DNA replication regulation protein Mcm7 as a marker of proliferation in prostate cancer

BACKGROUND: Recent studies have shown that minichromosome maintenance (MCM) proteins (Mcm2-7) may be useful proliferation markers in dysplasia and cancer in various tissues. AIMS: To investigate the use of Mcm7 as a proliferation marker in 79 lymph node negative prostate cancers and compare it with Ki-67, a commonly used cell proliferation marker. METHODS: The percentage of proliferating cells (proliferation index; PI) was calculated for basal and luminal epithelial cells in benign prostate tissue, prostatic intraepithelial neoplasia (PIN), and epithelial cells in adenocarcinoma. The PI for each biomarker was correlated with the preoperative prostate specific antigen concentration, the Gleason score, surgical resection margin status, and the AJCC pT stage for each patient. RESULTS: The mean PIs for Ki-67 and Mcm7 were: benign luminal epithelium 0.7 and 1.2 and benign basal epithelium 0.8 and 8.2; PIN non-basal epithelium 4.9 and 10.6 and PIN basal epithelium 0.7 and 3.1; adenocarcinoma 9.8 and 22.7, respectively. Mcm7 had a significantly higher mean PI (p<0.0001) than Ki-67 for all cell categories except benign luminal epithelial cells. Mcm7 was a better discriminatory marker of proliferation between benign epithelium, PIN, and invasive adenocarcinoma (p<0.0001) than Ki-67. The drop in Mcm7 mean basal cell PI from benign epithelium to PIN epithelium was significantly larger than for Ki-67 (p<0.0001). Mcm7 had a significantly higher PI than Ki-67 at each risk level. CONCLUSION: Mcm7 may be a useful proliferation marker in prostatic neoplasia and warrants further evaluation as a complementary tool in the diagnosis of PIN and prostate carcinoma.     

Proliferative activity determined by DNA flow cytometry and proliferating cell nuclear antigen (PCNA) immunohistochemistry as a prognostic factor in prostatic carcinoma.

Proliferative activity was measured in 165 paraffin-embedded prostatic carcinomas using DNA flow cytometric analysis of the S-phase (SPF) and G2/M-phase fractions and CAS 200 image analysis of the proliferating cell nuclear antigen (PCNA) expression defined immunohistochemically by PC10 and 19A2 monoclonal antibodies. No significant associations were found between the flow cytometric and the two immunohistochemical measures of cell proliferation. Of the four indices, only SPF, S + G2/M, and immunostaining with 19A2 antibody were associated with the poor histological grade of the tumour. High SPF and S + G2/M were significantly associated with poor 10-year overall survival (P < 0.001) and prostatic carcinoma-specific survival (P < 0.01). Multivariate analyses of prostatic carcinoma-specific survival in patients with non-metastatic disease (M0-stage) indicated that only S + G2/M, T-stage, and histological grade (only if re-evaluated by a single pathologist) had independent prognostic significance. High-level PCNA staining (> 16 per cent of cells stained) with 19A2 antibody was associated with poor prognosis only in univariate analysis, and PC10 immunostaining had no prognostic value. In conclusion, a high proliferative activity as defined by flow cytometric S+G2/M is an independent predictor of poor survival in patients with non-metastatic prostatic carcinoma. PCNA immunostaining from formalin-fixed, paraffin-embedded prostatic carcinomas has little, if any, prognostic value.     

Limiting the diagnosis of atypical small glandular proliferations in needle biopsies of the prostate by the use of immunohistochemistry

Prostatic biopsies containing small glandular formations suspicious of, but not diagnostic for, carcinoma represent a diagnostic dilemma, as they cannot be definitely identified as either benign or malignant. The term 'atypical small acinar proliferation' (ASAP) in the differential diagnosis of carcinoma has recently evoked considerable discussion. This study has tried to assess the biological potential of ASAP by further immunohistochemical (IHC) analysis. Biopsy-proven cases of ASAP (n=114) were analysed, in which consecutive sections still contained the suspicious lesion. IHC studies were undertaken with anti-cytokeratin 34betaE12 and the proliferation marker MIB-1. Staining with 34betaE12 revealed a complete basal cell layer in 25 cases (21.9%), a fragmented layer in 58 cases (50.9%), and absence of basal cells in 31 cases (27.2%). MIB-1 labelling indices (LIs) in these three groups were significantly higher than in benign prostatic tissue (p<0.001) and reached the level of low-grade prostatic carcinoma (p>0.05). The suspicious morphology of ASAP on haematoxylin and eosin-stained slides was supported by the finding of elevated proliferative activity. Subgroups were revealed by immunohistochemical assessment of basal cell status and cases without basal cells were diagnosed as carcinoma. Nevertheless, rebiopsy is recommended if radical surgery is planned, to exclude insignificant cancer. Cases with a complete or fragmented basal cell layer were regarded as non-malignant. Whether a fragmented basal cell layer reflects a technical artefact or transition to carcinoma is unknown, but the proliferative activity of both lesions was increased and corresponded to that of low-grade prostatic carcinoma. In these cases, therefore, at least clinical follow-up is strongly recommended and repeat biopsies are encouraged.     

POSITIVE CORRELATION BETWEEN APOPTOTIC AND PROLIFERATIVE INDICES IN GASTROINTESTINAL LYMPHOMAS OF MUCOSA-ASSOCIATED LYMPHOID TISSUE (MALT)

To understand the role of deregulation of apoptosis in the pathogenesis of gastrointestinal MALT lymphoma, apoptosis has been quantitatively studied in paraffin sections from 40 cases (19 low grade, 21 high grade). The extent of apoptosis was correlated with histological grade, proliferative activity as measured by immunostaining of Ki67 proliferation antigen, and the expression of bcl-2 and p53 oncoproteins, which are known to participate in the regulation of apoptosis. Both apoptotic and proliferative indices were significantly ( P <0·00001) higher in high-grade than in low-grade tumours. Overall, apoptotic indices were negatively correlated with bcl-2 expression, particularly in low-grade tumours in which both strong bcl-2 expression and low levels of apoptosis were observed. Thus, the slow expansion of low-grade MALT lymphoma may partly result from a prolonged life-span of tumour cells, due to bcl-2-mediated blockage of apoptosis. No difference in apoptotic indices was found between p53-positive and p53-negative cases. Furthermore, correlation analysis revealed a significantly positive association between apoptotic and proliferative indices. This supports the current belief that the mechanisms controlling apoptosis and proliferation are both activated during the cell cycle and whether a cell enters the proliferation cycle or the apoptotic process depends on survival factors.     

Metallothionein isoform II expression in hyperplastic, dysplastic and neoplastic prostatic lesions

BACKGROUND: Metallothionein is a low-molecular-weight cysteine-rich protein that has the ability to bind and sequestrate heavy metal ions. It is associated with metalloregulatory functions such as cell proliferation, growth and differentiation. AIMS: To investigate the expression of metallothionein in hyperplastic, dysplastic and neoplastic prostatic lesions and to correlate its expression with histological grade of prostatic carcinoma. Method: The study was carried out on formalin-fixed and paraffin-wax-embedded tissue blocks from 8 patients with benign prostatic hyperplasia, 6 patients with prostatic intraepithelial neoplasia (PIN) and 30 patients with prostatic carcinoma, using the streptavidin-biotin technique. The histological grade was defined and the carcinomas were divided into low-grade (Gleason Score 2-4), 12 moderate grade (Gleason Score 5-6) and 10 high-grade (Gleason Score 7-10) carcinomas. RESULTS: Patchy metallothionein staining of epithelial cells was observed in normal and benign prostatic tissues. All cases of PIN and 20 of 30 patients with prostatic carcinoma showed positive staining for metallothionein. Metallothionein expression considerably increased from low-grade to high-grade tumours. The proportion of cells staining positively for metallothionein was directly correlated with histological grade of prostatic carcinoma. The epithelial cells lack uniformity in staining intensity, but the percentage of strongly positive cells increased with the histological grade of prostatic carcinoma. CONCLUSIONS: The high incidence of metallothionein expression in PIN in our study suggests that it is associated with early prostate tumorigenesis. Also, metallothionein expression was directly correlated with the histological grade of prostatic carcinoma, suggesting that metallothionein may be a useful marker for predicting the prognosis of prostate cancer.     

Role of cytologic criteria in the histologic diagnosis of Gleason grade 1 prostatic adenocarcinoma

Gleason grade 1 prostatic adenocarcinoma is defined by its gland architecture, which resembles that of benign prostate more than any other grade. It is characterized by closely spaced glands and expansile tumor border. Cytoplasm is clear to pale, superficially identical to benign nodular hyperplasia (BPH). However, there is recent evidence that prostatic "clear-cell carcinoma," including grade 1, has cytoplasm whose composition is distinctively different from BPH, being filled with lipid rather than with the protein-rich granules that characterize benign secretory cells or the nongranular protein matrix of other prostate cancers. We reasoned that grade 1 cancer might also have additional distinctive cellular features; we tested this hypothesis by observations on 17 grade 1 carcinoma foci found as components of transition zone clear-cell cancers. Unlike BPH secretory cells, cells of grade 1 cancer were uniformly large with even, straight borders laterally and luminally. Nuclei appeared sometimes benign but were fixed in a basal row dissimilar to the uneven distribution in BPH. Nuclear pyknotic foci, blue-tinged cytoplasm, and abundant dense luminal secretion were distinctively common. Immunostain for glutathione-S transferase was negative in grade 1 cancer but lightly positive in BPH secretory cells. These cytologic findings were proposed to be useful as diagnostic clues, especially in small-needle biopsy samples, in which architecture may be difficult to interpret. HUM PATHOL 32:441-446.     

Ki-67 expression in early prostate cancer and associated pathological lesions.

AIM: To assess cell proliferation in early prostate cancer and associated pathological lesions. METHODS: Using the Ki-67 antibody, the cell proliferation index was measured in early stage prostatic carcinoma in 37 incidental tumours diagnosed at transurethral prostatectomy (TURP) and in 20 low volume cancers treated by radical prostatectomy. Proliferation indexes have also been measured in areas of normal peripheral zone, transition zone hyperplasia, atrophic appearing lobules, and high grade prostatic intraepithelial neoplasia in the radical prostatectomy cases. RESULTS: In the TURP series the proliferation index correlated with grade and stage. Logistic regression analysis, however, showed that Gleason grade was the most reliable predictor of biopsy proven residual disease and clinical progression. In the radical series transition zone carcinoma the proliferation index was half that of peripheral zone carcinoma. The atrophic lobules also showed a high proliferation index of the same order as seen in the peripheral zone carcinoma. Normal peripheral zone showed the lowest proliferation index and in hyperplastic transition zone it was also less than the other areas. CONCLUSIONS: There is only limited support for the correlation of proliferation index with grade in early stage prostatic carcinoma. The findings do not suggest that proliferation index adds to the prognostic information given by grade and stage in pT1 disease. The significant difference in proliferation index in transition zone and peripheral zone carcinomas supports the morphological distinction of these tumour types and is consistent with differences in biological behaviour. The high proliferation index in lobules considered morphologically atrophic is reminiscent of previous observations in which carcinoma was spatially associated with atrophy.     

Proliferating cell nuclear antigen/cyclin in incidental carcinoma of the prostate

Monoclonal antibody to proliferating cell nuclear antigen (PCNA) has been used to identify the growth fraction in ten cases of benign prostatic hyperplasia (BPH), in 20 prostatic microcarcinomas (PMC) and in 30 cases of infiltrating prostatic carcinoma (PC). Ten year follow-up was available on all cases by means of clinical, serological, radiological and echographic examinations. The percentage of PCNA-staining nuclei was independently counted by two observers. Statistical analysis showed significant differences between PCNA/ cyclin score of BPH and PMC without recurrences with respect to those of PMC with progression and of PC. PCNA immunostaining may represent a reliable method for assessing cellular proliferative activity. It may be used as a more powerful diagnostic hallmark of PMC than patterns of non-malignant microglandular proliferation and is also a useful additional test for assigning histological grades to PMC and PC. Statistical analysis indicated that PCNA/cyclin index was an independent significant prognostic indicator of predicting malignant progression (P<0.01) and survival rates (P<0.05) of PC and PMC (>5 mm diameter).     

Immunohistochemical expression of prostate tumor overexpressed 1 in cystoprostatectomies with incidental and insignificant prostate cancer. Further evidence for field effect in prostatic carcinogenesis

Prostate tumor overexpressed 1 was recently identified as a novel gene and protein during a differential display screening for genes overexpressed in prostate cancer. It has been suggested that overexpression of prostate tumor overexpressed 1 can contribute to the proliferative status of prostate tumor cells and, thus, to their biologic behavior. Prostate tumor overexpressed 1 and Ki-67 were immunohistochemically evaluated in prostate cancer, high-grade prostatic intraepithelial neoplasia, and normal-looking epithelium in 20 cystoprostatectomies and 20 radical prostatectomies with pT2a Gleason score 6 prostate cancer. The aim was to see whether there were differences in marker expression between cystoprostatectomies and radical prostatectomies. The proportions of prostate tumor overexpressed 1– and Ki-67–positive cells in the cystoprostatectomies and radical prostatectomies increased from normal-looking epithelium through high-grade prostatic intraepithelial neoplasia, away from and adjacent to prostate cancer, to prostate cancer. Prostate tumor overexpressed 1 expression in prostate cancer in cystoprostatectomies was lower than in radical prostatectomies, the differences being significant; there were significant differences in Ki-67 indices. In conclusion, our findings related to prostate tumor overexpressed 1 expression in high-grade prostatic intraepithelial neoplasia, evaluated adjacent and away from prostate cancer, and in incidental and clinical cancers give further support to the concept of field effect in prostatic carcinogenesis as well as to differences in the process of prostatic carcinogenesis between cystoprostatectomies and radical prostatectomies.     

Decreased annexin I expression in prostatic adenocarcinoma and in high-grade prostatic intraepithelial neoplasia

AIMS: To analyse annexin I expression in prostatic carcinoma. Annexin I belongs to a family of structurally related calcium and phospholipid-binding proteins implicated in signal transduction, DNA replication, cell proliferation and apoptosis. The decreased expression of annexin I, II and VII proteins has been reported in different types of cancer. METHODS AND RESULTS: Using immunohistochemistry, we analysed annexin I expression in 77 cases of prostatic adenocarcinoma (Gleason score 6, N = 40; Gleason scores 7-8, N = 27; and Gleason scores 9-10, N = 10) and high-grade prostatic intraepithelial neoplasia (PIN, N = 50). Immunoreactivity of annexin I in tumour cells was evaluated as negative (< 5% of cells), focally positive (5-25% of cells) or positive (> 25% of cells). In contrast to positive staining in adjacent benign prostatic epithelium, annexin I expression was decreased (focally positive) in 76% of cases of high-grade PIN (P < 0.0001) and was decreased or absent in 81% of prostatic adenocarcinomas (P < 0.0001). Annexin I expression in all higher grade tumours (Gleason scores 7-10) was only focally positive or absent. CONCLUSIONS: Expression of annexin I inversely correlates with the increasing histological grade of prostatic adenocarcinoma. By showing a progressive loss of annexin I expression in high-grade PIN, intermediate-grade and high-grade cancer, our findings suggest that the loss of annexin I expression occurs early in prostatic tumorigenesis and becomes more prominent throughout tumour progression. The loss of expression of annexin I may serve as a useful marker of prostate cancer development and progression.     

Detection of prostatic cancer by solid-phase radioimmunoassay of serum prostatic acid phosphatase.

We compared our radioimmunoassay with the standard enzyme assay for prostatic acid phosphatase in the diagnosis of prostatic cancer. Serum samples from 50 controls, 113 patients with prostatic cancer, 36 with benign prostatic hyperplasia, 83 with other cancers, 20 with gastrointestinal disorders and 28 with total prostatectomies were randomized and studied by radioimmunoassay and enzyme assay. When the upper limit was set at 8.0 ng per milliliter (mean + 4 S.D.) the radioimmunoassay diagnosed prostatic cancer in 33, 79, 71 and 92 per cent of the patients with Stage I, II, III and IV disease. In contrast, the enzyme assay detected elevations of enzyme in the serum of 12, 15, 29, and 60 per cent respectively. No false-positive results were detected by either assay in normal controls but the radioimmunoassay test was positive in two patients with benign prostatic hyperplasia, in one patient after total prostatectomy, in nine with other cancers and in one of the group with gastrointestinal disorders. In contrast to the enzyme assay, the radioimmunoassay distinguished over half the cases of intracapsular prostatic cancer.     

Alpha-methylacyl-CoA racemase (P504S) expression in evolving carcinomas within benign prostatic hyperplasia and in cancers of the transition zone

Carcinomas of the transition zone (TZ) constitute approximately 20% of all prostate cancers. The TZ is the site of origin of grade 1 and grade 2 cancers, the most well-differentiated of the Gleason grade tumors, as well as for benign prostatic hyperplasia (BPH). In this regard, grade 1 carcinoma has architectural features that closely mimic gland-rich BPH nodules. Although a relationship between cancers arising in this zone and BPH has been suspected, such an association remains undefined. To gain insight into the origin, development, and progression of cancers arising in the TZ, we used a highly specific rabbit monoclonal antibody (P504S) directed against alpha-methylacyl-CoA racemase (AMACR) to study the expression of the enzyme in 25 cases of evolving and fully developed carcinomas of this zone. AMACR has been proposed as a new molecular marker for prostate cancer, because the enzyme is reportedly overexpressed in high-grade dysplasias, also termed prostatic intraepithelial neoplasia, a purported precursor of prostatic carcinoma, and in all grades of prostatic carcinoma of the peripheral zone. Using P504S, P63, or antikeratin 34beta E12 antibodies, we found it possible to define areas of transition from hyperplasia to carcinoma in 6 BPH nodules. In 3 other cancer-containing BPH nodules, staining for AMCAR was observed in benign hyperplastic glands that were juxtaposed to carcinoma. Enzyme expression was also evident in 5 additional cases in which BPH was found adjacent to cancer. In contrast; AMACR was not visualized in any other BPH nodules that we studied. Thus, using the enzyme as a marker, we document for the first time that some carcinomas of the TZ arise from an AMCAR-positive transition lesion within a subset of BPH nodules. Moreover, the finding of enhanced AMACR expression in benign glands within cancer-containing nodules as well as in BPH lesions adjacent to carcinoma suggests that in some cases, up-regulation of the enzyme may precede morphological evidence of neoplastic transformation. AMACR was lightly expressed in transition lesions and grade 1 carcinomas but more strongly expressed in higher-grade TZ cancers, suggesting that enzyme expression is enhanced with progression in this zone. Because AMACR is involved in the beta oxidation of branched fatty acids and their derivatives, enhanced expression of the enzyme in evolving carcinomas in BPH nodules, as well as its up-regulation in juxtaposed morphologically benign glands and grade 1 carcinomas, suggests that increased utilization of fatty acids may play an important role in carcinoma development and progression in the TZ.     

临床A期前列腺癌的病理特征和漏诊误诊原因分析

目的探讨临床A期前列腺癌的病理特征,并分析其好发部位及漏诊误诊原因.方法复查上海地区5所医院1 020份前列腺切除标本,通过免疫组织化学SP法检出50例临床A期前列腺癌,根据肿瘤分化程度及容量分出A1期癌12例和A2期癌38例,比较病理形态差异,分析A1和A2期癌的漏诊误诊原因.结果 A1期癌以低中级别、低容量、多灶性生长为特点,A2期癌以高中级别、高容量、高浸润性伴高级别上皮内新生物为特征.在漏诊误诊的8例A期癌中,A1期癌占7例,均误诊为良性增生性小腺泡病变.A2期癌1例误诊为反应性上皮样组织细胞增生.结论 A1期癌大多在增生的前列腺移行带和中央带组织易被发现,A2期癌可能是大多原发于周围带的高中级别癌浸润至前列腺中央区域.国内A期癌检出率低的原因主要是因为标本取材量少和A1期癌漏诊率较高.     

Heterogeneous expression of alpha-methylacyl-CoA racemase in prostatic cancer correlates with Gleason score

AIMS: Alpha-methylacyl-CoA racemase (AMACR) is a sensitive and specific immunohistochemical marker of prostatic malignancy, staining 80-100% of prostatic cancers with absent staining in benign glands. However, positive staining in benign conditions as well as low rates of AMACR reactivity in prostatic cancer variants have been described. Preliminary use of AMACR immunohistochemistry in our institution has suggested lower specificity and sensitivity for prostatic cancer than initially proposed. The aim of this study was to establish true rates of AMACR reactivity in prostatic cancer and benign prostatic hyperplasia (BPH). METHODS AND RESULTS: AMACR immunohistochemistry was performed on sections from 57 prostatic cancers and 44 BPH resections. Ninety-one percent of cancers were AMACR+, with diffuse (> 75%) tumour staining in 53% of cases. Thirty-eight percent of tumours showed heterogeneous expression (1-75% tumour staining). This was significantly correlated with increased Gleason score. High-grade prostatic intraepithelial neoplasia (PIN) was AMACR+ in 87% of cancers. Eleven percent of BPH showed moderate or strong staining in benign glands, focally mimicking the malignant staining pattern. CONCLUSIONS: This study confirms heterogeneous AMACR expression in prostatic cancer and shows a correlation with Gleason score. Positive staining in BPH is also documented, thus emphasizing the importance of interpreting AMACR immunohistochemistry in the context of other findings in a diagnostic setting.     

Highly proliferative intratumoral fibroblasts and a high proliferative microvessel index are significant predictors of tumor metastasis in T3 ulcerative-type colorectal cancer

Fibroblast and endothelial cell mitotic figures are seen in some areas of colorectal cancers, and the purpose of this study was to investigate whether the proliferative activity of fibroblasts and endothelial cells plays an important role in tumor progression of T3 ulcerative-type colorectal cancer. The tumor area of 157 colorectal cancers was divided into marginal elevated area and central depressed area (CDA), and at half the depth of the depression the CDA was in turn divided into CDA upper area (CDAU) and CDA lower area (CDAL). The proliferative activity of the tumor cells, fibroblasts, and endothelial cells was assessed immunohistochemically by double CD31/MIB-1 (anti--Ki-67 antigen) staining. The proliferative microvessel index was estimated as the percentage of microvessels lined by MIB-1-positive endothelial cells relative to the total microvessel count. Proliferative activities of tumor cells showed significant associations with those of fibroblasts and the proliferative microvessel indices in all of the corresponding areas. Proliferative activities of fibroblasts also showed significant associations with proliferative microvessel indices in all of the corresponding areas. Colorectal cancers with nodal metastasis showed significantly higher proliferative activities of fibroblasts in the CDAU than those without nodal metastasis (P <.001). The high proliferative activities of fibroblasts and proliferative microvessel indices in the CDAU showed significant associations with short distant organ metastasis-free periods in colorectal cancers without nodal metastasis (P <.001 and P =.010, respectively) and those with nodal metastasis (P =.024 and P =.036, respectively). Multivariate analysis showed that the highly proliferative fibroblasts in the CDAU significantly increased hazard rates of distant organ metastasis of colorectal cancer patients with nodal metastasis (P =.018). Proliferative activities of fibroblasts and endothelial cells in the CDAU are useful parameters for predicting tumor metastasis in patients with T3 ulcerative-type colorectal cancer. HUM PATHOL 32:401-409.     

Proliferation and apoptosis of epithelium in prostate cancer,in a peritumor region,and in benign hyperplasia

Indices of Ki67, Bc12 expression, mutant gene p53, nucleolar organizers activity and the percentage of cells having nucleic acids levels higher or lower of the diploid levels were determined in prostatic epithelium in cancer, in the peritumorous area and in the area of benign prostatic hyperplasia. A considerable variability of the tumor epithelium by the level of proliferative activity, apoptosis inhibition and expression of mutant p53 gene was established. Increased proliferative activity and predominance of epitheliocytes with a nucleic acids level higher as compared to the diploid one were revealed in the tumor epithelium. Low apoptosis inhibition and increased degradation of the epithelium in case of a high level of Ki-67 expression index were noted in the peritumorous area. Changes in the peritumorous region were noticed both very close to the tumor lesion as well as at considerable distance from it.     

Overexpression of Pim-1 during progression of prostatic adenocarcinoma

AIMS: Pim-1 is a serine/threonine kinase that has been shown to play an integral role in the development of a number of human cancers, such as haematolymphoid malignancies. Recently, evidence has shown Pim-1 to be important in prostatic carcinogenesis. In order to further our understanding of its role in prostate cancer, we investigated Pim-1 expression in normal, premalignant, and malignant prostate tissue. METHODS: Using immunohistochemistry, Pim-1 expression was analysed in prostate tissue from 120 radical prostatectomy specimens. In each case, Pim-1 staining was evaluated in benign prostatic epithelium, high grade prostatic intraepithelial neoplasia (PIN), and prostatic adenocarcinoma. The number of positively staining cells was estimated, and the intensity of staining was scored on a scale of 0 to 3+. RESULTS: Pim-1 immunoreactivity was identified in 120 cases (100%) of adenocarcinoma, 120 cases (100%) of high grade PIN, and 62 cases (52%) of benign glands. The number of cells staining in benign epithelium (mean 34%) was much lower than that in high grade PIN (mean 80%; p<0.0001) or adenocarcinoma (mean, 84%; p<0.0001). There was no significant difference between high grade PIN and adenocarcinoma in the percentage of cells staining positively for Pim-1 (p = 0.34). The staining intensity for Pim-1 was significantly lower in benign prostatic epithelium than in PIN and adenocarcinoma (p<0.001). There was no statistically significant correlation between the level of Pim-1 expression and Gleason score, patient age, tumour stage, lymph node metastasis, perineural invasion, vascular invasion, surgical margin status, extraprostatic extension, or seminal vesicle invasion. CONCLUSIONS: Pim-1 expression is elevated in PIN and prostatic adenocarcinoma compared with benign prostatic epithelium. This finding suggests that upregulation of Pim-1 may play a role in prostatic neoplasia.