High Proliferating Cell Nuclear Antigen Research Articles

Estudio de la expresión del antígeno nuclear de proliferación celular y pl85 en el carcinoma no microcítico de pulmón

We assessed immunohistochemical expression of p185 and the proliferating cell nuclear antigen (PCNA) in 68 patients undergoing surgery for non-small cell lung cancer. Adenocarcinoma of the lung was the histological type whose expression of p185 at levels exceeding 10% was greater to a statistically significant degree. Epidermoid carcinoma, on the other hand, was associated with the highest PCNA indices. Although these 2 markers had no prognostic value in the survival study, it must be pointed out that the longest survivors were patients with p185 expression less than 10% in neoplastic cells.

Cytometric Characteristics and Proliferation of Inverted Papillomas of the Paranasal Sinuses

Inverted papillomas are rare tumors of unknown histologic origin occurring in the nasal cavity and the paranasal sinuses. Specimens from 27 patients with histologically confirmed inverted papillomas were assessed by DNA analysis and immunohistochemical identification of the proliferating cell nuclear antigen (PCNA). One of the patients had squamous cell carcinoma associated with the inverted papilloma. According to the results of DNA analysis, patients with inverted papillomas would be divided into two groups. One group demonstrated low DNA indices and a low PCNA score. The second group showed higher DNA values associated with an increased proliferation rate. Two patients from each group developed recurrent disease. The recurrent papillomas from the patients in the first group demonstrated the same low DNA indices as were observed in the primary tumors. The recurrences from the patients in the second group occurred 1.5 and 2 years, respectively, following the primary surgery. Although the primary tumors had high DNA indices, the recurrences demonstrated a further increase of the DNA indices with cytological signs of malignancy. Quantitative DNA analysis and PCNA scoring offers a new, reliable means of assessing inverted papillomas and may possibly predict those tumors that behave more aggressively. Close follow up of patients presenting with high DNA indices and elevated PCNA scores is recommended.

Relationship of genetic instability with immunoreactivities for p53 protein and proliferating cell nuclear antigen in transitional cell carcinoma of the bladder.

To elucidate the relationship between genetic instability and tumor development in transitional cell carcinoma (TCC) of the bladder. The genetic instability as assessed by 2c deviation index (2cDI) and 5c exceeding rate (5cER) was compared with immunoreactivities for p53 protein and proliferating cell nuclear antigen (PCNA) in specimens obtained from 65 patients with primary untreated TCCs. Both p53 and PCNA immunoreactivities significantly correlated with histological grade as well as stage. The immunoreactivity of p53 significantly correlated with that of PCNA, while a dissociation of the positive correlation between p53 immunoreactivity and PCNA expression was noted in the TCCs with high 2cDI value (> or = 2.0) and/or high 5cER (> or = 10%). In addition, PCNA expression became higher as the genetic instability increased, however, the p53 immunoreactivity was not parallel with the change of genetic instability. Moreover, some TCCs with high genetic instability (2cDI > or = 2.0 and 5cER > or = 10%) showed concomitant expression of high PCNA and low p53 protein, whose clinical outcome was poor in general. The inactivation of p53 may represent a rather early event in the development of TCC of the bladder. However, the proliferative activity in itself rather than the effect due to a specific alteration in p53 plays an important role in the development and progression in TCC of the bladder.

Detection of Ras Oncogene Point Mutations and Simultaneous Proliferative Fraction Estimation in Gallbladder Cancer

Gallbladder cancer is notorious for its poor clinical evolution; so, a study of parameters with any prognostic potential is of particular interest. In this study, we investigated 23 adenocarcinomas regarding both the presence of point mutations in the ras gene family and the quantitative expression of Proliferating Cell Nuclear Antigen (PCNA). We respectively used molecular biology techniques and immunohistochemistry. Our results were related to several clinicopathologic determinators as well as to patients' survival. Mutations in codon 12 of the K-ras gene were detected in four gallbladder neoplasms (17%). This specific type of mutation is likely to be partially involved in this organ's tumourigenesis, particularly since no H-ras codon 12 or K-ras codon 13 (aspartic acid) mutations were detected in any of our specimens. PCNA immunoreactivity was generally limited in all tumours studied except for those morphologically characterized as being particularly aggressive. Notably, the four tumours in which K-ras mutation was detected, demonstrated relatively high PCNA positive immunoexpression in their malignant cells. This finding reinforces a possible correlation between the presence of ras mutations and increased cell growth. Staging was the only factor which was statistically associated with survival (p < 0.01). Therefore, the poor evolution of this cancer is probably due to late diagnosis and not related to a model of increased biologic aggressiveness.

Expression of proliferating cell nuclear antigen in premalignant lesions of the larynx

Purpose: This study was performed to 1) evaluate the proliferative activity in premalignancies of the larynx by immunostaining for proliferating cell nuclear antigen (PCNA), 2) to examine the relationship between PCNA expression and histological diagnosis and 3) to evaluate clinical values of PCNA immunostaining. Materials and Methods: The percentage of PCNA-positive nuclei (PCNA index) and their highest location (PCNA grade) were evaluated in 44 specimens of premalignant lesions, 7 premalignant lesions near carcinomas, 9 normal epithelium, and 12 early invasive carcinomas of the larynx. Follow-up was conducted. Results: The mean of PCNA indices in premalignancies was significantly higher than in normal epithelium but lower than in early invasive carcinomas. PCNA index had no apparent correlation with the histological diagnosis, but in the same case, the higher degree of dysplasia showed higher PCNA index. PCNA grade showed significant correlation with the histological diagnosis. Cases with higher PCNA expression showed higher percentages of recurrence and cancerization. Premalignant lesions near carcinomas presented significantly high PCNA expression. Conclusions: The proliferative activity in premalignancies of the larynx is higher than in normal epithelium and lower than in carcinomas. It differs from case to case, but in the same case the higher degree of dysplasia possesses higher proliferative activity. Dysplasia is associated with abnormal proliferation pattern. Special attention should be paid to those with abnormal proliferation patterns as well as high proliferative activity. PCNA immunostaining is of some referential value in predicting clinical outcome and guiding to make an early diagnosis of malignancy.

Synchronous Comparative Evaluation of Fibronectin Continuity and Cellular Growth Kinetics in Malignant Cutaneous Melanoma

Cellular fibronectin mediates the adhesion of cells with the extracellular matrix and thus probably regulates tumor invasion. Evaluation of proliferating cell nuclear antigen expression and counting of silver nuclear organizer regions potentially assess proliferative fraction and biologic aggressiveness in several malignancies. We investigated the above markers’ prognostic value in 60 malignant melanomas of the skin. Deep Clark levels were statistically associated with discontinuous fibronectin staining pattern (SPII) ( P &lt; .05) as well as with high proliferating cell nuclear antigen and silver nuclear organizer regions indexes ( P &lt; .01 and P &lt; .05, respectively). Fibronectin staining pattern (SPII) was frequently observed in thick melanomas ( P &lt; .05). High proliferating cell nuclear antigen immunoreactivity positively correlated with mitotic activity ( P &lt; .05), the presence of vertical growth phase ( P &lt; .05), and increased silver nuclear organizer regions counts ( P &lt; .05). Patients with continuous fibronectin staining pattern (SPI) and low proliferating cell nuclear antigen scores were unlikely to develop metastatic disease ( P &lt; .01). Therefore, the simultaneous comparative assessment of these factors is very promising in predicting melanomas clinical evolution.

Vimentin and proliferating cell nuclear antigen (PCNA) expression in node-negative breast carcinomas and their correlations with pathologic variables and prognosis

Abstract Vimentin and proliferating cell nuclear antigen (PCNA) immunohistochemical staining was performed in a series of 92 node-negative breast carcinomas and expression compared with tumour size, histological grade, nuclear grade, necrosis, lymphocytic infiltrate, oestrogen and progesterone receptors, and relapse rate. Vimentin was expressed in 13% of tumours and all positive cases were invasive ductal carcinomas. A strong relationship was noted between vimentin positivity, and both histological ( P = 0.01) and nuclear grade ( P = 0.02). The percentage of PCNA positive cells (PCNA index) varied from 0.2 to 70% (mean 27.45, median 28). PCNA index showed a significant correlation with histological ( P = 0.001) and nuclear grade ( P = 0.004). Furthermore vimentin positivity was significantly associated with high PCNA index ( P = 0.002). With univariate analysis vimentin positivity and high PCNA index (> 28) were both significantly correlated with shorter disease free survival ( P = 0.003 and P = 0.002 respectively) (median follow-up 84 months), while no other parameter reached significance. Using multivariate analysis PCNA index was statistically related to disease-free survival ( P = 0.05), whereas vimentin lost its significance. Our results suggest that PCNA may be useful in identifying node-negative breast cancer patients at risk of recurrence.

Tumour angiogenesis and tumour cell proliferation as prognostic indicators in gastric carcinoma

Tumour growth depends on neovascularisation and tumour cell proliferation. Factor VIII-related antigen (F-VIII RA) localises to vascular endothelium. Expression of proliferating cell nuclear antigen (PCNA) is correlated with cell proliferation. We investigated the correlation between the expression of these antigens and prognosis in gastric carcinoma. A total of 108 specimens resected from patients with gastric carcinoma were investigated by staining with monoclonal antibodies against F-VIII RA and PCNA. Microvessel count (MVC; the mean number of microvessels in the five areas of highest vascular density at 200 x magnification) and PCNA labelling index (PCNA LI; percentage of positive cells in more than 500 tumour cells) were determined. The results showed that prognosis was significantly worse in patients who had a tumour with a high MVC (16 or greater) or a high PCNA LI (42% or greater) than in those patients who had a tumour with a low MVC (less than 16) or a low PCNA LI (less than 42%). Furthermore, MVC was significantly associated with the risk of hepatic recurrence. In conclusion, both MVC and PCNA LI may be good prognostic indicators in patients with gastric carcinoma.

Prognostic Value of Proliferating Cell Nuclear Antigen (PCNA) Immunostaining in Neuroblastoma

Immunostaining for proliferating cell nuclear antigen (PCNA), a marker of cell proliferation, is being increasingly used to study the proliferative activity of tumors, and the PCNA labeling index has been correlated with the prognosis of several malignant neoplasms. Formalin-fixed, paraffin-embedded tissue specimens of 24 primary neuroblastomas were immunostained using an anti-PCNA monoclonal antibody and the PCNA index was calculated. Then the relationship between the PCNA index, prognosis, and various other factors was assessed, retrospectively. The mean PCNA index was 11.0%. Patients having tumors with a high PCNA index (> or = 11.0%) showed a significantly lower survival rate than those possessing tumors with a low PCNA index (P < 0.001). Moreover, the tumors showing N-myc amplification had a high mean PCNA index of 15.6%, while those without N-myc amplification had a low mean index of 1.7% (P < 0.01). The PCNA index was closely related to the prognosis of neuroblastoma and to N-myc amplification. It has the potential to be a useful prognostic indicator of the patients with neuroblastoma.

EXPRESSION OF EPIDERMAL GROWTH-FACTOR (EGF), MATRIX METALLOPROTEINASE-9 (MMP-9) AND PROLIFERATING CELL NUCLEAR ANTIGEN (PCNA) IN ESOPHAGEAL CANCER

Expression of human epidermal growth factor (EGF) and matrix metalloproteinase-9 (MMP-9/gelatinase B) was examined immunohistochemically in 62 cases of surgically resected esophageal carcinomas, and the correlation between EGF expression and the proliferative activity of the tumors was studied by analysing the number of proliferating cell nuclear antigen (PCNA)-positive cells. Expression of EGF and MMP-9 was observed in 16 (38.1%) and 18 (42.9%) of the 42 superficial carcinomas and 8 (40%) and 14 (70%) of the 20 advanced carcinomas, respectively. The differences in the MMP-9 expression between the superficial carcinomas and the advanced carcinomas was significant (p<0.05). The synchronous expression of EGF and MMP-9 was observed in 15 (24.2%) of 62 carcinomas, i.e. 62.5% of the 24 EGF-positive tumors expressed MMP-9, but there was no statistically significant correlation between the expression of EGF and MMP-9. The relationships between EGF expression and tumor proliferative activity and prognostic factors were investigated. The PCNA grades were significantly higher in tumors with EGF-positive than those with EGF-negative expression (p<0.05) and the EGF expression showed a good correlation between the expression of MMP-9 and vascular invasion (p<0.01). The expression of MMP-9 was stronger in the advanced than the superficial carcinomas and there was a good correlation with vascular invasion (p<0.01). In a follow-up study of 55 patients, those with tumor that expressed MMP-9 or had a high PCNA grade showed a poor prognosis. Taken together, these observations suggest that both EGF and MMP-9 participate in the invasive phenotype in human esophageal carcinoma, but the expression of EGF is not directly related to the expression of MMP-9. Additional growth factors and cytokines may be involved in regulation of MMP-9 expression in this carcinoma.

An immunohistochemical study of p53 with correlations to histopathological parameters, c- erbB-2, proliferating cell nuclear antigen, and prognosis

In an immunohistochemical study of 490 primary breast cancer patients with a follow-up period of more than 10 years, we found that p53 was not a prognostic factor for disease-free or overall survival among the whole cohort or among lymph node-positive or -negative patients. In a multiple logistic regression model classical histopathological parameters, such as lymph node status, number of mitoses, histological grade, and absence of progesterone receptors, were independent, poor prognostic predictors. In univariate analysis p53 immunoreactivity was positively correlated with the absence of tubule formation, high histological grade (poor differentiation), absence of estrogen receptors (ER), and a high proliferating cell nuclear antigen (PCNA) score (ie, parameters indicative of an aggressive phenotype). The lack of prognostic significance may be attributable partly to the method used, because immunohistochemistry underdetects rather than overdetects p53 protein. No correlation between p53 and c-erbB2-oncoprotein was demonstrated.

Risk factors for intrahepatic recurrence in human small hepatocellular carcinoma

Background/Aims : Postoperative intrahepatic recurrence of human hepatocellular carcinoma is high. Recently, the relationship between proliferating cell activity in the cirrhotic liver and occurrence or recurrence of hepatocellular carcinoma has been reported. Methods : One hundred two resected cases of small hepatocellular carcinoma of <3 cm in diameter without venous invasion or intrahepatic metastasis were examined to ascertain the factors affecting postoperative intrahepatic recurrence. Results : Cumulative intrahepatic recurrence rates at 1, 3, and 5 years after surgery were 12.0%, 57.2%, and 67.6%, respectively. The log-rank test indicated that serum albumin levels of <3.7 g/dL, alanine aminotransferase levels of more than 54 IU/L, active inflammation in the nontumorous portion, and high proliferating cell nuclear antigen labeling index in the nontumorous portion (>23.2%) were significant risk factors for recurrence. Tumor factors, including tumor size, histological grade, or α-fetoprotein level, were not significant risk factors. Cox's proportional hazard model identified that serum albumin level and alanine aminotransferase level were independently associated with intrahepatic recurrence after hepatectomy. Conclusions : This study suggests that the principal cause linked to either a recurrence or a second new growth of hepatocellular carcinoma in the remnant liver after hepatectomy was the state of the underlying liver parenchyma as well as other tumor factors per se.

Quantitative expression of proliferating cell nuclear antigen by western blot (PCNAWB) in peripheral blasts correlates with remission induction in patients with acute myelogenous leukemia.

Proliferating cell nuclear antigen (PCNA) is a 36-kD nuclear protein that functions as a cofactor of delta DNA polymerase which is regulated in a cell cycle-dependent fashion. PCNA expression also increases when cells are actively engaged in DNA repair. We used Western blotting (WB) to measure the level of expression of PCNA in peripheral blasts of 36 adult acute myelogenous leukemia (AML) patients treated with Ara-C based induction regimens. PCNA levels correlated positively with the percentage of cells in S+G2M of the cell cycle. Logistic regression analysis revealed PCNA (beta = 4.5162; p = 0.0260) together with age (beta = 0.1777; p = 0.0364) as independent variables for remission induction: high PCNA levels were associated with poor response to induction therapy. PCNA expression was not, however, a predictor of survival in this subset of patients. We conclude that PCNA levels in this disease may be important for predicting response to Ara-C based remission induction chemotherapy.

PCNA immunostaining combined with AgNOR staining in esophageal squamous cell carcinoma to identify patients with a poor prognosis

Immunostaining of the proliferating cell nuclear antigen (PCNA) provides important information about cell kinetics and is easily performed on routinely obtained formalin-fixed, paraffin-embedded materials. We report herein the results of a retrospective study on PCNA staining in esophageal cancer undertaken to determine its significance. As this study indicated that immunoreactivity was preserved in specimens fixed within 24h, only 31 specimens from surgical patients were available for this investigation. The mean PCNA index of the patients without invasion to the adventitia (35.7 +/- 17.9) was significantly lower than that of those with invasion to the adventitia or neighboring structures (49.7 +/- 14.5), while the PCNA index did not correlate with other clinicopathologic parameters such as histologic type, lymph node metastases, or prognosis. However, when an analysis of PCNA staining was combined with an analysis of argyrophilic nucleolar organizer region (AgNOR) staining, a correlation with prognosis was found. In fact, seven patients with a high PCNA index (> or = 44) and AgNOR count (> or = 6) had a significantly poorer prognosis than the remaining 22 (P = 0.0014), and six of these seven patients died within 2 years. These results indicate that this combined evaluation may be useful for the identification of patients with a poor prognosis among those undergoing surgery for esophageal squamous cell carcinoma.

Expression of p53 protein, PCNA, and Ki-67 in osteosarcomas of bone.

Expressions of p53 protein, a product of the tumor suppressor gene were studied in osteosarcomas relating to various prognostic factors. Thirty-four osteosarcomas were investigated immunohistochemically with a monoclonal antibody clone PAb240, which recognizes a common conformational epitope of mutant p53 proteins and another clone PAb1801, which reacts with both wild- and mutant-type p53 proteins. The results were compared with expressions of proliferating cell nuclear antigen (PCNA) and Ki-67 providing a simple method for the assessment of growth fractions of tumors. PAb240 stained nuclei and cytoplasm of tumor cells in 8 of 34 osteosarcomas (23.5%), whereas PAb1801 reacted in all 34 osteosarcomas (100%). Fifteen tumors (44.1%) showed positivity for PAb1801 in more than half of the tumor cells. Twelve patients were alive and thirteen were dead. Tumors from 9 patients (75%) who survived revealed only focal positive immunoreactions with PAb1801 and tumors from 6 patients (46.1%) who died revealed diffuse reactions. Twelve cases (35.3%) showed a high PCNA index (> 40%) and fibroblastic osteosarcomas revealed the highest PCNA positivity. Twenty-two cases (64.7%) revealed a very low Ki-67 index (less than 10%) and Ki-67 index showed a good correlation with PCNA positivity (r = 0.6247). Expressions of both wild-and mutant-type p53 protein, PCNA, and Ki-67 were not correlated with other clinical or pathological parameters.

Correlation between immunohistochemical expression of proliferating cell nuclear antigen and flow cytometry parameters in colorectal neoplasia

Proliferating cell nuclear antigen immunohistochemical expression and flow cytometry techniques were used in this study to estimate the proliferation tendency and biologic aggressiveness in benign and malignant epithelial tumors of the colon and rectum. Thirty-five adenomas and 60 adenocarcinomas were studied immunohistochemically concerning proliferating cell nuclear antigen positivity in tumor cell nuclei. In addition, flow cytometry techniques were used to estimate the DNA content and percentage of tumor cells in the S-phase. The mean proliferating cell nuclear antigen score for adenomas was 38 percent compared with a mean score of 50.4 percent for adenocarcinomas that were studied (P < 0.05). In dysplastic areas of malignantly transformed adenomas (n = 5), the highest proliferating cell nuclear antigen score (80 percent) was focally observed. Taking flow cytometry parameters into account, we found out that proliferating cell nuclear antigen can be used as an indirect indicator of the number of cells in the S-phase (SPF) but not as an independent prognostic factor. Statistical significance was found between Type III (aneuploid carcinomas) and increased proliferating cell nuclear antigen expression (proliferating cell nuclear antigen score > or = 60 percent). Furthermore, aneuploidy was especially found on cancer located on the left colon (44 percent vs. 14 percent of right colon neoplasms). Considering DNA ploidy of the above neoplasms, the aneuploid adenocarcinomas had a tendency for poorer prognosis especially if they were related to Dukes Stage C female patients. The comparative assessment of the above parameters might be of considerable importance in the study of the proliferation activity of any form of colorectal neoplasia.

Prognostic Value of Proliferating Cell Nuclear Antigen in Phyllodes Tumor of the Breast

The proliferating cell nuclear antigen (PCNA), a nuclear protein essential for cellular DNA synthesis, has been used to assess cellular proliferation in many tumors. To evaluate the potential value of PCNA in predicting the outcome of phyllodes tumor of the breast, we retrospectively studied 17 tumors diagnosed during the period 1985-1991. PC 10, a monoclonal antibody that recognizes PCNA, was applied to for malin-fixed, paraffin-embedded sections. The PCNA index ranged from 0.2% to 66.3%. The tumors were stratified into high (&gt;9.8%, n = 4) or low (≤9.8%, n = 13) PCNA index groups. No significant correlation between high PCNA index and the clinicopath ologic parameters with the exception of infiltrative margin was sound. However, the difference in recurrence-free survival between the two groups was significant (log rank test P &lt; .01). The Cox's regression analysis showed that high PCNA index was an important prognostic factor for tumor recurrence. PCNA staining could be used as an objective prognostic factor for the local recurrence of phyllodes tumor of the breast. Int J Surg Pathol 2(2):125-132, 1994

Human non‐small cell lung cancer: P53 protein accumulation is an early event and persists during metastatic progression

Mutations in the p53 tumour suppressor gene, with consequent accumulation of the p53 protein, are frequently observed in non-small cell lung cancer (NSCLC). Little is known, however, about the timing of their appearance or their maintenance through cancer progression and metastatic spread. We have examined the normal epithelium and a panel of bronchial lesions, including dysplastic, neoplastic, and metastatic lesions, for p53 immunoreactivity and for expression of proliferating cell nuclear antigen (PCNA). No p53 immunoreactivity was found in normal and hyperplastic epithelium, nor in squamous metaplastic lesions. Twenty out of 30 invasive tumours and 13 out of 17 in situ carcinomas adjacent to an invasive tumour showed p53 immunoreactivity. There was a strict correlation between the level of p53 expression in the non-invasive and the invasive components of the tumours. Five out of eight pairs of primary tumours and matching metastases expressed p53, at identical levels in both compartments. These data indicate that p53 overexpression can occur in the earliest recognized phase of NSCLC and that the alteration is maintained during progression from in situ to invasive carcinoma and metastatic spread. PCNA expression increased from early to advanced phases of NSCLC. High PCNA immunoreactivity was observed in tumours expressing high p53 levels. A significant association was observed for PCNA expression between preinvasive and invasive lesions.

Proliferating cell nuclear antigen labeling index of preoperative biopsy specimens in gastric carcinoma with special reference to prognosis.

Proliferating cell nuclear antigen (PCNA) is an auxiliary protein of DNA polymerase delta and is considered to correlate with the cell's proliferative state. Immunohistochemical methods with a anti-PCNA antibody (PC10) have particular advantages compared with other techniques because of the maintenance of the tissue architecture and simplicity of the methodology. The authors investigated the correlation between the tumor's proliferative activity and progression of gastric carcinoma using immunohistochemical staining with PC10. One hundred eighty-nine endoscopic biopsy specimens from patients with gastric carcinoma before operation were investigated by immunohistochemical study, using anti-PCNA monoclonal antibody (PC10). The correlation of PCNA labeling index (percentage of positive cells in more than 500 tumor cells) with various clinicopathologic factors and prognosis was studied. The PCNA labeling index became higher as the histologic stage increased. In patients with lymph node metastasis, vascular invasion, liver metastasis, and peritoneal metastasis, the labeling index was significantly higher. In patients with high PCNA labeling index (50% or greater), prognosis was significantly poorer than in those with a low index (less than 50%). The rate of disease recurrence after curative resection was significantly higher in patients with high PCNA grade group. As a result of this study, PCNA labeling index is suggested to be correlated with the depth of invasion, organ metastasis, vascular invasion, and tumor stage and to be effective as a prognostic factor.

Proliferating cell nuclear antigen in breast carcinomas

Proliferating cell nuclear antigen (PCNA), was examined by immunohistochemistry in 509 breast carcinomas. The immunoreactivity was found to be independent of the length of fixation when the tissue sections were microwaved before incubation with the primary antibody. The PCNA immunoreactivity was assessed by two semi-quantitative methods, which were correlated but not exchangeable. The comedo type of intraductal carcinomas and invasive ductal carcinomas had a higher PCNA score than other types. Lymph node metastases had a significantly higher PCNA score than primary carcinomas. High PCNA immunoreactivity was correlated with the presence of lymph node metastases, absence of tubule formation, numerous mitoses, severe nuclear pleomorphism, high histological grade and absence of progesterone receptors (PgR). PCNA in lymph node positive tumours was correlated with tumour type, especially with ductal carcinomas, absence of tubule formation, high histological grade and absence of PgR, whereas PCNA in lymph node negative tumours was correlated with large tumour size, numerous mitoses, severe nuclear pleomorphism and high histological grade. Number of mitoses and nuclear pleomorphism were the two most important factors in predicting the PCNA score; the absence of PgR and nuclear pleomorphism were important in lymph node negative and positive tumours, respectively. In a univariate analysis high PCNA score was found to be correlated with shorter relapse-free period and poorer over-all survival.