Nuclear P53 Staining Research Articles

Histopathological Features and p53 Nuclear Protein Staining as Predictors of Survival and Tumor Recurrence in Patients with Transitional Cell Carcinoma of Renal Pelvis

Histopathological Features and p53 Nuclear Protein Staining as Predictors of Survival and Tumor Recurrence in Patients with Transitional Cell Carcinoma of Renal Pelvis

Histopathological Features and p53 Nuclear Protein Staining as Predictors of Survival and Tumor Recurrence in Patients with Transitional Cell Carcinoma of Renal Pelvis

Purpose We determine which histopathological features are predictive of recurrence and cause-specific survival in renal pelvic transitional cell carcinoma. Materials and Methods Univariant and multivariant analysis was done on material from 67 patients. Results Univariate and multivariate analysis identified lamina propria invasion, grade 3 tumors and capillary-lymphatic invasion as predictors of disease-specific survival. Multicentric disease was the sole independent predictor of recurrence. Multicentric disease and lamina propria invasion were independent predictors of recurrence-free survival. Also, p53 over-expression was not statistically associated with any of the studied prognostic factors. Conclusions Histopathological features remain the cornerstone of prognostic assessment for renal pelvic transitional cell carcinoma.

Human bladder carcinoma cell lines as indicators of oncogenic change relevant to urothelial neoplastic progression.

Analysis of human tumour-derived cell lines has previously resulted in the identification of novel transformation-related elements and provided a useful tool for functional studies of different genes. To establish the utility of such cell lines as indicators of change relevant to urothelial cancer, we have characterised the expression of five genes (p53, MDM2, Rb, E-cadherin, APC) within a panel of human bladder carcinoma cell lines. Using single-strand conformation polymorphism (SSCP) and direct sequencing, p53 mutations were identified in 7/15 (47%) cell lines reflecting events reported in bladder tumours. Immunohistochemical analysis of p53 in cultured cells and in paraffin-embedded sections of xenografts from the cell line panel revealed discordant results. An absence of p53 nuclear staining was associated with an exon 5 mutation in EJ and with multiple p53 mutations found in J82. Two cell lines positive for p53 staining in the absence of detectable mutation displayed overexpression of MDM2 (PSI, HT1197) in Western blot analysis. Loss or aberrant Rb expression was recorded in 5/15 (TCCSUP, SCaBER, 5637, HT1376, J82) cell lines. Absence of E-cadherin was recorded in 5/15 cell lines (TCCSUP, EJ, KK47, UM-UC-3, J82) with loss of alpha-catenin in immunoprecipitated E-cadherin complexes of CUBIII. Western blot analysis of APC revealed a truncated protein in 1/15 (CUBIII) cell lines. The characterisation of oncogenic events within this panel of human bladder carcinoma cell lines establishes a representation of change observed in bladder tumours and better defines the genotypic background in these experimental human cell models of neoplastic progression.

Detection of TP53 gene mutation in human meningiomas: a study using immunohistochemistry, polymerase chain reaction/single-strand conformation polymorphism and DNA sequencing techniques on paraffin-embedded samples.

Mutations in the TP53 tumor suppressor gene have been studied in different types of brain tumors. Little is known about this genetic event in human meningioma, a mostly benign tumor. To investigate the frequency of TP53 gene mutations in human tumors derived from meningeal tissues, paraffin-embedded tissues from 30 cases (including 2 malignant and 4 atypical meningiomas, as well as 2 hemangioblastomas and 3 hemangiopericytomas) were screened by immunohistochemistry. Polymerase chain reaction/single strand conformational polymorphism (PCR/SSCP) and direct DNA sequencing were thereafter performed in selected cases. Nuclear p53 staining was not seen in any of the 19 benign meningiomas tested, while atypical meningiomas, hemangioblastomas, and hemangiopericytomas displayed nuclear staining in a subpopulation of tumor cells in 4 out of 5, 2 out of 2, and 3 out of 3 cases, respectively. One malignant meningioma showed an intense nuclear staining and a band shift in SSCP. In this case, we identified a mutation in the TP53 gene at codon 161 changing GCC to ACC and resulting in an alteration of alanine to threonine in this position. Our results indicate that TP53 gene mutation may be considered as a marker for malignant transformation in meningioma. p53 immunoreactivity, even in the absence of detectable gene mutation, is also associated with atypia and does not appear in regular benign meningiomas.

Immunohistochemical and molecular analysis of p53, MDM2, proliferating cell nuclear antigen and Ki67 in benign and malignant peripheral nerve sheath tumours.

A series of 26 malignant peripheral nerve sheath tumours (MPNST) and 24 benign peripheral nerve sheath tumours (BPNST) were analysed immunocytochemically for p53 expression and the cell proliferation markers proliferating cell nuclear antigen (PCNA) and Ki67 (with MIB1). In 23/26 MPNST, 5%-65% of the tumour cell nuclei were immunoreactive for Ki67 with MIB1 while none of the 24 BPNST had nuclear staining exceeding 5%. Greater than 50% nuclear PCNA staining was detected in 25/26 MPNST compared with 8/24 BPNST; 17/26 MPNST showed 5-100% nuclear staining for p53 (13/26 > 20%), whereas none of the BPNST had nuclear staining exceeding 1%. The Ki67, PCNA and p53 immunostaining results correlated significantly with benign versus malignant (P < 0.001, P < 0.001 and P < 0.005, respectively) as well as mitotic rate (P < 0.001, P < 0.05 and P < 0.05). Ki67 immunostaining results correlated significantly with PCNA and p53, as did p53 and Ki67 and PCNA (P < 0.001 in both). Stepwise (logistic regression forward) multivariate analysis of the variable, benign versus malignant, revealed the strongest correlations with PCNA (P = 0.007) and Ki67 (P = 0.021). Direct confirmation of the presence of p53 protein was obtained by western blot analysis of 3 MPNST and 5 BPNST. Two MPNST, showing 90% and 30% immunoreactivity, were positive for p53, while one MPNST with 5% immunoreactivity and all 5 BPNST were negative. Southern blot analysis performed on the two MPNST with high p53 protein levels revealed no amplification of the MDM2 gene, suggesting that high p53 levels in MPNST are likely to be due to mutation. The results also indicate that PCNA and Ki67 are potentially useful in distinguishing BPNST from MPNST, particularly in problematic cases of cellular schwannoma versus MPNST. The detection of p53 in a large percentage of cells of a plexiform neurofibroma giving rise to MPNST and Ki67 in 5% and 25% of cells of two similar cases suggests that malignant transformation may be detected in some cases by p53 and proliferation markers prior to overt histological evidence of malignancy.

Aberrant p53 expression does not correlate with the prognosis in anaplastic astrocytoma.

Mutations of the p53 tumor-suppressor gene, as determined by the immunohistochemistry of archival formalin-fixed specimens, have been correlated with the prognosis for patients with many different types of malignancy. Similar correlations have been shown in series including patients with all grades of astrocytoma. We hypothesized that this might be a clinically useful prognostic indicator for patients with a defined grade of astrocytoma, anaplastic astrocytoma. This series comprised 54 consecutive patients with biopsy-proven anaplastic astrocytoma treated at one institution. When the CM-1 antiserum was used for testing, 33 (61%) of the 54 biopsies exhibited positive nuclear staining for p53, indicating an abnormal accumulation of the protein. This staining was graded according to the number of positive cells per high-power field. Positive immunohistochemical staining for p53 in the tumor cell nuclei did not correlate with the patient's outcome. Significant correlates of improved patient survival were the presentation with epilepsy in the absence of a neurological deficit (P = 0.005) and the surgeon's performance of a macroscopically complete surgical resection of the tumor (P = 0.01).

P53 expression in dedifferentiated chondrosarcoma

p53 acts as a tumor suppressor gene because of to its negative control of the cell cycle and its central role in programmed cell death. It frequently is mutated, as observed in a variety of human neoplasms. The mutations inhibit tumor-suppressor activities of p53, which may gain a new function of tumor promotion. In this study, p53 was investigated in various components of dedifferentiated chondrosarcoma and correlated with their proliferative activities. Immunohistochemical assays for p53, Ki-67, and proliferating cell nuclear antigen (PCNA) were used in a series of eight dedifferentiated chondrosarcomas of bone. The cartilaginous component was low grade (Grade I-II) in five cases. It was predominantly low grade with foci of a high grade (Grade III) chondrosarcoma in the remaining three cases. The noncartilaginous (dedifferentiated) high grade component consisted of malignant fibrous histiocytoma in five cases and osteosarcoma in three. Regardless of the histological type, diffuse strong nuclear staining for p53 occurred in the high grade noncartilaginous component of all eight of the tumors. The low grade cartilaginous component of six cases was negative for p53, with focal weak staining in the two remaining cases. The high grade cartilaginous component showed strong positive staining for this protein in all three cases. Ki-67 and PCNA expression were similar to that of p53. The percentage of p53 positive staining roughly was parallel to the proliferating fraction of cells in various components of dedifferentiated chondrosarcoma. Moreover, p53 overexpression was consistently present in the high grade noncartilaginous (dedifferentiated) component of the tumor and was accompanied by increased proliferative activity.

Immunohistochemical detection of p53 protein is not associated with a poor prognosis in non-small-cell lung cancer

Immunohistochemical detection of the p53 gene product by monoclonal antibodies has been shown to be associated with a poor clinical outcome in carcinomas of the breast and stomach. Because the prognostic relevance of p53 immunostaining in lung cancer is still under debate, we studied the expression pattern and clinical significance of such staining in 73 patients with operable non-small-cell lung cancer. p53 expression was detected on frozen sections with the use of monoclonal antibody p1801, which recognizes both the wild-type and mutant gene product (alkaline phosphatase-anti-alkaline phosphatase method). A tumor was considered p53 positive if more than 1% of the tumor cells were stained. The p53 expression pattern was compared with clinicopathologic parameters, and analysis of follow-up, based on the data of 65 patients, was done by a log rank test (median observation time, 780 days). Nuclear p53 staining was detected in 33 of 73 non-small-cell lung cancers (45.2%). Comparison with clinicopathologic parameters demonstrated that the p53 protein was detected more frequently in younger patients (younger than 50 years, p = 0.014), whereas no correlation was found with sex, tumor differentiation, tumor histologic type, or TNM stage. Surprisingly, follow-up analysis revealed that p53 staining was associated with an increased rate of disease-free survival, especially in patients with early stage tumor disease ( p = 0.004) and in male patients ( p = 0.023). Counter to previous studies in other solid tumors, immunocytochemical detection of p53 expression does not predict a poor clinical outcome in non-small-cell lung cancer. In early-stage lung cancer it might be associated with an improved disease-free survival, which suggests that the majority of the detected protein inherits the wild-type tumor suppressor function. (J T HORAC C ARDIOVASC S URG 1995;109:1205-11)

Amplification of the MDM2 gene in human breast cancer and its association with MDM2 and p53 protein status.

The present study reports on the frequency of MDM2 gene amplification and MDM2 protein expression in a series of 100 breast carcinomas and its association with accumulation of the p53 protein. Of the 100 cases, frozen samples for 82 cases were available for Southern blotting. Three of the 82 (4%) demonstrated MDM2 gene amplification of up to 6-fold. Immunohistochemical analysis of the formalin-fixed, paraffin-embedded tumours demonstrated that 7/97 (7%) had nuclear expression for MDM2 in 10-50% of the tumour cells (type 2 staining) and were denoted MDM2+. Two of the MDM2-amplified samples were MDM2+ with one of the two tumours also displaying type 2 p53 nuclear staining. Finally at the protein level, MDM2+ tumours were significantly associated with tumours having low levels of p53 staining (0-10% cells positive) (P = 0.03). We conclude that MDM2 gene amplification occurs at a lower frequency in breast cancer than in non-epithelial tumours. Alterations in MDM2 and p53 may represent alternative pathways in tumorigenesis, but they are not mutually exclusive in all cases.

Site-specific comparison of p53 immunostaining in squamous cell carcinomas

The p53 tumor suppressor gene is believed to be the most commonly mutated gene in human cancer. p53 is thought to function as a negative regulator of the cell cycle, arresting cells in the G1 phase. This study examined the effects of different mutagenic environments on the incidence of p53 overexpression in squamous cell carcinomas (SCCs) from sun exposed and non-sun exposed squamous epithelium. An immunohistochemical analysis was undertaken in an attempt to assay SSC for p53 overexpression, an indirect measure of missense mutant p53. Positive nuclear staining for p53 was observed in 14 of 21 sun exposed SCCs, two of 19 vulvar/perianal SCCs, and 15 of 20 oral cavity SCCs. The number of positive anogenital tumors was low compared with that of both sun exposed (chi-squared, 1 df, P = .0004) and oral (chi-squared, 1 df, P < .0001) sites. It was concluded that p53 protein accumulation is common in sun-exposed cutaneous SCC and oral SCC compared with anogenital SCC, and thus it is hypothesized that the nature of the mutagenic environment in which SCC develops directly affects the incidence of immunohistochemically detectable p53-positive cells.

High prevalence of expression of p53 oncoprotein in oral carcinomas from India associated with betel and tobacco chewing.

A recent study reported a low prevalence of p53 expression (11%) in oral squamous cell carcinomas (SCCs) from South Asia, in contrast to a high prevalence (averaging 52%) in other studies. It was proposed that the different aetiologies for oral SCCs in the South Asia population, i.e. betel and tobacco chewing in combination with smoking and alcohol consumption as compared to smoking and alcohol consumption alone in other populations, may account for the low prevalence of p53 expression. To confirm this hypothesis, we examined p53 expression immunohistochemically in 23 cases of oral SCC from patients in Southern India. Thirteen of the 23 SCCs (56.5%) demonstrated nuclear p53 staining. The expression of p53 was strongly correlated with the number of tobacco-containing quids chewed per day (r = 0.8). These data support the hypothesis that carcinogens derived from tobacco and betel chewing may induce p53 mutations, which in turn are involved in the development of oral cancer.

P53 expression in multicentric squamous cell carcinoma and surrounding squamous epithelium of the upper aerodigestive tract. Immunohistochemical analysis of 95 lesions.

It is now well documented that patients with squamous cell carcinoma of the upper aerodigestive tract frequently develop additional squamous cell carcinoma in the same field. p53 expression in 95 patients with multicentric squamous cell carcinoma and in squamous epithelia surrounding multicentric squamous cell carcinomas of the upper aerodigestive tract in 20 patients was examined by immunohistochemistry. In addition, p53 expression in 129 patients with supposedly unicentric squamous cell carcinoma and in squamous epithelia surrounding unicentric squamous cell carcinoma in 22 patients was also examined by immunohistochemistry. Among the 95 patients with multicentric squamous cell carcinoma, 62 (65%) had a clearly positive reaction for p53 protein, whereas 56 (43%) of 129 patients with unicentric squamous cell carcinoma had a positive reaction for p53 protein. The frequency of positive nuclear p53 staining in multicentric squamous cell carcinoma appeared higher than that in unicentric squamous cell carcinoma. However, there was no significant difference between the two groups. Among the nondysplastic squamous epithelia surrounding multicentric squamous cell carcinomas in 20 patients, 12 (60%) were p53 positive, whereas only five (22%) of 22 patients with nondysplastic squamous epithelia surrounding unicentric squamous cell carcinomas were positive. The difference between the two groups was significant (P < 0.05). The present results suggest that nuclear accumulation of p53 in the squamous epithelium surrounding multicentric squamous cell carcinoma is probably due to heavier exposure and increased susceptibility to mutagens of the affected individuals, although this remains to be verified.

P53 expression in hepatocellular carcinoma in a population in Singapore with endemic hepatitis B virus infection.

To study the expression and clinical significance (if any) of p53 protein in hepatocellular carcinomas (HCC) arising in a population with endemic hepatitis B virus (HBV) infection. Immunohistochemical staining was performed on formalin fixed, paraffin was embedded histological sections of 46 HCC cases using an antihuman p53 monoclonal antibody; serial sections were also stained for hepatitis B surface antigen (HBsAg), hepatitis B core antigen (HBcAg) and alpha fetoprotein (AFP). Nuclear p53 staining was assessed according to intensity (absent, weak or strong) and extent (< 5%, 6-25%, 26-50%, and > 50%) of positive cells. Tissue HBsAg, HBcAg and AFP were recorded as absent or present. The p53 protein was expressed in 35% (16 of 46) of HCCs; the positive rate in grade III/IV tumours (13 of 31; 42%) was higher than in grade I/II tumours (three of 15; 20%) but this was not statistically significant. HBsAg positive tumours showed almost the same proportion of p53 staining (11 of 29; 38%) as HBsAg negative ones (five of 17; 29%). The p53 protein was expressed in 35% of HCC cases. There was no statistically significant correlation between HBV infection and p53 protein expression. Similarly, there was no definite correlation between p53 positivity and tumour size, histological grade or vascular invasion.

Frequency and characterization of p53 mutations in clinically localized prostate cancer

Objectives To determine the frequency of abnormal p53 expression and to characterize confirmed p53 mutations in tumors from patients with clinically localized adenocarcinoma of the prostate. Methods p53 protein nuclear accumulation was determined immunohistochemically in the initial diagnostic tumor specimens from 37 patients with clinically localized prostate carcinoma. Two primary antibodies were used on all specimens. Structural analysis of the p53 gene was performed using the methods of polymerase chain reaction (PCR)/single-strand conformation polymorphism (SSCP) and DNA sequencing. Results In 1 of the 37 (2.7%) tumor specimens, intense p53 nuclear staining was demonstrated using either antibody PAb 1801 or CM-1. The staining in this case was heterogeneous, with approximately 40% of tumor nuclei staining for p53. This tumor specimen was microdissected and DNA was extracted. Following PCR amplification, abnormally migrating bands were noted on SSCP analysis of exon 8. DNA sequencing confirmed the mutation as a C → A transversion in codon 281 (asp → glu). PCR/SSCP analysis of exons 5 through 8 was also performed for seven additional tumors that were negative for p53 nuclear accumulation by immunohistochemical (IHC) methods. All of these specimens demonstrated wild-type p53. Conclusions The results of this study confirm and extend our previous findings that p53 mutations are rare in clinically localized adenocarcinoma of the prostate. In detecting clonal p53 mutations, standard immunohistochemical technique correlates reliably with structural p53 gene analysis of the evolutionary conserved domains encompassing exons 5–8. Importantly, most reports have demonstrated that p53 mutations detected by IHC are a late step in the progression of prostate cancer and are associated with advanced disease, dedifferentiation, and the acquisition of androgen independence.

Accumulation of p53 protein in normal, dysplastic, and neoplastic Barrett's oesophagus.

Accumulation of p53 protein was determined by immunohistochemistry in archival material of biopsy specimens from 102 patients with Barrett's oesophagus with different grades of dysplasia, in 24 oesophageal adenocarcinomas associated with Barrett's oesophagus, and in 23 cases of metaplastic epithelium adjacent to these carcinomas. Immunostaining for the p53 protein was found in 23/102 (23 per cent) cases of the Barrett's oesophagus biopsies and in 12/23 (52 per cent) cases of Barrett's oesophagus adjacent to adenocarcinoma. Significant correlations were found between the grade of dysplasia and p53 immunoreactivity in both Barrett's biopsies without adenocarcinoma (P < 0.001) and Barrett's oesophagus adjacent to adenocarcinoma (P < 0.05). In the adenocarcinomas, intense nuclear immunohistochemical staining for p53 was diffusely or focally present in 20/24 (83 per cent) of the specimens. In Barrett's oesophagus, p53 is a progression marker with high expression in high-grade dysplasia (89 per cent) and adenocarcinoma (83 per cent).

Value of P-glycoprotein, glutathione S-transferase pi, c-erbB-2, and p53 as prognostic factors in ovarian carcinomas.

To determine the prognostic value of immunostaining of P-glycoprotein (P-gp), glutathione S-transferase (GST) pi, c-erbB-2, and p53 in patients with advanced-stage ovarian carcinoma. Immunostaining of P-gp, GST pi, c-erbB-2, and p53 was performed on 89 primary tumors and 38 residual tumors after chemotherapy (P-gp and GST pi) in patients with advanced ovarian carcinoma treated with platinum- and doxorubicin-containing chemotherapy. The results of immunostaining were related to clinicopathologic prognostic factors, response to chemotherapy, and progression-free survival (PFS) and overall survival. P-gp and GST pi immunoreactivity were present in 13 (15%) and 79 cases (89%), respectively, and were not associated with any other prognostic factor or PFS or overall survival. C-erbB-2 immunoreactivity was present in 18 cases (20%) and was associated with undifferentiated histiotype (P < .05), but not with PFS or overall survival. p53 immunoreactivity was present in the nuclei of 31 cases (35%) and cytoplasm of nine cases (10%). Nuclear p53 staining was associated with grade III tumors, presence of more than 1-L ascites, and residual tumor after first laparotomy more than 2 cm. Nuclear p53 staining was associated with shorter PFS (relative risk [RR], 3.3; 95% confidence interval [CI], 2.0 to 5.6) and overall survival (RR, 2.6; 95% CI, 1.7 to 3.8). After adjustment for presence of more than 1-L ascites or age more than 50 years, nuclear p53 staining did not retain independent prognostic significance in stage III/IV tumors. The frequency of P-gp staining in residual tumors after chemotherapy (18 of 38 cases) was higher in comparison to untreated tumors (13 of 89 cases) (P < .001). No combination of prognostic parameters was able to predict response to chemotherapy adequately. Nuclear immunoreactivity of p53 in ovarian carcinomas is associated with shorter PFS and overall survival and determinants of more aggressive tumor growth. The higher frequency of P-gp immunoreactivity in residual tumors after chemotherapy points to induction of P-gp in ovarian carcinomas by doxorubicin-containing combination chemotherapy. The determination of P-gp, GST pi, c-erbB-2, and p53 does not permit more adequate prediction of response to chemotherapy.

Overexpression of p53 protein in ovarian carcinomas: correlation with histopathologic data and clinical course

The accumulation of p53 protein was analysed immunohistochemically in ovarian cancer and correlated with clinical data to further clarify the role of p53 mutations for prognosis in these patients. Tumor tissues from 126 epithelial ovarian carcinomas were analysed immunohistochemically on paraffin embedded tissue and in 21 cases on frozen tissue with monoclonal antibodies PAb 1801, PAb 421 and PAb 240. Nuclear p53 staining was found in 31 ovarian carcinomas (25%) and correlated with advanced stage of the disease (p = 0,038) and poor differentiation (P = 0,032) of the tumor. Disease-free and overall-survival time were slightly, but not significantly shortened for patients with p53 positive tumors. Immunohistochemically detectable p53 protein expression in ovarian carcinoma is associated with poor differentiation, advanced stage of the disease and a tendency for shortened disease-free and overall survival.

P53 expression and cell proliferation in squamous cell carcinomas of the head and neck.

In squamous cell carcinoma of the head and neck (SCCHN), overexpression of the p53 protein has been found in 34-80% of the tumors studied. No data are available regarding p53 expression versus tumor cell proliferation and prognosis for this tumor type. p53 protein levels were studied by immunohistochemical staining of 33 primary SCCHN using 3 antibodies (DO7, PAb 1801, and CM1) that react with different epitopes of the p53 protein. The cellular expression of p53 was compared with in vivo incorporation of the thymidine analog iododeoxyuridine (IdUrd) and expression of proliferating cell nuclear antigen (PCNA). Twenty-one tumors (64%) had a positive nuclear staining for p53 with the monoclonal antibody DO7, which reacts with a denaturation-resistant epitope in wild-type and mutant p53. PAb 1801 and CM1 reacted with 19 and 20 tumors, respectively, all of which were DO7-positive. No correlation was found between incorporation of IdUrd and p53 expression or between PCNA and p53 expression. The data indicate that intracellular accumulation of the p53 protein was related to tumor stage and localization of the tumor. No indication of a clinical or prognostic significance of p53 expression in SCCHN was found. No association between p53 deregulation and tumor cell proliferation was found.

P53 protein, PCNA staining, and DNA content in follicular neoplasms of the thyroid gland.

Forty-nine follicular adenomas and 11 follicular carcinomas of the thyroid were investigated by immunohistochemistry for the expression of p53 protein and proliferating cell nuclear antigen (PCNA). The DNA ploidy and the S-phase fraction (SPF) of the neoplasms were analysed by flow cytometry. Twelve adenomas (24 per cent) and six carcinomas (55 per cent) were DNA non-diploid (P = 0.07). The carcinomas had a higher proliferation rate than the adenomas when assessed either by SPF size (median 9.9 per cent vs. 2.9 per cent, P = 0.0003) or by PCNA staining intensity (P < 0.0001). Some scattered nuclei in two (4 per cent) adenomas and in three (27 per cent) carcinomas stained positively for p53 (P = 0.04). The two adenomas with positive staining for p53 were subserially sectioned, but no signs of invasion were found; both patients are alive and well 6 and 7 years after surgery. One of the two adenomas showing positive p53 nuclear staining was DNA aneuploid, and both were positive in PCNA staining, but their SPFs were low (2.1 and 3.3 per cent). We conclude that p53 protein expression is not confined to follicular carcinomas; scattered p53-positive cells may also be present in histologically and clinically benign follicular adenomas. Because both follicular adenomas and carcinomas may be DNA aneuploid and their SPF and PCNA staining distributions overlap, the distinction between follicular adenoma and carcinoma should still be based on histological criteria.

P53 nuclear overexpression: an independent predictor of survival in lymph node--positive colorectal cancer patients.

This study was performed to determine the prognostic significance of p53 gene overexpression in a homogeneous group of node-positive colorectal cancer patients. Paraffin sections from the primary tumors in 107 colorectal cancer patients who had preoperative serum carcinoembryonic antigen (CEA) levels less than five were examined for the expression of p53 nuclear protein by immunohistochemical staining using the monoclonal antibody PAb 1801. The nuclear p53 overexpression was compared with clinicopathologic variables and follow-up data. Positive staining was not observed in normal colorectal mucosal cells. Specific p53 nuclear staining was detected in primary tumor from 50 patients (46.7%). p53 nuclear overexpression was not significantly correlated with patients' sex, age, tumor location, differentiation, T stage, N stage, and lymphatic and/or vascular vessel invasion. With a median follow-up of 61.7 months, 60% of the p53-positive patients have had disease recurrence, versus only 35% of the p53-negative group (P = .02). Forty-two percent of the p53-positive patients died of colorectal cancer compared with 21.1% of the p53-negative patients (P = .03). By multivariate analysis, p53 overexpression was found to be an independent predictor for disease-free and disease-specific survival. In node-positive colorectal cancer patients with low preoperative CEA levels, nuclear p53 overexpression as determined by immunohistochemistry on archived tissue is an independent predictor for prognosis.