Poor prognostic value of proliferating cell nuclear antigen labelling index in breast carcinoma

Canine Mammary Tumors as a Potential Model for Human Breast Cancer in Comparative Oncology

Clinical and molecular similarities between canine mammary tumors (CMTs) and human breast cancer (HBC) propel scientists to further study their application in comparative oncology as a model for human breast cancer. In total, 64 canine mammary tumors were selected to study the most common markers, which are applicable for human breast cancer treatment, including estrogen and progesterone receptors (ER and PR), human epidermal growth factor (HER2/neu), Ki67, and cyclooxygenase 2 (Cox2). Immunohistochemistry (IHC) was used to assess the protein expression. The Veterinary Nottingham Prognostic Index (Vet-NPI) was also computed. Moreover, univariate and multivariable Cox proportional hazard analyses were applied to estimate hazard ratios (HRs). The results demonstrated that Ki67 was strongly expressed in the triple-negative tumors, and Ki67 protein expression continuously increased over the increase of Cox2 protein expression (p < 0.001). Further analysis revealed a significant difference among canine mammary subtypes and Vet-NPI, in which triple-negative tumors displayed the highest mean score compared to other subtypes (p < 0.001). In addition, the multivariable analysis revealed that the regional mastectomy procedure (adjusted HR = 2.78 (1.14-6.8)), the triple-negative tumors (adjusted HR = 48.08 (7.74-298.8)), strong Ki67 protein expression group (adjusted HR = 7.88 (2.02-30.68)), and strong Cox2 protein expression group (adjusted HR = 29.35 (5.18-166.4)) demonstrated significantly lower disease-free survival rates compared to other corresponding groups. Overall, canine mammary tumors showed strong similarities to human breast cancer in terms of clinical and molecular aspects; therefore, they could be suggested as a model for human breast cancer in comparative oncology.

Canine mammary tumors as a model for human disease

Animal models for examining human breast cancer (HBC) carcinogenesis have been extensively studied and proposed. With the recent advent of immunotherapy, significant attention has been focused on the dog as a model for human cancer. Dogs develop mammary tumors and other cancer types spontaneously with an intact immune system, which exhibit a number of clinical and molecular similarities to HBC. In addition to the spontaneous tumor presentation, the clinical similarities between human and canine mammary tumors (CMT) include the age at onset, hormonal etiology and course of the diseases. Furthermore, factors that affect the disease outcome, including tumor size, stage and lymph node invasion, are similar in HBC and CMT. Similarly, the molecular characteristics of steroid receptor, epidermal growth factor, proliferation marker, metalloproteinase and cyclooxygenase expression, and the mutation of the p53 tumor suppressor gene in CMT, mimic HBC. Furthermore, ductal carcinomas in situ in human and canine mammary glands are particularly similar in their pathological, molecular and visual characteristics. These CMT characteristics and their similarities to HBC indicate that the dog could be an excellent model for the study of human disease. These similarities are discussed in detail in the present review, and are compared with the in vitro and other in vivo animal models available.

Minichromosome maintenance protein 2 is a reliable proliferative marker in breast carcinoma

This is a study aimed to examine the distribution pattern of a specific minichromosome maintenance protein 2 (MCM2) in benign and malignant breast tissue. We also aim to correlate the frequency of expression of MCM2 with the degree of tumor differentiation. We used immunohistochemistry to examine the distribution and expression pattern of MCM2 on formalin-fixed paraffin-embedded tissue sections of benign (n = 30) and malignant breast tissue (n = 70) (IDC 56, DCIS 4, ILC 2, nonductal 4, mixed type 4). We quantified MCM2 expression by calculating a labeling index, which represents the percentage of epithelial nuclei that stained positively. Immunoreactivity was heterogenous in all the 70 malignant cases examined. Epithelial cells in cycle are most frequent at the tumor periphery. Labeling index of MCM2 was greatest in grade 3 (poorly differentiated) and lowest in grade 1 tumors (well differentiated). Minichromosome maintenance protein 2 expression in breast cancer showed a positive association with histologic grade (P < .05). In all the benign breast tissue examined, no proliferating compartments could be characterized. Minichromosome maintenance protein 2 is a useful proliferative marker of breast carcinoma. The frequency of expression of MCM2 showed an inverse correlation with the degree of tumor differentiation.

Prognostic value of proliferation in invasive breast cancer: a review

Breast cancer is the leading cause of death among solid tumours in women, and its incidence is increasing in the West. Adjuvant chemotherapy and hormonal treatment improve survival but have potentially serious side effects, and are costly. Because adjuvant treatment should be given to high risk patients only, and traditional prognostic factors (lymph node status, tumour size) are insufficiently accurate, better predictors of high risk and treatment response are needed. Invasive breast cancer metastasises haematogenously very early on, so many breast cancer prognosticators are directly or indirectly related to proliferation. Although studies evaluating the role of individual proliferation regulating genes have greatly increased our knowledge of this complex process, the functional end result-cells dividing-has remained the most important prognostic factor. This article reviews the prognostic value of different proliferation assays in invasive breast cancer, and concludes that increased proliferation correlates strongly with poor prognosis, irrespective of the methodology used. Mitosis counting provides the most reproducible and independent prognostic value, and Ki67/MIB1 labelling and cyclin A index are promising alternatives that need methodological fine tuning.

Histamine, mast cells and tumour cell proliferation in breast cancer: does preoperative cimetidine administration have an effect?

Endogenous histamine has been shown to effect growth mechanisms in experimental mammary carcinomas via H2 membrane receptors (Cricco et al, 1994). Both H1 and H2 binding sites are present in human mammary glands but only 75% malignant carcinomas express H2 receptors (Lemos et al, 1995). The presence of mast cells around tumour tissue raises questions concerning the source of histamine in breast tumour tissue. While cimetidine, an H2 antagonist, has been shown to influence the presence of tumour infiltrating lymphocytes (TIL) in colorectal cancer (Adams and Morris, 1994, 1997) that was not found to be the case in breast cancer (Ng et al, 1995). In recent studies tumour cell proliferation, as measured by Ki-67 antibody labelling, has been seen as an additional prognostic indicator in breast cancer (Railo et al, 1993, 1997; Ferno, 1998; Schauer et al, 1998). We investigated the possibility that cimetidine may influence tumour proliferation by blocking the growth-promoting effects of histamine. No relationship between preoperative cimetidine administration and tumour cell proliferation was seen overall. A weak correlation was seen between tissue histamine content and mast cell count which was not influenced by cimetidine. Tumour cell proliferation correlated well with other prognostic indicators such as grade and differentiation.

Proliferating cell nuclear antigen (PCNA) immunolabeling as a prognostic factor in invasive ductal carcinoma of the breast in Taiwan

To evaluate the prognostic significance of proliferating cell nuclear antigen (PCNA) in breast cancer, an immunohistochemical assay was performed in 150 patients with invasive ductal carcinomas. The PCNA labeling index (PCNA-LI) was classified into two subgroups at a cut-off point of 45% that gave the best prognostic estimates for PCNA in survival analyses. Seventy-eight tumors had a low PCNA-LI of < or =45% and 72 tumors had a high PCNA-LI of >45%. A high PCNA-LI correlated significantly with p53 overexpression (P<0.03), positive axillary node (P<0.04), short disease-free survival (P<0.001) and overall survival (P<0.0002), but not with other factors. In multivariate analysis, the PCNA-LI predicted the disease-free (P<0.008) and overall survival (P = 0.0007) independently. Our study indicates that the PCNA-LI has independent prognostic value.

The prognostic value of proliferating cell nuclear antigen (PCNA) in the advanced cancer of larynx

It was retrospectively examined whether the tumor growth fraction determined by PCNA score in the advanced cancer of larynx could be used as a prognostic factor. There was used immunohistochemical method to evaluate the PCNA score of positive cells in paraffin embedded tissues of laryngeal carcinoma obtained from 90 patients. They were treated by surgery in the Department of Otolaryngology at the Medical University in Cracow, Poland in 1987 and 1988. The follow-up period was not shorter than 5 years. In the examined material there were 59 patients with tumor T3 and 31 with T4. Neck dissection on one or on both sides was performed on patients. The metastases in regional lymph nodes was found in 26 patients. Histologic grading (G1 = 18, G2 = 52 and G3 = 20 patients) and number of mitosis was assessed. The PCNA score was defined by counting positive cells and presented as percentage of a cells. It ranged from 2.1 to 73.0% with the average value of 34.5%. The PCNA score below this level was defined as a low PCNA score (49 patients) and above this level as a high PCNA score (41 patients). There was a correlation between PCNA score and survival of the patients. 35 patients (71.4%) with low PCNA score survived and 15 (36.6%) with high PCNA score (P < 0.05). Similarly the high PCNA score influenced the number of metastases in lymph nodes. They occurred in low and high PCNA score respectively at nine (18.4%) and 17 patients (41.5%) (P < 0.05). There was not found any correlation between PCNA score and tumor differentiation, its size and mitosis number. The PCNA may be a prognostic factor for the patients with advanced cancer of larynx.

Immunohistochemical detection of Ki-67 and PCNA in canine mammary tumors: relationship to clinical and pathologic variables

The objectives of this study were to measure the proliferation indices in canine mammary tumors using immunohistochemical detection of Ki-67 and proliferating cell nuclear antigen (PCNA), to determine the relationship of these antigens to clinical and pathologic variables, and to investigate the usefulness of these antigens as prognostic indicators. Ninety-six female dogs with 115 primary nonmetastasized spontaneous mammary tumors and dysplasias were included in the study. Immunostaining was performed using MIB-1 and PC10 monoclonal antibodies against Ki-67 and PCNA, respectively. Ki-67 and PCNA proliferation indices were determined. Dogs were followed for 18 months, with clinical examinations every 3-4 months. There was a significant correlation between Ki-67 and PCNA indices in the dogs with dysplasias and benign tumors but not in the dogs with malignant tumors. The clinical stage at first presentation was related to the proliferative index measured with Ki-67 but not to that measured with PCNA. Proliferation indices were significantly lower in the nonmalignant tumors and dysplasias than in the malignant tumors. In malignant tumors, the PCNA index had a positive correlation with the histologic malignant grade and the nuclear grade. High index values of Ki-67 were positively correlated with metastasis, death from neoplasia, low disease-free survival rates, and low overall survival rates. PCNA displayed no significant association with these variables. Multivariate analyses concerning metastasis, disease-free survival, and overall survival revealed that the Ki-67 index had prognostic value.

Rapid and prognostically valid quantification of immunohistochemical reactions by immunohistometry of the most positive tumour focus. A prospective follow-up study on breast cancer using antibodies against MIB-1, PCNA, ER, and PR

The prognostic significance of immunohistochemical markers for cell proliferation [MIB-1, proliferating cell nuclear antigen (PCNA)] and hormone receptor analysis [oestrogen receptor (ER), progesterone receptor (PR)] was tested by means of immunohistometry in a series of 103 breast cancer patients in comparison with the lymph node status N, the tumour size T, histomorphological grading, and the biochemical ER and PR status. Immunohistochemical reactions were performed on 2 microns sections from paraffin-embedded tissue, using an indirect peroxidase method. The proportion of immunostained tumour cell nuclei was determined using a TV-image analysis system. Measurements were performed using a 20 x objective on 40 viewing fields (1.94 mm2, MIB-1 and PCNA) or 20 viewing fields (0.97 mm2, ER and PR). The mean immunopositivity of all viewing fields and the value of the most immunopositive viewing field (MIB-1max, PCNAmax, PRmax, ERmax) were calculated. The mean values and the maximal values were highly correlated (r = 0.903, P < 0.001). After 1:2:1 quantilization, 84.2 per cent of the 412 single measurements revealed mean and maximal values in the same category (P < 0.0001). For each of the four immunohistochemical markers, the prognostic significance of the maximal values was higher than that of the mean values. The highest prognostic significance was found for MIC-1max (P = 0.0002), followed by PRmax (P = 0.0046), ERmax (P = 0.0154), and PCNAmax (P = 0.0161). From the results of a Cox model, a 'prognostic index (PI)' was developed, ranging from -1 to 8: PI = 2 x N + T + MIB-1max-PRmax. The four groups of patients with PI values of < 2, 2-3, 4-5, and > 5 revealed significantly different 7.5-year survival probabilities (P < 0.0001). The simplicity of the PI makes it a clinically useful, routinely applicable, and understandable parameter in the surgical pathology of breast carcinoma.

Cellular proliferation in breast ductal infiltrating carcinoma. Correlation with clinical and histopathological variables

To evaluate four methods to study cellular proliferation (mitotic count, mitotic index, PCNA and MIB1) in a series of breast ductal invasive cancer NOS, and the possible correlations between these different methods and other pathological variables, we studied 110 ductal invasive carcinomas NOS specimens. Mitoses per 1000 tumor cells and per 10 HPF, and immunostaining for PCNA and MIB1 were evaluated. Other accepted prognostic factors such as tumor size, histologic grade, estrogen and progesterone receptors measured by immunostaining and axillary status were obtained. Correlation between the four methods to evaluate cellular proliferation and these other variables was performed. Mitotic count, mitotic index, PCNA and MIB1 showed a good rate of correlation (r = 0.71-0.53, p < 0.05), with the exception of MIB1-mitotic index which was weak (r = 0.38, p < 0.05). A strong association between cellular proliferation, with independence of the method applied, and histologic grade, ER and PR was obtained. No association was observed with tumor size and lymph node involvement. In conclusion, there was a strong correlation between the four methods to evaluate cellular proliferation. Mitotic count (per 10 HPF) and MIB1 show a better correlation with other morphological variables. None of the evaluated methods are associated with the tumor size and axillary status, suggesting that mitotic count is the most accurate method to analyse cellular proliferation in routine practice.

How should PCNA be assessed? Total of stained cells or only the most intensely stained ones?

OBJECTIVE

This study aimed to analyse whether a marker of proliferative activity (PCNA) could provide a prognosis of tumor evolution and to determine whether different interpretation criteria could alter the results.

METHOD

The presence of PCNA in 59 patients of state II (T2 N0.1 M0) mammary carcinoma was determined.

RESULT

Numerical proportions of total and intensely stained cells were established. These data were compared with anatomopathological parameters. A significant association between higher cyclin values and worse histological and nuclear grading was encountered, particularly in patients with a "negative axilla" using the PCNA index. Cyclin values were not significant in relation to any parameters when indices from the intensely stained cells were considered exclusively.

CONCLUSION

Higher nuclear (NG3) and histological (HGIII) grading, associated with a high PCNA index (> 50), distinguish high-risk patients, and it is more appropriate considering all the stained cells as representative of PCNA indices, thus reflecting tumor aggressiveness.

Immunohistochemical study on the prognostic value of MIB-1 in gastric carcinoma

The prognostic significance of tumour cell proliferation was investigated in a series of 418 gastric carcinomas using the monoclonal antibody MIB-1. Owing to strong intratumoural heterogeneity of MIB-1 expression three different proliferation indices (PIs) were determined in all carcinomas: (1) PImax in areas of maximal tumour cell proliferation, (2) PIrand in areas randomly distributed over the whole tumour. (3) PIfront in areas exclusively located at the tumour invasion front. There was a strong intertumoral heterogeneity with PImax ranging from 4.9% to 92.2%, PIrand ranging from 3.4% to 81.4% and PIfront ranging from 4.2% to 87.1%. The mean values were 51.3% +/- 19.7 for PImax, 34.2% +/- 18.3 for PIrand and 37.2% +/- 19.5 for PIfront. Whereas no statistically significant correlation could be found between proliferative activity and the clinicopathological parameters depth of invasion, lymph node involvement or grade of tumour differentiation, there was a positive correlation between a high proliferation index at the tumour invasion front (PIfront) and the presence of blood or lymphatic vessel invasion. No significant correlation could be demonstrated between the different proliferation indices and survival, even when different subgroups of patients were analysed separately. The present results suggest that the immunohistochemical evaluation of the proliferation activity has no predictive value for the prognosis of gastric cancer patients or the identification of subgroups of patients who may be at higher risk.

Immunohistochemical study of Cell Cycle Modulators in G(1)-S Transition in Clinical Breast Cancer Tissue

In the present study, we investigated immunolocalization of the modulators of G(1)-S transition by using monoclonal or polyclonal antibodies for each of the modulators in 65 cases of clinical breast cancer. Two prominent cyclin dependent kinase(cdk)-cyclin complexes, cdk4-cyclin D and cdk2-cyclin E, were proved to have different modes of mutual expression. cdk4-positive lesions were found to equal cyclin D-expressing lesions in 55 cases, while the former were more extensive than the latter in 9 cases. On the other hand, cyclin E expression was detected in all the cases examined and was more dominant than that of cdk2/cdc2 in as many as 40 cases whereas the reverse was seen in only 1 case. Interestingly, cdk4(P<0.01)and cyclin E(P<0.05)expressions showed an inverse relationship with the tumor size and the cancer stage. A similar tendency was also detected for two other positive modulators of G(1)-S transition, indicating that cell cycle progression must be regulated by the cancer itself once it has grown to a certain extent. p21, which has been regarded as a universal inhibitor of the cell cycle, was expressed in 43.1% of the cases examined and its immunoreactivity showed an inverse relationship with lymph node metastasis(P<0.05). It also tended to be absent more frequently in T3 or larger cancers and stage III cases. Moreover, two patients who died as a result of cancer and three patients with recurrence were all p21 negative, suggesting that p21 is prognosticably the most significant of all these modulators.

Expression of Ki-67 antigen and proliferative cell nuclear antigen in benign and malignant epithelial lesions of the larynx

In an attempt to analyse the proliferative activity in benign and malignant laryngeal epithelial lesions, and to determine the relationship to their histologic grade, we studied the expression of proliferative cell nuclear antigen (PCNA) and Ki-67 antigen on 20 squamous carcinomas, and on 30 biopsies of epithelial hyperplasia categorized according to the Kambic-Lenart classification into simple, abnormal, and atypical hyperplasias. In simple hyperplasia, both antibodies stained the nuclei of the occasional cells in the basal layer. In abnormal hyperplasia (mild dyplasia), positive cells occupied up to a third, and in atypical hyperplasia (moderate and severe dysplasia) they occupied from two-thirds to the entire epithelial thickness. In squamous carcinoma, we have found a statistically significant correlation between its grade and the percentage of Ki-67-(p < 0.01) and PCNA-(p < 0.00001) positive cells. Our results suggest that the proliferative fraction progressively increases with the degree of epithelial hyperplasia and the grade of carcinoma. We conclude that the patterns of immunoreactivity to PCNA and Ki-67 antigen correspond to the histologic grade of both benign and malignant epithelial lesions of the larynx. This method should be regarded as a useful adjunct to traditional histological techniques allowing more objective grading of benign and malignant epithelial lesions.

Proliferating cell nuclear antigen (PCNA) in relation to ras, c-erbB-2,p53, clinico-pathological variables and prognosis in colorectal adenocarcinoma

Proliferating cell nuclear antigen (PCNA) expression was studied by immunohistochemistry on paraffin-embedded sections of 293 primary colorectal adenocarcinomas and 56 corresponding lymph node metastases. PCNA-positive expression was detected in <25% of tumour cells in 172 (59%) cases and in > 25% in 121 (41%) cases. PCNA accumulation was related to over-expression of c-erbB-2 and p53 and tended to be increased in cases with ras over-expression. PCNA expression was identical in primary and corresponding metastases. No significant relationship was observed between PCNA expression and prognosis and other clinico-pathological variables, including grade of differentiation, growth pattern, Dukes' stage, site, age or sex. We conclude that PCNA expression may be related to alterations of oncoproteins but that PCNA itself could not provide additional information for the development of metastasis and prognosis in colorectal adenocarcinoma.

Assessment of cellular proliferation of eccrine acrospiromas and eccrine sweat gland carcinomas by AgNOR counting and immunohistochemical demonstration of proliferating cell nuclear antigen (PCNA) and Ki-67

Argyrophil nucleolar organizer regions (AgNORs) were counted and immunostaining using antibodies raised against proliferating cell nuclear antigen (PCNA) and Ki-67 was carried out on eccrine acrospiroma and eccrine sweat gland carcinoma, to determine the malignant potential and prognosis of these tumours. Formalin-fixed and paraffin-embedded tissue specimens surgically excised from 25 patients with eccrine sweat gland carcinoma (20 cases of eccrine porocarcinoma, four cases of ductal sweat gland carcinoma and one case of malignant clear cell hidradenoma) and 25 patients with eccrine acrospiroma (16 cases of eccrine poroma, four cases of poroid hidradenoma and five cases of clear cell hidradenoma) were used. PCNA and Ki-67 labelling indices were categorized semiquantitatively into four grades. Significant differences were noted between eccrine sweat gland carcinoma and eccrine acrospiroma with these three methods (P < 0.01). When a cut-off of 5 was chosen, the AgNOR value distinguished eccrine sweat gland carcinoma from eccrine acrospiroma with high specificity and sensitivity. Moreover, we compared the results of these three methods between stages 1 or 2 (17 cases) and stage 3 (eight cases) eccrine sweat gland carcinomas, and no significant differences were observed. From these findings, these three methods are useful in discriminating malignant from benign lesions of eccrine tumours, but have no value in estimating the aggressiveness of eccrine sweat gland carcinomas.

The proliferating cell nuclear antigen index in breast carcinomas does not correlate with mitotic index and estrogen receptor immunoreactivity

To investigate the expression of a marker of cell proliferation (PCNA/Cyclin) and its putative relationship with histological grading, mitotic index and estrogen receptor immunoreactivity, we studied twenty-seven cases of invasive breast carcinoma in formalin-fixed, paraffin-embedded tissue sections. The PCNA and estrogen receptor were detected by the PC 10 and H 222 monoclonal antibodies respectively, using an avidin-biotin-peroxidase method. The median value of PCNA index was 20.9% with a range from 1.4 to 84.2%. We did not find any significant relationship between PCNA index and the histological grading, mitotic index and estrogen receptor immunoreactivity. We conclude that PCNA detected by the monoclonal antibody PC 10 in formalin-fixed material looks at present unreliable as a proliferation marker in breast carcinoma.

Cell kinetics in human breast cancer: comparison between the prognostic value of the cytofluorimetric S-phase fraction and that of the antibodies to Ki-67 and PCNA antigens detected by immunocytochemistry

The determination of cell proliferation is one of the more widely used tools for assessing prognosis. However, additional research in this field is warranted because today there are several methodological procedures available for monitoring cell kinetics and it has still not been established which is the most reliable marker of proliferation and which possesses the greatest prognostic value. We performed this study in a series of primary invasive breast cancers to compare the prognostic value of S-phase fraction (SPF) by flow cytometry, the most widely used method for detecting proliferation at present, with that of antibodies to Ki-67 and PC-10 to proliferating-cell nuclear antigen (PCNA) detected by immunocytochemical methods. A significant linear relationship was observed only between SPF and Ki-67. In univariate analysis SPF and Ki-67 values, nodal status, histological grading and peritumoral lymphatic-vessel invasion were significant predictors of relapse-free survival (RFS). As far as overall survival (OS) is concerned, only SPF, Ki-67 and nodal status were significantly associated with the risk of death. PCNA had no prognostic value for either RFS or OS. In multivariate analysis only SPF and nodal status retained a significant and independent prognostic value. Neither the cell-kinetics parameters assessed by immunocytochemistry (i.e. Ki-67 and PCNA) nor histological grading were independent prognosticators. In conclusion, our results provide evidence that the determination of SPF by flow cytometry was the strongest cell-kinetics marker used to assess prognosis in this series of breast cancers. However, different and novel markers of cell kinetics need to be compared in larger series in order to identify the best one.