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W F Benedict

Publications and source records attributed to W F Benedict.

At least 19 recordsLinked to original sources
PubMed2006

Efficacy of a single intravesical treatment with Ad-IFN/Syn 3 is dependent on dose and urine IFN concentration obtained: implications for clinical investigation.

There is a need to improve the treatment of superficial bladder cancer. One area which holds promise is intravesical gene therapy. Recently, studies undertaken by us have shown that marked tumor regression of bladder cancers occurred after two daily intravesical administrations of an adenovirus encoding human interferon alpha (Ad-IFNalpha) using a mouse superficial bladder cancer model in which human bladder tumors are growing. A dose of 1 x 10(11) particles/ml (P/ml) was used along with 1 mg/ml of Syn3, a gene transfer-enhancing agent. Since clinical studies are being planned using this approach, it became critical to determine if one exposure and lower particle number could be equally effective. We report that indeed a single dose of Ad-IFNalpha in Syn3 at doses of 1 x 10(10)-1 x 10(11) P/ml is highly effective in reducing the size of the tumors, whereas 1 x 10(9) P/ml was not. Efficacy was also correlated with the level of IFN produced in the urine after treatment. Based on the results of the present studies, a Phase I trial is being planned for superficial bladder cancer, which will involve a single initial treatment with Ad-IFNalpha/Syn3 and measurement of IFN in the urine over time as an indicator of adequate gene transfer and expression.

Administration, Intravesical↗
PubMed2001

Susceptibility of nonpromoter CpG islands to de novo methylation in normal and neoplastic cells.

BACKGROUND: Many cancers display alterations in methylation patterns of CpG islands--stretches of DNA rich in CpG dinucleotides often associated with gene promoters that are involved in initiation of gene transcription. This methylation may perturb expression of genes critical to the regulation of cell proliferation. Aberrant methylation is not limited to a few genes or to promoter regions but has been found on a genome-wide scale in a variety of neoplasias, including colorectal cancer and acute myelogenous leukemia. Our goal was to characterize, in a quantitative manner, the profiles of abnormally methylated genes that may be specific for different cancers. METHODS: Using a quantitative assay, methylation-sensitive single nucleotide primer extension (MS-SNuPE), we have analyzed the methylation levels of promoter and exonic (coding region) CpG islands of two cyclin-dependent kinase inhibitors [p15(INK4B) and p16(INK4A)] and the PAX6 gene, which encodes a transcriptional factor involved in neuronal proliferation, in DNA samples taken from patients with chronic myelogenous leukemia, acute myelogenous leukemia, myelodysplastic syndrome, and colorectal cancer. RESULTS: De novo methylation of all three exonic loci in tumors--relative to baseline levels found in nontumor tissue or blood--was observed in hematologic neoplasias and in solid tumors as well as in normal colonic tissue. However, methylation of promoter regions was more limited. Moreover, two different patterns of promoter methylation distinguished the leukemias from colorectal cancer: p15 promoter hypermethylation was found only in the leukemias, and p16 promoter hypermethylation occurred only in colon tumors. However, we did not address this issue prospectively; therefore, such an observation is only hypothesis generating. CONCLUSIONS: The methylation patterns that we observed suggest that exonic CpG islands are more susceptible to de novo methylation than promoter islands and that methylation may be seeded in exonic regions, from which it can spread to other islands, including promoter regions. Subsequent selection of cells with a growth advantage conferred by spread of methylation into and inactivation of a particular promoter might then contribute to the genesis of a specific type of cancer.

Acute Disease↗
PubMed2001

Correlation of immunohistochemical molecular staging of bladder biopsies and radical cystectomy specimens.

PURPOSE: To determine the relationship of p53, retinoblastoma (RB), and p16 expression between precystectomy transurethral resection bladder (TURB) biopsy and matched cystectomy specimens; and to determine the value of p53 immunoreactivity for predicting progression and survival in patients undergoing radical cystectomy. METHODS AND MATERIALS: We performed p53 immunohistochemical staining on matched archival TURB and cystectomy specimens taken from 40 patients. Twenty-seven and 26 of these patients were also evaluated for RB and p16 expression, respectively. RESULTS: Twenty-eight (70%) of the TURB and 22 (55%) of the cystectomy specimens stained positive for p53. RB and p16 protein expression were altered in 19 (70%) and 19 (73%) of the TURB specimens, respectively, and 19 (70%) and 19 (73%) of the cystectomy specimens, respectively. There was a strong correlation between p53, RB, and p16 expression and TURB and cystectomy specimens (all p < 0.001). In preoperative and postoperative multivariate analyses, biopsy p53 and cystectomy p53 were independently associated with disease progression (p = 0.049 and p = 0.034, respectively) and bladder cancer-related death (p = 0.044 and p = 0.037, respectively). CONCLUSION: p53, RB, and p16 expression patterns on TURB specimens correlate with cystectomy specimens. p53 immunoreactivity is an independent predictor of disease progression and bladder cancer survival. These data support the potential of prognostic staging using immunohistochemical analysis on bladder biopsy specimens prior to neoadjuvant or definitive therapy.

Adult↗
PubMed2001

Gene therapy for superficial bladder cancer.

In this review, the basics of gene therapy and the strategies to increase the therapeutic effect of gene therapy for superficial bladder cancer are discussed. Strategies considered in detail are modification of the structure of vectors, modification of the promoters of viral vectors and the timing and route of vector administration. Although all of these modifications have shown some degree of improvement for gene transfer, the use of polyamides intravesically in conjunction with an adenoviral system shows the most promise and the greatest potential to supplement or even replace the current treatment modalities for superficial bladder cancer.

Adenoviridae↗
PubMed2000

Differential retinoblastoma and p16(INK4A) protein expression in neuroendocrine tumors of the lung.

BACKGROUND: Neuroendocrine neoplasms of the lung represent a wide spectrum of phenotypically and biologically distinct entities. Their histopathologic diagnosis, which carries therapeutic and prognostic significance, may sometimes be difficult because of their overlapping features. We previously demonstrated that large cell neuroendocrine carcinomas (LCNECs) and small cell lung carcinomas (SCLCs) failed to show positive nuclear staining of RB protein (RB-), whereas typical and atypical carcinoids (TCs and ACs) showed nuclear RB immunostaining (RB+). METHODS: In the current study, a series of 58 surgically resected lung tumors, of which 33 tumors were initially diagnosed as SCLCs and 25 as TCs or ACs, were studied for RB and p16 protein expression by immunohistochemistry. They were also reviewed for their pathologic diagnosis; the reviewers were blinded to the RB and p16 protein status. RESULTS: Nineteen tumors were diagnosed as TCs, 5 as ACs, 7 as LCNECs, and 27 as SCLCs. Three of seven LCNECs were RB+, whereas the other four were RB-. In contrast, all 19 TCs were RB+ and all 27 SCLCs were RB-. In addition, two of five ACs were RB+, whereas the other three were RB-. Interestingly, all 3 RB+ LCNECs and the 1 RB+ AC tested failed to show nuclear staining of p16 protein in any tumor cells (p16-), although some normal stromal cells showed nuclear staining of p16 protein (p16+) as positive internal controls, indicating loss of p16 function in these tumors. It is also noteworthy that the three RB+ LCNECs were initially diagnosed as SCLCs and one of the RB- ACs was initially considered a TC. With the exception of TCs, tumors were significantly more prevalent among heavy smokers with >20 pack-years compared with nonsmokers and light smokers with < or = 20 pack-years (P < 0.01). CONCLUSIONS: These findings suggest that all SCLCs and LCNECs have abnormalities in the p16:RB pathway, as do at least certain ACs, whereas the p16:RB pathway is normal in TCs.

Adult↗
PubMed2000

An improved intravesical model using human bladder cancer cell lines to optimize gene and other therapies.

Orthotopic implantation of human bladder cancer cells into immunodeficient mice is an important tool for studying the biology and effects of therapy. Nevertheless, the incidence of tumor implantation and growth by transurethral instillation of the human bladder cancer cells into murine bladders has been low or not reproducible. However, using a modified intravesical technique and the human bladder cancer cell lines, KU-7 and UM-UC-2, we have been able to obtain a high and reproducible incidence of superficial bladder tumors. Furthermore, intravesical administration of the LacZ adenovirus vector resulted in significant beta-galactosidase expression in these bladder tumors as well as the normal urothelium, which was associated with the removal of the glycosoaminoglycan layer. Because this modified technique produces a high incidence of superficial human tumor growth and allows the efficacy of gene transfer to be evaluated, it should be a useful model for the study of intravesical gene therapy for human bladder cancer.

Adenoviridae↗
PubMed2000

Retinoblastoma protein-initiated cellular growth arrest overcomes the ability of cotransfected wild-type p53 to induce apoptosis.

The retinoblastoma gene, RB, participates in the regulation of the G1/S-phase transition and in p53-mediated apoptosis. We have previously reported that stably transfected RB functions as a growth and tumour suppressor in HTB9 human bladder carcinoma cells, which carry a mutation of the p53 gene at codon 280 and lack RB expression. To elucidate the potential role of RB in the regulation of p53-mediated apoptosis, we transfected a wt p53 expression plasmid under the control of the human cytomegalovirus promoter into parental and RB-transfected HTB9 cells. The p53(+)/RB(-)cells were susceptible to apoptosis under various experimental conditions: 1) incubation in serum-free culture for 72 h, 2) short-term (6 h) or long-term (48 h) exposure to etoposide, and 3) culturing in soft agar. In contrast, p53(+)/RB(+)cells were significantly resistant to apoptosis under similar conditions and exhibited efficient growth arrest, as measured by laser scanning cytometry. Tumorigenicity in nude mice of parental HTB9 cells was lost by exogenous expression of wt p53. Likewise, none of mice injected subcutaneously with either p53(-)/RB(+)or p53(+)/RB(+)cells developed tumours, indicating that RB allows suppression of tumorigenesis, regardless of p53 status. These results suggest that the growth-inhibitory function of RB may overcome the ability of wt p53 to induce apoptosis.

Animals↗
PubMed2000

Genetic modeling of human urinary bladder carcinogenesis.

We developed a model of human urinary bladder cancer progression from in situ precursor lesions to invasive carcinoma using whole organ histologic and genetic mapping. The model represents a high-density and detailed analysis regarding allelic losses on chromosomes 4, 8, 9, 11, and 17 as revealed by testing of 234 samples obtained from five cystectomy specimens. The samples corresponded to microscopically identified intraurothelial precursor conditions ranging from dysplasia to carcinoma in situ and invasive cancer. The initial analysis of paired normal and tumor DNA samples disclosed allelic losses in 72 of 225 tested hypervariable DNA markers. Subsequent use of these markers on all mucosal samples revealed that 47 had alterations with a statistically significant relation to urothelial neoplasia. The allelic losses clustered in 33 distinct chromosomal regions, indicating the location of putative tumor suppressor genes involved in the development and progression of urinary bladder cancer. Some of the markers with statistically significant allelic losses mapped to the regions containing well-characterized tumor suppressor genes but many were located in previously unknown loci. The majority of statistically significant allelic losses (70%) occurred early in low-grade intraurothelial dysplasia, and some of them involved adjacent areas of morphologically normal mucosa preceding the development of microscopically recognizable precursor lesions. The remaining 30% of markers developed allelic losses in the later phases of urothelial neoplasia, implicating their involvement in progression to invasive disease. Markers exhibiting allelic losses in early phases of urothelial neoplasia could be used for detection of occult preclinical or even premicroscopic phases of urinary bladder cancer, whereas markers that showed allelic losses in the later phases of the process could serve as indicators of progression to invasive disease. The approach used in this study facilitates genome-wide modeling of cancer progression and provides important chromosomal landmarks for more specific studies of multistep urinary bladder carcinogenesis.

Aged↗
PubMed2000

TabBO: a model reflecting common molecular features of androgen-independent prostate cancer.

We established two human prostate cancer cell lines, MDA PCa 2a and MDA PCa 2b, the TabBO model system, that reflect common features of human androgen-independent prostate cancer that are not present in other model systems: bone origin, prostate-specific antigen production, androgen receptor expression, and androgen sensitivity. We therefore hypothesized that molecular pathways in our model system reflect common alterations responsible for the progression of a subset of human prostate cancer. Progression to androgen independence has been hypothesized to be largely associated with impairment of the regulation of cell growth or apoptosis of prostate cancer cells. Therefore, in this study, we examined molecular markers known or suspected to be important in prostate cancer progression and key regulators of cell growth and apoptosis: p53, p21WAF1/CIP1, Bcl-2, Bax, retinoblastoma (Rb), and p16INK4A/MITS1. We analyzed the expression of these markers in the cell lines, their tumor of origin, and tumors derived from the cell lines by s.c. inoculation into nude mice. DNA sequencing of the entire open reading frames of the p53 and p21 genes revealed no mutations. Additionally, accumulation of the p53 protein was not found by Western blot analysis, nor was overexpression of the Bcl-2 oncoprotein detected. Bax expression was detected in MDA PCa 2a cells, whereas it was absent in MDA PCa 2b. Rb and p16 protein expression was normal as measured by both Western blot and immunochemical analyses. Immunohistochemical studies of p53, p21, Bcl-2, and Rb in both samples from the original human cancer from which the lines were derived and mouse xenografts derived from the lines revealed similar levels of protein. These results are consistent with reports indicating that 40-50% of bone metastases of prostate cancer have wild-type p53, 50-70% do not overexpress the Bcl-2 protein, and mutations in the p21 gene are rare. Therefore, we conclude that MDA PCa 2a and MDA PCa 2b reflect molecular pathways in a common subset of human androgen-independent prostate cancer and that important molecular players in apoptosis (namely, p53 and Bcl-2) seem to be intact in this subset of androgen-independent prostate cancer. Understanding the signal-transduction pathways operating in these cell lines may help to identify therapeutic targets for prostate cancer.

Androgens↗
PubMed1999

Superimposed histologic and genetic mapping of chromosome 9 in progression of human urinary bladder neoplasia: implications for a genetic model of multistep urothelial carcinogenesis and early detection of urinary bladder cancer.

The evolution of alterations on chromosome 9, including the putative tumor suppressor genes mapped to the 9p21-22 region (the MTS genes), was studied in relation to the progression of human urinary bladder neoplasia by using whole organ superimposed histologic and genetic mapping in cystectomy specimens and was verified in urinary bladder tumors of various pathogenetic subsets with longterm follow-up. The applicability of chromosome 9 allelic losses as non-invasive markers of urothelial neoplasia was tested on voided urine and/or bladder washings of patients with urinary bladder cancer. Although sequential multiple hits in the MTS locus were documented in the development of intraurothelial precursor lesions, the MTS genes do not seem to represent a major target for p21-23 deletions in bladder cancer. Two additional tumor suppressor genes involved in bladder neoplasia located distally and proximally to the MTS locus within p22-23 and p11-13 regions respectively were identified. Several distinct putative tumor suppressor gene loci within the q12-13, q21-22, and q34 regions were identified on the q arm. In particular, the pericentromeric q12-13 area may contain the critical tumor suppressor gene or genes for the development of early urothelial neoplasia. Allelic losses of chromosome 9 were associated with expansion of the abnormal urothelial clone which frequently involved large areas of urinary bladder mucosa. These losses could be found in a high proportion of urothelial tumors and in voided urine or bladder washing samples of nearly all patients with urinary bladder carcinoma.

Chromosome Aberrations↗
PubMed1999

Level of retinoblastoma protein expression correlates with p16 (MTS-1/INK4A/CDKN2) status in bladder cancer.

Recent studies have shown that patients whose bladder cancer exhibit overexpression of RB protein as measured by immunohistochemical analysis do equally poorly as those with loss of RB function. We hypothesized that loss of p16 protein function could be related to RB overexpression, since p16 can induce transcriptional downregulation of RB and its loss may lead to aberrant RB regulation. Conversely, loss of RB function has been associated with high p16 protein expression in several other tumor types. In the present study RB negative bladder tumors also exhibited strong nuclear p16 staining while each tumor with strong, homogeneous RB nuclear staining were p16 negative, supporting our hypothesis. To expand on these immunohistochemical studies additional cases were selected in which the status of the p16 encoding gene had been determined at the molecular level. Absent p16 and high RB protein expression was found in the tumors having loss of heterozygosity within 9p21 and a structural change (mutation or deletion) of the remaining p16 encoding gene allele, confirming the staining results. These results strongly support the hypothesis that the RB nuclear overexpression recently associated with poor prognosis in bladder cancer is also associated with loss of p16 function and implies that loss of p16 function could be equally deleterious as RB loss in bladder and likely other cancers.

Biopsy↗
PubMed1999

Expression of p16, Rb, and cyclin D1 gene products in oral and laryngeal squamous carcinoma: biological and clinical implications.

Cyclin D1, p16, and Rb genes play a critical role in the regulation of the G1-S transition of the cell cycle and are frequently altered in several neoplastic entities. Analysis of the protein products of these genes by molecular and immunohistochemical methods provides information on their functional status and allows for the phenotypic evaluation of tumor cells. We performed Western blotting and immunohistochemical analysis on tissues from 35 primary oral and laryngeal squamous carcinoma specimens with previous molecular analysis of the p16 gene and correlated the results with relevant clinicopathologic factors. Our study shows significant concordance between Western blotting and immunostaining results for cyclin D1 (P = .01), p16 proteins (P = .01), and Rb (P = .04). Heterogeneous staining of tumor cells and the positivity of non-neoplastic host elements for Rb by immunohistochemistry contributed to the discrepancy noted in some tumors by Western blotting. Significant reciprocal relationship between p16 and Rb proteins was observed (P < .001); in most tumors, absence of p16 (89%) and detectable Rb (94%) proteins were found. Two tumors had negative cyclin D1 expression, and one third overexpressed this protein. There was a lack of correlation between cyclin D1 overexpression and the clinicopathologic factors studied. Our results indicate that the absence of p16 in most of these tumors may constitute an early tumorigenic event and that the loss of the Rb function plays a minor role in HNSC.

Adult↗
PubMed1998

Elevated and absent pRb expression is associated with bladder cancer progression and has cooperative effects with p53.

Rb protein (pRb) expression was evaluated in 185 cases of transitional cell carcinoma of the bladder from patients that underwent radical cystectomy. Tumors were stratified into three categories based on the percentage of nuclei expressing pRb: (a) 0, 0% of tumor cells showing nuclear reactivity; (b) 1+, 1-50% of tumor cells showing nuclear reactivity; and (c) 2+, >50% of tumor cells showing nuclear reactivity. Cases with undetectable (pRb 0) and high (pRb 2+) pRb reactivity had identical rates of recurrence. These cases had significantly higher recurrence (P = 0.0001) and lower survival rates (P = 0.0002) compared to cases with moderate (pRb 1+) pRb reactivity, indicating that high levels of pRb expression may reflect a dysfunctional (altered) Rb pathway. The tumors were also examined for alterations in p53 expression; patients with tumors altered in both p53 and pRb had significantly increased rates of recurrence (P < 0.0001) and survival (P < 0.0001) compared to patients with no alterations in either p53 or pRb; patients with alterations in only one of these proteins had intermediate rates of recurrence and survival. These results suggest that: (a) bladder cancers with high pRb expression do not show the tumor suppressor effects of the protein; and (b) alteration in both p53 and pRb may act in cooperative or synergistic ways to promote tumor progression.

Carcinoma, Transitional Cell↗
PubMed1998

p53 and RB expression predict progression in T1 bladder cancer.

The optimal clinical management of minimally invasive (stage T1) bladder cancer is controversial. T1 bladder cancers share characteristics of both noninvasive (Ta) papillary cancer and high stage, muscle-invasive bladder cancers. Patients with T1 bladder cancer have a higher risk of cancer progression and death than do patients with Ta bladder cancer. However, this risk is much lower than that of patients with high-stage bladder cancers. Methods of identifying T1 bladder cancer patients at greatest risk for progression may significantly improve clinical management. We retrospectively evaluated two tumor suppressor genes, p53 and RB, as potential prognostic markers for progression in a cohort of 45 patients with pT1 bladder cancer. Median follow-up for these individuals was greater than 3.5 years. Of this group, 58% had altered p53 expression based on positive p53 immunostaining. Three patterns for RB nuclear protein staining were observed: absent, heterogeneous (normal), and strongly homogeneous. Progression-free survival was similar for patients with loss of RB protein expression and those with apparent overexpression of RB protein. Therefore, both staining patterns were considered abnormal. Patients with normal expression of both proteins (i.e., p53 negative and RB heterogeneously positive) had an excellent outcome, with no patient showing disease progression, whereas patients with abnormal expression of either or both proteins had a significant increase in progression (P = 0.04 and P = 0.005, respectively). These data support the stratification of T1 bladder cancer patients based on p53 and RB nuclear protein status and suggest that patients with normal protein expression for both genes can be managed conservatively, whereas patients with alterations in one and particularly both genes require more aggressive treatment.

Cohort Studies↗
PubMed1998

Artificial neural networks and logistic regression as tools for prediction of survival in patients with Stages I and II non-small cell lung cancer.

The prognosis of patients with Stage I and II non-small cell lung cancer (NSCLC) can be estimated but cannot be definitively ascertained by use of current clinicopathologic criteria and tumor marker studies. The potential value of probabilistic neural networks (NNs) with genetic algorithms and multivariate logistic regression to predict the survival of NSCLC patients has not been previously evaluated. Multiple prognostic factors (age, sex, cell type, stage, tumor grade, smoking history, and immunoreactivity to c-erbB-3, bcl-2, Glut1, Glut3, retinoblastoma gene and p53 were correlated with 5-year survival in 63 patients with Stage I or II NSCLC, treated solely by surgical excision at Baylor Medical College, Houston, Texas. Several probabilistic NNs with genetic algorithm models were developed using the prognostic features as input neurons and survival at 5 years (free of disease/dead of disease) as output neurons. The probabilistic NN yielded excellent classification rates for dependent variable survival. The best model was trained with 52 cases and classified all 11 "unknown" test cases correctly. Several statistically significant logistic regression models were fitted using 50 cases to build the models and 13 cases as "hold-out" test cases. These multivariate statistical models provide various cutoff values that predict/classify the probability of survival at 5 years. In conclusion, probabilistic NNs and logistic regression models can be useful in estimating the prognosis of patients with Stage I and II NSCLC using multiple clinicopathologic and molecular variables. These multivariate predictive models need to be validated with much larger groups of patients to assess their potential clinical value.

Adult↗
PubMed1998

Low and maximally phosphorylated levels of the retinoblastoma protein confer poor prognosis in newly diagnosed acute myelogenous leukemia: a prospective study.

A prior retrospective study suggested that the level of retinoblastoma protein (RB) expression was prognostic for survival in acute myelogenous leukemia (AML). Individuals with no/low RB protein expression were considered to have loss of RB function, and those with maximally phosphorylated (maxphos) RB were also felt to have nonfunctional RB. To confirm this, we prospectively investigated whether the level of RB expression was prognostic in AML in a larger cohort of patients. RB level was measured by Western blot and immunohistochemical analysis on peripheral blood samples from 210 newly diagnosed AML patients. Patients were divided into three groups based on the level of RB protein expression (i.e., no or low, elevated, and maxphos) or into two groups on the basis of presumed RB function, altered function (AF-RB, low and maxphos RB), versus normal function (NF-RB, elevated RB). By combined results of Western blot and immunohistochemical analysis, 20%, 65%, and 15% of patients had low, elevated, and maxphos RB, respectively. Most patients with acute promyelocytic leukemia (APL) with a French-American-British classification of M3 were in the low RB group, likely reflecting a lower proliferative rate of promyelocytes. Analysis was performed with and without these APL patients. The median survival was significantly shorter for both patients with low RB expression (48 weeks, P = 0.05, including APL patients; 34 weeks, corrected P = 0.008, with APL patients excluded) and maxphos RB expression (51 weeks, P = 0.007) compared to those with elevated RB expression (122 weeks including and 98 weeks excluding APL patients). Differences were greatest among patients with nonfavorable prognosis cytogenetics (median survival, 34 weeks versus 85 weeks; corrected P = 0.001 for AF-RB versus NF-RB). Remission duration was also significantly shorter for non-APL patients with AF-RB versus NF-RB (median survival, 36 weeks versus not reached; corrected P = 0.02). In multivariate analyses, including cytogenetics, performance status, age, antecedent hematological disorder, and RB status, with and without APL patients included, no/low and maxphos-RB protein expression were independent predictors for poorer survival. This prospective study confirms that the level of expression of RB is a strong prognostic factor in AML, with an inferior survival experience being associated with no/low RB and maxphos RB expression. Therefore, therapeutic decisions based on the level of RB expression may be indicated, and protocols to incorporate this are currently under development.

Adolescent↗
PubMed1997

Retinoblastoma protein expression and radiation response in muscle-invasive bladder cancer.

PURPOSE: The retinoblastoma protein (pRB) is a key regulator of the G1 cell cycle checkpoint and has been implicated as having a role in G1 arrest and apoptosis induced by radiation damage. In this report we examine the association between pRB expression and radiation response in patients treated between 1960 and 1983 with preoperative radiotherapy (50 Gy in 25 fractions) followed 4-6 weeks later by radical cystectomy. The correlation of pRB to patient outcome and how this relationship is complimentary to that seen with p53 staining status is also described. METHODS AND MATERIALS: Immunohistochemical staining of pRB and p53 in paraffin-embedded tumor sections using WL-1 anti-RB and DO1 anti-p53 antibodies was considered adequate in 98 and 97 pretreatment tumor samples, respectively. There were 46 patients with clinical Stage T2, 28 with Stage T3a, and 24 with Stage T3b disease. The median age was 62 years and follow-up for those living was 85 months. RESULTS: Staining for pRB was negative in 30% of the cases. Correlations were observed between pRB negativity and high pretreatment apoptosis level (p = 0.06), locally advanced clinical stage (p = 0.01), increased clinical-to-pathologic downstaging (p = 0.014), and more pathologic complete responses (Path-CRs; p = 0.019). Several other factors were tested and were not associated with pRB status, including p53 expression. RB status was the only pretreatment prognostic factor in the univariate analyses that correlated with downstaging and was independently associated with Path-CR using multivariate logistic regression. Despite these significant relationships, no correlations with patient outcome were observed when the entire cohort was analyzed. Restriction of the analyses to Stage T3b patients, however, revealed that pRB negativity predicted for enhanced distant metastasis freedom (p = 0.006, log rank) and overall survival (p = 0.02). The overexpression of p53 also correlated with distant metastasis freedom and overall survival in Stage T3b patients. Patient outcome was best when RB negative and p53 negative staining were seen. CONCLUSION: Our results indicate that loss of RB function as measured by immunohistochemical staining is the strongest correlate of radiation response thus far recognized. Loss of RB expression also predicted for poor outcome in Stage T3b patients, which appeared to compliment the finding of normal p53 expression. While normal RB protein expression is usually associated with better patient outcome, other series have not examined patients treated with radiotherapy. The absence of pRB may be a useful marker for selecting patients for bladder preservation with radiotherapy, particularly when wild-type p53 is present.

Adult↗