P53 Tumor Suppressor Gene Protein Research Articles

Dispersed type expression of p53 tumor suppressor gene protein is associated with a poor prognosis in patients with oral cancer

Dispersed type expression of p53 tumor suppressor gene protein is associated with a poor prognosis in patients with oral cancer

Extracellular matrix alterations in conventional renal cell carcinomas by tissue microarray profiling influenced by the persistent, long-term, low-dose ionizing radiation exposure in humans

The present study was carried out in order to examine molecular alterations of extracellular matrix (ECM), associated with cell-cell communication in conventional (clear-cell) renal cell carcinomas (cRCCs) influenced by persistent long-term, low-dose ionizing radiation (IR) exposure to patients living more than 19 years after the Chernobyl accident in Cesium 137 (137Cs)-contaminated areas of Ukraine. The ECM major components such as fibronectin, laminin, E-cadherin/beta-catenin complexes and p53 tumor suppressor gene protein, and transforming growth factor beta 1 (TGF-beta1) were immunohistochemically (IHC) evaluated in cRCCs from 59 Ukrainian patients, which represented 18 patients living in non-contaminated areas and 41 patients from 137Cs-contaminated areas. In contrast, a control group of 19 Spanish patients with analogue tumors were also investigated. For IHC evaluation, a tissue microarray technique was used. Decrease or loss and abnormal distribution of fibronectin, laminin, E-cadherin/beta-catenin complexes accompanied by elevated levels of p53 and TGF-beta1 were detected in the Ukrainian cRCCs from 137Cs-contaminated areas with statistically significant differences. Thus, our study suggests that chronic long-term, low-dose IR exposure might result in global remodeling of ECM components of the cRCCs with disruption in peri-epithelial stroma and epithelial basement membranes.

Gallbladder carcinoma: the role of p53 protein overexpression and Ki‐67 antigen expression as prognostic markers

The overexpression of p53 protein and the expression of Ki-67 antigen may affect the survival of patients with gallbladder carcinoma. This association has been tested in a series of 41 patients with relatively early carcinoma of the gallbladder. Forty-one surgical specimens from patients with a postoperative histological diagnosis of gallbladder carcinoma were studied. All patients were operated by simple cholecystectomy only because the tumours were not advanced and/or their general condition was poor. Patients submitted to radical operations were excluded. p53 expression was calculated from nuclear staining according to the intensity and extent of positive cells, as graded on a scale from 1 to 3; a combined score of >3 was considered as overexpression. Ki-67 expression was calculated by the MIB-I index: the percentage of positively stained tumour cell nuclei out of the total tumour cells counted (n = 1000); >20% of stained cells was considered positive. Twenty-nine gallbladder carcinomas (71%) overexpressed p53 protein in the cell nuclei. No significant differences were found in relation to cell differentiation on the level of tumour infiltration through the gallbladder wall. Five-year survival of patients with gallbladder carcinoma overexpressing p53 was 17.2%, while survival of patients without p53 overexpression was 30% (not significant). Twenty-four cases (58.5%) were considered positive for the MIB-I index. There were no differences between the grade of cell differentiation and wall infiltration. Five-year survival of the patients with a MIB-I positive index was 9.2% as opposed to 27.7% for those with a negative index (not significant). p53 protein nuclear overexpression and Ki-67 protein expression in gallbladder carcinoma were not related to histological differentiation, level of gallbladder wall invasion or patient survival.

Clinical implications of p53 tumor suppressor gene mutation and protein expression in esophageal adenocarcinomas: Results of a ten-year prospective study

Objective: This study was undertaken to characterize the spectrum of p53 alterations (mutations and protein expression) in surgically resected esophageal adenocarcinomas, and to correlate molecular alterations with clinicopathologic findings and outcome. Methods: Between 1991 and 2001, 91 consecutive patients with esophageal adenocarcinomas underwent subtotal esophagectomy. No patient received induction therapy. Strict clinicopathologic criteria were used to define primary esophageal adenocarcinomas. Genomic DNA was extracted from esophageal tumors, each matched with histologically normal esophageal epithelium (internal control) from the resection margin. Polymerase chain reaction was used to amplify p53 exons 4 through 10. Mutations were studied by single-strand conformation polymorphism analysis and direct DNA sequencing. Immunohistochemical testing (monoclonal antibody DO7) was used to evaluate p53 protein distribution. Results: Five-year overall survival was 27.3%. No p53 alterations (mutations and/or protein overexpression) were found in normal esophageal epithelium. A total of 57.1% (n = 52) of tumors had p53 alterations (mutations and/or protein overexpression), which on univariate analysis were associated with poor tumor differentiation (P = .001), advanced pTNM stage (P = .009), and number of involved lymph nodes (0, 1-3, >3; P = .04). Patients with p53 alterations had significantly reduced 5-year overall survival relative to patients with wild-type p53 (15% vs 46%; P = .004). The p53 mutations were predominantly G:C to A:T transitions at CpG dinucleotides (52.2%, 24/46) Conclusions: We conclude that p53 alterations (mutations and/or protein overexpression) are a predictor of reduced postoperative survival after surgical resection of esophageal adenocarcinomas and that p53 may be a clinically useful molecular marker for stratifying patients in future clinical trials. Patterns of p53 mutations suggest endogenous mutational mechanisms.J Thorac Cardiovasc Surg 2003;125:1121-31

Calbindin-d(28k): a marker of recurrence for medulloblastomas.

The expression of the Ca(2+)-binding protein calbindin-D(28k) was analyzed in medulloblastomas in relation to clinical features and other biologic markers related to cell proliferation, differentiation, p53, and cerebellar developmental regulated gene expression. Immunohistochemistry was carried out on histologic slides from a first retrospective series of 29 nonmetastatic and 10 metastatic medulloblastoma formalin-fixed, paraffin-embedded tissues, using specific antibodies against calbindin-D(28k), calretinin, alpha-parvalbumin and beta-parvalbumin, and S100 proteins. Informed consent was obtained from the subjects and/or guardians. Other biologic markers for differentiation, cell proliferation, the expression of the p53 tumor suppressor gene protein, and cerebellar developmental regulated genes were similarly investigated. A second series of 16 medulloblastomas from young patients (younger than 15 years) was added in order to validate the results obtained in the first series. Of all the markers investigated, only calbindin-D(28k) was significantly associated with prognosis. Survival and remission (i.e. recurrence free) time analysis performed on all the cases (n = 55) confirmed a high risk of death (P = 0.004) and recurrence (P = 0.003) associated with calbindin-positivity. As calbindin-positivity was predominantly observed in tumors from young patients, the authors confirmed its prognostic value in the subgroup of patients younger than 15 years (n = 37). Cox regression analysis showed a significant and independent prognostic value for calbindin expression and, to a lesser extent, the type of surgery (total or subtotal). Three risk groups were thus identified, distinguishing among the cases characterized by a total resection and calbindin-negativity (good prognosis), by a subtotal resection and calbindin-negativity (intermediary), and by calbindin-positivity (bad prognosis). The current study suggests that calbindin-positive medulloblastomas represent a subclass of aggressive tumors more frequently seen in younger patients.

Expression of p53 tumor suppressor gene in adenoid cystic and mucoepidermoid carcinomas of the salivary glands.

Seventeen adenoid cystic carcinomas (ACCs) and 27 mucoepidermoid carcinomas (MECs) occurring in the salivary glands were analyzed for p53 tumor suppressor gene alteration (exons 5-8) and protein expression. The cell proliferation activity was also examined by Ki-67 immunohistochemistry. The p53 alterations were detected in three samples (17.6%) of ACC and in four samples (14.8%) of MEC, and were only found in carcinomas arising in the minor salivary glands. The occurrence of the p53 gene alteration is less frequent in ACC and MEC than that in other kinds of tumors, and therefore does not seem to play a critical role in the course of the tumorigenesis in ACC and MEC. All ACC samples arising from the minor salivary glands exhibiting p53 gene alterations showed recurrence/metastasis, thus suggesting a poor outcome of these patients. All ACCs and three out of four MECs samples with p53 gene alterations showed the lowest degree of p53 immunostaining ratio, thus suggesting that no correlation exists between the p53 gene alterations and the p53 immunostaining in these salivary gland carcinomas. No significant relationship was demonstrated between the immunostaining ratio of either p53 or Ki-67 and the morphological growth pattern or patient clinical course in the ACC samples. The p53 immunopositivity in MEC correlated to the histological grade. The Ki-67 immunostaining ratio was also significantly related to the histological grade and the clinical course in MEC.

P53 NUCLEAR ACCUMULATION IS NOT ASSOCIATED WITH DECREASED DISEASE-FREE SURVIVAL IN PATIENTS WITH NODE POSITIVE TRANSITIONAL CELL CARCINOMA OF THE BLADDER

Although the majority of patients with node positive transitional cell carcinoma of the bladder have disease progression, a definitive subset is cured by surgery only. Nuclear accumulation of p53 has been associated with disease progression in patients with superficial transitional cell carcinoma and decreased survival in those with muscle invasive disease. We determined whether p53 status would predict survival in a cohort with nodal metastasis. We explored the comprehensive database of all 199 radical cystectomies performed at our institution between July 1988 and September 1999. The 59 patients in this database with node positive pathology comprise our study. We performed immunohistochemical analysis of specimens using the MAB1801 antibody with greater than 20% lymph node and primary tumor nucleus staining deemed positive. Additional covariates measured included patient age, sex, pathological disease stage, adjuvant chemotherapy and nodal stage. Disease-free survival curves were generated for the various covariates and compared using the log rank test. The Cox proportional hazards technique was used to determine covariate adjusted p53 survival. In the cohort overall median disease-free survival was only 21 months, although 18% of patients were disease-free at 5 years. There was evidence of p53 nuclear accumulation in 54% of cases and complete agreement of nodal with bladder p53 nuclear accumulation. No significant baseline differences were noted in the covariates with respect to p53 nuclear accumulation. For stratum specific disease-free survival univariate and multivariate analyses revealed that only pathological stages p0-p2b versus p3-p4 (hazards ratio 2.86, p = 0.03), and nodal stages N2 versus N1 and N3 versus N1 (hazards ratio 3.84, p = 0.01 and hazards ratio 13.3, p = 0.0002, respectively) were significantly associated with prolonged disease-free survival, while p53 nuclear accumulation was not. Despite credible evidence for p53 nuclear accumulation prognostication in patients with in situ and invasive transitional cell carcinoma, this marker is not predictive of disease-free survival in node positive disease.

Expression of Regulatory Gene Protein p53 in Human Gametes and Preembryos

Introduction: Human gametes and preembryos may undergo cell arrest and/or apoptosis in vitro. The specific signals that trigger, and proteins that regulate, these events are unknown. The p53 (tumor suppressor gene) protein has the ability to regulate cell arrest and/or apoptosis in response to DNA damage. While normally a nuclear protein, p53 can migrate to the nuclear membrane and cell cytoplasm if activated. The objective of this study was to determine expression of the p53 protein in human gametes and preembryos up to the blastocyst stage.

Evaluation of a commercial system for the identification of Ornithobacterium rhinotracheale.

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Immunohistochemical detection of p53 tumor suppressor gene protein in canine epithelial colorectal tumors.

Eighty canine epithelial colorectal tumors obtained by excisional biopsy were evaluated immunohistochemically for p53 tumor suppressor gene protein. Dogs in the study average 6.9 years of age (range, 1-12.5 years). A standard avidin-biotin immunohistochemical protocol incorporated a polyclonal antibody of rabbit origin (CM-1) as the primary antibody. Positive staining was observed within all subcategories of lesions, including hyperplastic polyps 1/2 (50%), adenomas 14/29 (48%), carcinomas in situ 9/22 (41%), adenocarcinomas 3/4 (75%), and invasive carcinomas 8/23 (35%). A total of 35/80 (44%) positive tumors wee identified. Fifteen of 31 (48%) benign tumors labeled for p53 protein compared to 20/49 (41%) malignant tumors. Survival data was available for 57/80 (71%) dogs. The average age of dogs within the group with survival data was 4.4 years. Males predominated 34/57 (60%). Mean survival time was 20.6 months. There was no significant difference in survival time between dogs grouped according to p53 immunoreactivity, cellular stain location, or tumor site. A statistically significant increase in survival time was observed between dogs with clean surgical margins and those without (P < 0.018) and for dogs with adenomas or carcinomas in situ over dogs with invasive carcinomas (P < 0.02). In this study, the overall greater positive staining frequency of benign lesions compared to malignant lesions is contrary to data derived from similar immunohistochemical analyses of human tumors and is incongruous with the theorized late-stage participation of the p53 protein in the development of human colorectal cancers. The results of this study suggest that if the p53 tumor suppressor gene protein is involved in the progression of canine colorectal tumors, it may play a relatively early role, possibly analogous to the early appearance of p53 overexpression in precancerous lesions of human ulcerative colitis. Immunohistochemical detection of p53 was not useful prognostically.

P53 tumour suppressor gene protein expression in early and advanced gallbladder carcinoma.

Gallbladder carcinoma is one of the most frequent malignant tumours occurring in Chile and the mortality rate in both sexes ranks among one of the highest in the world. Mutation of p53 tumour suppressor gene has been demonstrated in many tumours. Our aim was to determine protein expression of p53 gene in early and advanced gallbladder carcinoma. Protein expression of gene p53 was studied by immunohistochemical means in 191 gallbladder carcinomas (157 primary tumours, 34 metastases) and 25 controls. In 86 out of 191 cases (45%), protein expression of gene p53 was observed. Differences related to sex, age, or race were not observed. All gallbladder controls were negative. Twenty-five per cent of well-differentiated tumours were p53 positive, while moderate or poorly differentiated carcinomas reached 50% (P = 0.04). p53 expression was observed in 23.5% of early carcinomas and in 48.2% of advanced carcinomas (P = 0.01). No differences between primary tumours and metastasis were demonstrated. Protein expression of p53 tumour suppressor gene is observed in 45% of gallbladder carcinomas. The absence of expression in controls and in normal mucosa adjacent to tumours suggests its utility in differentiating atypical gallbladder epithelia from neoplastic lesions.

P53 tumor suppressor gene protein expression in premalignant and malignant skin lesions of kidney transplant recipients

Kidney transplant recipients have an increased incidence of skin cancer, the cause of which is likely multifactorial. Inactivation of the tumor suppressor gene p53 protein may be important. Chemoprophylaxis of skin cancer with retinoids is beneficial in these patients. Our purpose was to investigate the immunohistochemical expression of p53 protein in premalignant and malignant cutaneous lesions in kidney transplant recipients and the effect of low-dose etretinate on p53 expression. Paraffin sections were stained with the monoclonal antibody DO-7. Immunoreactivity of p53 was observed in 59% of basal cell carcinomas and more than 60% of squamous cell carcinomas, Bowen's disease, dysplastic lesions, and viral warts. No demonstrable effect of etretinate on p53 expression could be determined. The high prevalence of p53 immunoreactivity in premalignant and malignant skin lesions of kidney transplant recipients supports a role for p53 protein in skin cancer. This could be caused by mutation of the p53 gene, inactivation, or failure of degradation of p53 protein.

Apoptosis and p53 suppressor gene protein expression in human anterior pituitary adenomas.

Human anterior pituitary adenomas proliferate and express the p53 tumour suppressor gene protein, but it is not known if apoptosis (programmed cell death) occurs. Therefore, the detection of apoptosis was undertaken in tumorous human anterior pituitary tissue and compared with p53 protein expression, tumour type and tumour size. Apoptosis (detected by the in situ end labelling technique) and p53 suppressor gene protein (detected by DO.1-antibody immunocytochemistry) were determined in formalin-fixed and paraffin-embedded tissue from 37 human pituitary adenomas (2 macroprolactinomas, 9 somatotrophinomas and 26 non-functioning adenomas). Two normal anterior pituitaries were also included in this study. Pre-operative tumour size was scored 1 to 4 from magnetic resonance imaging radiology. Apoptosis was found in 7 of 29 tumours (24%), 11% of somatotrophinomas and 33% of non-functioning adenomas, although this difference was not significant. The p53 tumour suppressor protein was found in 7 of 31 tumours (23%), 33% of somatotrophinomas and 19% of non-functioning adenomas. Apoptosis and p53 protein expression were not found in normal anterior pituitary. In conclusion, apoptosis occurs in human anterior pituitary adenomas, but no significant association was found between apoptosis and p53 protein expression, tumour type or tumour size.

P53 tumor suppressor gene protein expression in cervical cancer: relationship to prognosis

Objective: Mutation of the p53 gene can be found in several human tumors. We tested the hypothesis whether overexpression of p53 protein is a parameter of more aggressive disease in patients with cervical cancer. Study design: In this study, we describe the effects of p53 overexpression in 156 patients with cervical cancer (Figo stage IB-IV) by assessing expression patterns of the p53 gene product using a monoclonal anti-p53 antibody (DO7). Results: Overexpression of p53 tumor suppressor gene protein was observed in 30.2% of the tumors, low expression in 30.7% and 39.1% of the tumors showed no p53 immunoreactivity. With increase in stage, p53 overexpression raised from 20.1% in stage IB to 60% in stage IV. A significant correlation between p53 overexpression and disease-free survival of patients was observed, however, after stratification for stage, this effect disappeared. Conclusions: The p53 mutation expressed as p53 tumor suppressor gene protein overexpression is a late event in cervical cancer genesis and does not appear to be of prognostic significance in cervical cancer.

Increased p53 Protein Does Not Correlate to p53 Gene Mutations in Microdissected Human Testicular Germ Cell Tumors

Purpose To determine if primary testicular germ cell tumors that overexpress p53 tumor suppressor gene protein have p53 gene mutations. Materials and Methods We examined 30 primary testicular tissues from 26 patients representing two groups. Group one consisted of eleven cases (6 nonseminomatous germ cell tumors and 5 seminomas) in which tissue samples for DNA analysis were microdissected from paraffin block regions with elevated immunohistochemical staining for p53 protein. Group two consisted of 19 testis tumor tissues which had been fresh frozen and were chosen to correspond to archival tissue specimens exhibiting elevated levels of p53 protein. The DNA was extracted from these tissues and subjected to exon specific amplification by polymerase chain reaction (PCR) and cold single-strand conformation polymorphism (Cold SSCP) analysis. Results In these cases with elevated p53 protein, no p53 gene exon 5-8 mutations were detected except 1 seminoma with a codon 140 silent mutation (no protein alteration). Conclusions Testicular tumors appear to exhibit elevated levels of wild-type p53 protein, the significance of which is yet to be elucidated.

Increased p53 protein does not correlate to p53 gene mutations in microdissected human testicular germ cell tumors.

To determine if primary testicular germ cell tumors that overexpress p53 tumor suppressor gene protein have p53 gene mutations. We examined 30 primary testicular tissues from 26 patients representing two groups. Group one consisted of eleven cases (6 nonseminomatous germ cell tumors and 5 seminomas) in which tissue samples for DNA analysis were microdissected from paraffin block regions with elevated immunohistochemical staining for p53 protein. Group two consisted of 19 testis tumor tissues which had been fresh frozen and were chosen to correspond to archival tissue specimens exhibiting elevated levels of p53 protein. The DNA was extracted from these tissues and subjected to exon specific amplification by polymerase chain reaction (PCR) and cold single-strand conformation polymorphism (Cold SSCP) analysis. In these cases with elevated p53 protein, no p53 gene exon 5-8 mutations were detected except 1 seminoma with a codon 140 silent mutation (no protein alteration). Testicular tumors appear to exhibit elevated levels of wild-type p53 protein, the significance of which is yet to be elucidated.

Immunohistochemical detection of p53 protein in preneoplastic lesions and squamous cell carcinoma of the head and neck.

Alterations in the p53 tumor suppressor gene are the most frequent genetic abnormalities in human cancers. The p53 protein is present in normal cells, and is assumed to induce G1 arrest or apoptosis in the presence of DNA lesion. The mutant protein lacks this property. Squamous cell carcinomas of the head and neck (SCCHN) are related to carcinogens in tobacco and alcohol, and provide a good model of multiple-step carcinogenesis in association with DNA damage and p53-related tumorigenesis. Stabilization of the mutant p53 protein allows immunohistochemical analyses (IHC) to be routinely used to demonstrate the mutant p53 protein in tissue samples, whereas normal p53 protein is undetectable. Ninety-nine squamous cell carcinomas, 8 in situ carcinomas, 31 preneoplastic lesions and 79 normal carcinogen-exposed mucosas of the head and neck from a total of 107 patients were examined for the expression of p53 tumor suppressor gene protein. Samples were collected before treatment, and stained with p53 specific mono- and polyclonal antibodies (DO-7, Pab 1801 and 240, CM1) using an indirect immunoperoxidase technique. Proliferating cell nuclear antigen (PCNA) provided semiquantitative estimates of proliferation. The main localizations were the pharynx (64/107) and the larynx (21/107). Positive IHC detection of p53 was observed in 9% of normal-appearing carcinogen-exposed mucosas, 37% of hyperplasias, 68% of dysplasias, 75% of in situ carcinomas, and 56/99 (56.5%) of primary tumor samples. Mucosas from 15 control patients under 10 years of age were negative. There was no correlation between p53 IHC and localization, differentiation or TNM staging.(ABSTRACT TRUNCATED AT 250 WORDS)

Association of immunohistochemical p53 tumor suppressor gene protein overexpression with prognosis in highly proliferative human mammary adenocarcinomas.

An increasing body of evidence suggests that in addition to conventional histopathologic tumor characteristics, DNA content measurements, cell kinetic data, and investigations of tumor suppressor gene expressions might be of valuable information in breast cancer patients. Against this background we investigated immunohistochemically overexpression of the interphase associated protein proliferating cell nuclear antigen (PCNA) and the mutant p53 protein in routinely paraffin-embedded surgical specimens from 180 breast cancer patients with known nuclear DNA profiles. The mean clinical follow-up was 16 years (range 13-20 years). The percentage of PCNA immunoreactive tumor cell nuclei ranged between < 5% and 60% (mean 13.59 +/- 10.85%). There was a direct association between high levels of PCNA expression (> 20%) and p53 protein overexpression (p = 0.001), high histologic tumor grade (p = 0.009), and DNA aneuploidy (p = 0.019). Mutant p53 protein overexpression was found in 44 of 180 (24%) cases and was significantly related to high histologic tumor grade (p = 0.004), DNA aneuploidy (p = 0.001), and high levels of PCNA expression (p = 0.001). Patients with highly proliferative carcinomas (> 20% PCNA expression) had a shortened distant metastases-free survival when their neoplasms overexpressed p53. In contrast, the distant metastases-free survival of patients with highly proliferative, p53-negative tumors was significantly longer (p = 0.03). Immunohistochemical p53 protein overexpression thus appears to be indicative of an increased malignant potential in breast cancer patients. Highly proliferative tumors composed of p53 immunoreactive neoplastic cells clinically seem to behave more aggressively than the highly proliferative p53-negative tumors.

Prevalence of serum antibodies against the p53 tumor suppressor gene protein in various cancers.

We have developed 2 new quantitative methods for measuring anti-p53 antibodies in human serum. Using these methods we analyzed 1,392 sera from patients with various malignancies and 230 sera from individuals without malignancy. Highest prevalence of anti-p53 antibodies was associated with ovarian and colon cancers (15%), followed by lung (8%) and breast (5%) cancers. Prevalence in other malignancies was lower (< 4%). In hospitalized patients and apparently healthy individuals, prevalence was very low (< 2 and 1% respectively). Extremely high antibody concentrations (> 10(5) U/L) were found in 5 ovarian, 2 breast, 1 lung and 1 colon cancers. Sequential analysis of 6 positive samples has shown that the p53 antibody test may have potential for patient monitoring. The p53 antibody-positive sera from breast cancer patients were associated with tumors that were steroid hormone receptor-negative (p < 0.002). We propose that the measurement of p53 antibodies is a relatively specific serological test for cancer, which can be performed with easily automatable and quantitative methodologies and may be further exploited for patient monitoring, prognosis, diagnosis and probably screening for selected cancers.

Immunohistochemical Expression of P53 Tumor Suppressor Gene Protein in Adult Germ Cell Testis Tumors: Clinical Correlation in Stage I Disease

P53 tumor suppressor gene protein immunostaining was evaluated in the primary tumor of adult testicular germ cell cancer to assess if P53 expression would serve as a clinically useful tumor marker. Representative archival tissues from 152 orchiectomy specimens were studied for P53 immunohistochemistry. Seminoma and nonseminomatous germ cell tumor constituents revealed P53 expression via immunohistochemistry in 90% and 94% of the cases, respectively. For seminoma, there was a trend toward decreased P53 expression with advancing stage. For nonseminomatous germ cell tumor, although all cellular components showed variable P53 expression, P53 expression in embryonal carcinoma constituents increased among stages of disease. A third of pathological stage I cancer patients exhibited 2+ or greater P53-embryonal staining compared with 61% with stage II (p = 0.0670) and 67% with stage III (p = 0.0815) disease, respectively (Kruskal-Wallis, 2-sided test).As a secondary objective, we wanted to determine if P53 immunohistochemistry would be useful to predict occult disease in clinical stage I nonseminomatous germ cell tumor. This group was studied for P53-embryonal immunohistochemistry, the presence of vascular invasion and the quantitative determination of percentage of embryonal carcinoma in the primary tumor in a multivariate fashion to assess if these tests could be clinically useful to predict occult disease. Degree of P53 immunostaining of the embryonal component in the primary tumor was statistically greater for stage II by univariate logistic regression analysis (p = 0.0362). Similarly, the per cent embryonal cancer (p = 0.0002) and vascular invasion (p = 0.0005) were highly significant as predictors of occult stage II disease via the univariate testing. By multivariate logistic regression analysis, the model consisting of per cent embryonal cancer and vascular invasion provided the best prediction of occult disease in the clinical stage I cohort. In addition, this model had the highest sensitivity and specificity of all multivariate models considered. The addition of P53-embryonal staining did not improve predictability nor sensitivity/specificity.The P53 tumor suppressor gene protein is expressed to some degree in most testicular germ cell tumors and degree of staining/expression varies according to stage of disease. From the standpoint of a clinically useful primary tumor risk factor for predicting occult disease, vascular invasion by the tumor and percentage of embryonal carcinoma component in the tumor are more useful than P53 immunohistochemistry.