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Validation of a Rapid Method to Quantify Apoptosis in Superficial Bladder Cancer
PRINCIPLES OF ONCOLOGY, AND TUMORS OF BLADDER, PENIS AND URETHRA
617
a series of nonrandom genetic alterations affecting a particular set of oncogenes and tumor-suppressor genes. Because the modality of therapy for patients with bladder neoplasms primarily depends on morphological evaluation and clinical staging, the diagnosis cames significant consequences. However, it is well known that morphologically similar tumors presenting in any assigned stage may behave in radically different fashions, which seriously hampers the physician’s ability accurately to predict clinical behavior in a given case. Recent studies have shown that inactivation of certain tumor-suppressor genes, such as RB and TP53, occur in bladder tumors that have a more aggressive clinical outcome and poor prognosis. In the present paper we review the molecular abnormalities associated with these dominant and recessive genes in bladder cancer and discuss the potential clinical use of their detection. The implementation of objective predictive assays to identify these alterations in clinical material will enhance our ability to assess tumor biological activities and to design effective treatment regimens. The need now is to translate this newly developed scientific knowledge into diagnostic and therapeutic strategies, which in turn will enhance the quality of life and prolong the survival of patients with bladder cancer.
Editorial Comment: The authors review the current status of molecular changes in various forms of bladder cancer and how these changes may indicate the pathway of tumor development, the likelihood of progression and reasons for failure of different treatments in association with tumor progression and metastasis. Genetic changes in various forms of transitional cell cancer appear to have an association with the likelihood of a particular type of activity. The predominant correlation that has been observed has been between the expression of p53 (representing a defect in chromosome 17)and a concomitant biological aggressiveness.This finding is being used to design clinical protocols that determine treatment on the basis of whether p53 is expressed. Although validation of such observations is needed, continued study will undoubtedly permit the generation of profiles by which urothelial malignancies can be classified and treatments selected on the basis of the predicted biological behavior. Michael J. Droller, M.D.
Validation of a Rapid Method to Quantify Apoptosis in Superficial Bladder Cancer J. D. KELLY,P. W. HAMILTON, K. E. WILLIAMSON, H. P. WEIR,D. T. MCMANUS, P. F. BANE AND S. R. JOHNSTON, Department of Urology, Belfast City Hospital, and Departments of Pathology and Surgery, Queen’s University of Belfast, Belfast, Northern Ireland Brit. J. Urol., 8 0 927-932, 1997 Objectives: To derive and validate a rapid method for calculating apoptotic indices in superficial transitional cell carcinoma (TCC) as a measure of chemosensitivity to mitomycin. Materials and methods: Apoptotic cells, identified by light microscopy in 20 superficial TCC specimens, were expressed as an index of the total tumour cell population within defined fields. For a given field, the total cell population was estimated by: (i)an exhaustive count of the total number of cells in the field and (ii) an abbreviated method in which the number of cells in a subfield was multiplied to provide an estimate of the total field number. Field and specimen estimates were compared using agreement statistics and the intra- and inter-observer reproducibility of apoptotic indices calculated. Results: Cellularity and apoptotic indices obtained using method (ii)were correlated significantly with the true cell counts (P <0.001). Agreement statistics showed that only 9.4% of counts fell outside two standard deviations (SD) from the mean in field analysis, and only 10% of counts fell outside 2 SD from the mean in specimen analysis. There was a fivefold variation in tumour cell counts among individual fields. Conclusions: The reported variation in cellularity among fields shows that the calculation of apoptosis must use the total cell population as the reference. The limits of agreement for the estimated and true cell counts are small enough to be confident that the shorter method to estimate cellularity can be used in place of counting all cells. Editorial Comment: This study reveals what appears to be a reliable and reproducible method in quantifying apoptosis in superficial transitional cell tumors. The value of this method would be to gauge the efficacy of various intravesical treatments and their effect in the induction of apoptosis in recurrent transitional cell carcinoma. A set of morphological criteria for the identification of apoptotic cells is presented. Validation of the method is also included with a discussion of interobserver variability. The authors considered the difficulty associated with obtaining an assessment of a l l of the tumor cells in a particular tumor, variability of cellularity within a particular field and the possible heterogeneity of the apoptotic phenomenon. They compared the method of estimating cellularity with the more tedious method of actually counting cells, and found little difference in cell counts between the 2 methods. It remains to be seen whether the broader applicability of this method in assessing the efficacy of intravesical treatments will validate it. The demonstration of clinical therapeutic outcomes on the basis of measurements of induced apoptosis will be even more important. Michael J. Droller, M.D.
617
a series of nonrandom genetic alterations affecting a particular set of oncogenes and tumor-suppressor genes. Because the modality of therapy for patients with bladder neoplasms primarily depends on morphological evaluation and clinical staging, the diagnosis cames significant consequences. However, it is well known that morphologically similar tumors presenting in any assigned stage may behave in radically different fashions, which seriously hampers the physician’s ability accurately to predict clinical behavior in a given case. Recent studies have shown that inactivation of certain tumor-suppressor genes, such as RB and TP53, occur in bladder tumors that have a more aggressive clinical outcome and poor prognosis. In the present paper we review the molecular abnormalities associated with these dominant and recessive genes in bladder cancer and discuss the potential clinical use of their detection. The implementation of objective predictive assays to identify these alterations in clinical material will enhance our ability to assess tumor biological activities and to design effective treatment regimens. The need now is to translate this newly developed scientific knowledge into diagnostic and therapeutic strategies, which in turn will enhance the quality of life and prolong the survival of patients with bladder cancer.
Editorial Comment: The authors review the current status of molecular changes in various forms of bladder cancer and how these changes may indicate the pathway of tumor development, the likelihood of progression and reasons for failure of different treatments in association with tumor progression and metastasis. Genetic changes in various forms of transitional cell cancer appear to have an association with the likelihood of a particular type of activity. The predominant correlation that has been observed has been between the expression of p53 (representing a defect in chromosome 17)and a concomitant biological aggressiveness.This finding is being used to design clinical protocols that determine treatment on the basis of whether p53 is expressed. Although validation of such observations is needed, continued study will undoubtedly permit the generation of profiles by which urothelial malignancies can be classified and treatments selected on the basis of the predicted biological behavior. Michael J. Droller, M.D.
Validation of a Rapid Method to Quantify Apoptosis in Superficial Bladder Cancer J. D. KELLY,P. W. HAMILTON, K. E. WILLIAMSON, H. P. WEIR,D. T. MCMANUS, P. F. BANE AND S. R. JOHNSTON, Department of Urology, Belfast City Hospital, and Departments of Pathology and Surgery, Queen’s University of Belfast, Belfast, Northern Ireland Brit. J. Urol., 8 0 927-932, 1997 Objectives: To derive and validate a rapid method for calculating apoptotic indices in superficial transitional cell carcinoma (TCC) as a measure of chemosensitivity to mitomycin. Materials and methods: Apoptotic cells, identified by light microscopy in 20 superficial TCC specimens, were expressed as an index of the total tumour cell population within defined fields. For a given field, the total cell population was estimated by: (i)an exhaustive count of the total number of cells in the field and (ii) an abbreviated method in which the number of cells in a subfield was multiplied to provide an estimate of the total field number. Field and specimen estimates were compared using agreement statistics and the intra- and inter-observer reproducibility of apoptotic indices calculated. Results: Cellularity and apoptotic indices obtained using method (ii)were correlated significantly with the true cell counts (P <0.001). Agreement statistics showed that only 9.4% of counts fell outside two standard deviations (SD) from the mean in field analysis, and only 10% of counts fell outside 2 SD from the mean in specimen analysis. There was a fivefold variation in tumour cell counts among individual fields. Conclusions: The reported variation in cellularity among fields shows that the calculation of apoptosis must use the total cell population as the reference. The limits of agreement for the estimated and true cell counts are small enough to be confident that the shorter method to estimate cellularity can be used in place of counting all cells. Editorial Comment: This study reveals what appears to be a reliable and reproducible method in quantifying apoptosis in superficial transitional cell tumors. The value of this method would be to gauge the efficacy of various intravesical treatments and their effect in the induction of apoptosis in recurrent transitional cell carcinoma. A set of morphological criteria for the identification of apoptotic cells is presented. Validation of the method is also included with a discussion of interobserver variability. The authors considered the difficulty associated with obtaining an assessment of a l l of the tumor cells in a particular tumor, variability of cellularity within a particular field and the possible heterogeneity of the apoptotic phenomenon. They compared the method of estimating cellularity with the more tedious method of actually counting cells, and found little difference in cell counts between the 2 methods. It remains to be seen whether the broader applicability of this method in assessing the efficacy of intravesical treatments will validate it. The demonstration of clinical therapeutic outcomes on the basis of measurements of induced apoptosis will be even more important. Michael J. Droller, M.D.