pacientes houve necessidade das duas abordagens. A ressecção foi total em 32 pacientes, a maioria em microadenomas, subtotal em 15 e parcial em 29. A complicação endócrina mais frequente foi diabetes insipidus. Houve tendência de associação positiva para os adenomas secretantes e PCNA mais elevado, assim como relação positiva quando analisamos os adenomas invasivos pela tomografia computadorizada ou ressonância magnética e o PCNA 3 e 4. A melhora visual foi observada em 85% dos macroadenomas, mesmo quando a ressecção foi parcial ou subtotal.

Calcitonin inhibits anterior pituitary cell proliferation in the adult female rats

Previous studies have shown that CT-like immunoreactive peptide(s) (pit-CT) is synthesized by the anterior pituitary (AP) gland, and exogenously added salmon(s) CT inhibits PRL release and PRL gene transcription in cultured AP cells. Anti-sCT serum, which immunoreacts with pit-CT, stimulates PRL secretion, suggesting pit-CT is a physiologically relevant PRL-inhibiting hormone. Using proliferating cell nuclear antigen (PCNA) staining and 5-bromo-2'deoxyuridine (BrdU) incorporation into newly replicated DNA, the effect of calcitonin (CT) on cellular proliferation in the rat anterior pituitary gland (AP) was examined. CT significantly attenuated PCNA-immunopositive as well as BrdU-positive AP cell populations in dispersed rat AP cells. A second series of experiments tested the effects of CT on AP cell proliferation in vivo. OVX + E2 rats were injected with 200 microg CT (iv), the rats killed at various time points, and the APs were processed for BrdU staining. CT inhibited BrdU incorporation at all time points up to 15 h after the injection, and this inhibitory effect was reversed at later time points. The effect of CT was concentration dependent, and a maximal inhibition was observed 10 h after the CT injection. Subsequent experiments identified CT-responsive AP cell populations using double immunofluorescence for BrdU and either PRL or FSH. The number of BrdU-labeled lactotropes in the AP gland declined by 74% in the CT-treated rats. Neutralization of endogenous pit-CT by passive immunization with anti-sCT serum caused a 2-fold increase in AP cell proliferation. These results suggest an important role for the endogenous pit-CT in regulation of lactotrope population of the AP gland.

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.

Ki-67 labelling index and invasiveness among anterior pituitary adenomas: analysis of 103 cases using the MIB-1 monoclonal antibody

AIMS

To investigate the relation between proliferative activity of anterior pituitary adenomas, quantified by the Ki-67 labelling index, and their invasive behaviour.

METHODS

Expression of Ki-67 was evaluated in 103 anterior pituitary adenomas consecutively operated on in a 36 month period and correlated with surgical evidence of invasiveness.

RESULTS

Non-invasive (n = 65) and invasive (n = 38) adenomas were identified from surgically verified infiltration of sellar floor dura and bone. The wall of the cavernous sinus was infiltrated in 16 cases. Forty one adenomas were non-functioning and 62 functioning (24 prolactin, 21 growth hormone, 10 ACTH, seven mixed). The overall mean (SD) Ki-67 labelling index was 2.64 (3.69) per cent (median 1.5). The mean index was 3.08 (4.59) per cent in functioning and 1.97 (1.78) per cent in non-functioning tumours; 5.47 (9.52) per cent in ACTH adenomas and 2.33 (2.42) per cent in others (p = 0.01); 3.71 (5.17) per cent in invasive and 2.01 (2.45) per cent in non-invasive adenomas (p = 0.027); and 5.58 (7.24) per cent in cavernous sinus infiltrating v 2.10 (2.39) per cent in cavernous sinus non-infiltrating adenomas (p = 0.0005). To identify a value of labelling index beyond which adenomas should be considered invasive and another beyond which cavernous sinus infiltration should be suspected, normality Q-Q plots were obtained: a threshold labelling index of 3.5% for invasive adenomas and of 5% for cavernous sinus infiltrating adenomas was defined, with statistically significant differences (p = 0.02 and p = 0.004, respectively).

CONCLUSIONS

The Ki-67 labelling index can be considered a useful marker in determining the invasive behaviour of anterior pituitary adenomas.

Adrenocorticotropin-Producing Pituitary Carcinoma with Expression of c-erbB-2 and High PCNA Index: A Comparative Study with Pituitary Adenomas and Normal Pituitary Tissues

Pituitary carcinomas are very rare neoplasms with a poor prognosis. We report a case of Cushing's disease resulting from a pituitary carcinoma in a 22-yr old female, who died of massive hepatic failure. At autopsy, there was invasion of the parasellar structures and vasculature by the tumor, which stained positively only for ACTH. There were two metastatic nodules in the liver, which also stained positively for ACTH. When compared to other cases of Cushing's disease (n = 52), other pituitary adenomas (n = 292). and normal pituitary tissues (n = 21), the pituitary carcinoma was the only one with c-erbB-2 membrane staining in both the sellar-located tissue and liver metastasis. C-erbB-2 staining was present in the cytoplasm of a variable number of cells in 40% of the invasive adenomas (n = 103), while only 1.2% of the noninvasive tumors (n = 241) expressed this protein (p < 0.001). No particular immunohistological type preferentially expressed this protein. In normal pituitary tissues, 10% of the cells expressed cytoplasmic c-erbB-2. A higher index of proliferating cell nuclear antigen (PCNA) in the primary tumor and liver metastasis (10%) was also found compared to other ACTH-secreting adenomas (invasive, 3.4 -t 1 S% vs 1 ii +/- 1.5% in noninvasive) and other pituitary tumors (invasive, 2.9 +/- 1.5% vs 1.5 +/- 1.3% in noninvasive). The PCNA index was significantly higher in invasive tumors than in noninvasive adenomas (p = 0.004). PCNA staining was negative in normal pituitary tissues. Staining for p53, pRB and p(2ras) was negative in the carcinoma and liver metastasis. We suggest that the c-erbB-2 membrane pattern and a higher PCNA index may indicate a worse prognosis in adenohypophyseal neoplasia.