Correspondence

p53 and Bladder Cancer

N Engl J Med 1995; 332:957-958April 6, 1995

Article

To the Editor:

Esrig and colleagues (Nov. 10 issue)1 demonstrate that the immunohistochemical detection of p53 protein in bladder-tumor cells predicts the progression of disease independently of the tumor stage and histologic grade and correlates with an increased risk of recurrent tumor and mortality. This work, combined with recent advances such as the purification of angiostatin, an endogenous inhibitor of tumor angiogenesis,2 foreshadows a new approach to identifying patients at high risk for recurrence and metastases, especially when lymph nodes appear to be uninvolved and when surgical resection of the primary tumor suggests an initial cure. Such patients may benefit from early, aggressive adjuvant treatment of the cancer.

A growing body of evidence suggests the clinical usefulness of markers relevant to tumor angiogenesis. Sensitive assays can detect angiogenic cytokines such as basic fibroblast growth factor and vascular endothelial-cell growth factor, which correlate with angiogenic activity and decreased survival.3 The intensity of angiogenesis (as indicated by the histologic microvessel count in the tumor-biopsy specimen) is a prognostic marker for a variety of solid tumors, including tumors of the colon, lung, brain, breast, and prostate, and for some nonsolid tumors, such as multiple myeloma.

The wild-type p53 gene product is a polypeptide identical to thrombospondin, an antiangiogenic protein associated with tumor-suppressive activity. Deletion or mutation of the p53 gene in cells derived from patients with the Li–Fraumeni syndrome results in the loss of antiangiogenic activity and progression of tumorigenesis.4 Transitional-cell bladder carcinomas are highly vascularized tumors. Patients with bladder cancer have elevated levels of angiogenic cytokines in urine.5 Therefore, the association, reported by Esrig et al., between mutated p53 and recurrent disease may reflect the loss of suppression of tumor angiogenesis.

Given the antiangiogenic property of the wild-type p53 gene, it would be extremely interesting to go back to the cell blocks used by Esrig et al. and see whether the presence of nuclear p53 (loss of antiangiogenic activity) correlates with the microvessel count (tumor angiogenesis); whether the microvessel count correlates with recurrence, metastases, or mortality; and whether the presence of thrombospondin detected in specimens by immunohistochemical methods correlates with survival. These correlations would suggest a fundamental mechanism for the progression of bladder carcinoma, which in turn would suggest a rationale for antiangiogenic treatment of patients with bladder cancer.

William W. Li, M.D.
Vincent W. Li, M.D.
Massachusetts General Hospital, Boston, MA 02114

Dimitris Tsakayannis, M.D.
Children's Hospital, Boston, MA 02115

5 References

1
Esrig D, Elmajian D, Groshen S, et al. Accumulation of nuclear p53 and tumor progression in bladder cancer. N Engl J Med 1994;331:1259-1264
Full Text | Web of Science | Medline

2
O'Reilly MS, Holmgren L, Shing Y, et al. Angiostatin: a novel angiogenesis inhibitor that mediates the suppression of metastases by a Lewis lung carcinoma. Cell 1994;79:315-328
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3
Li VW, Folkerth RD, Watanabe H, et al. Microvessel count and cerebrospinal fluid basic fibroblast growth factor in children with brain tumours. Lancet 1994;344:82-86
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4
Dameron KM, Volpert OV, Tainsky MA, Bouck N. Control of angiogenesis in fibroblasts by p53 regulation of thrombospondin-1. Science 1994;265:1582-1584
CrossRef | Web of Science | Medline

5
Nguyen M, Watanabe H, Budson AE, Richie JP, Folkman J. Elevated levels of the angiogenic peptide basic fibroblast growth factor in urine of bladder cancer patients. J Natl Cancer Inst 1993;85:241-242
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To the Editor:

Esrig et al. report that the accumulation of p53 protein predicts recurrence and decreased overall survival in patients with transitional-cell carcinoma of the bladder. However, additional statistical analysis could modify these findings. Esrig et al. considered deaths due to any cause to represent treatment failures, which may be arguable, since one would normally censor deaths unrelated to the cancer or its complications. The authors claim that they did “a multivariable analysis,” but it appears that they performed only a stratified analysis according to grade, pathological stage, and presence or absence of lymph-node metastases, not a multivariable analysis. A Cox proportional-hazards model could be used to test the use of p53 protein accumulation as a predictive factor independent of grade, stage, therapeutic protocol, and so forth, with incorporation of the time variables and censoring. Instead, the authors used the Kaplan–Meier technique and the log-rank test. It would be useful to treat p53 protein accumulation as a continuous variable as well as a dichotomous variable. Relative risks and their 95 percent confidence intervals and the linear-trend test could be used to show the influence of the variable on the outcomes. These additional analyses would certainly provide reassurance, even if they did not modify the results materially.

Xueping Xing, M.D., Ph.D.
Columbia University, New York, NY 10032

To the Editor:

Esrig and colleagues found that extraordinarily large amounts of the p53 protein (mostly mutated forms) in the nuclear region of more than 10 percent of examined cells from resected bladder tumors indicate a bleak prognosis with respect to both recurrent disease and long-term survival. Many of the mutated variants of p53 are unusually resistant to intracellular biodegradation and thus accumulate in many times higher concentrations than does the wild-type analogue, and sustained high p53 concentrations connote the wild-type p53 gene mutation quite reliably. Because of their findings, Esrig et al. recommend adjuvant therapy, including chemotherapy and radiotherapy, for patients found to have extraordinarily high concentrations of (mutant) p53 in resected bladder tissue.

However, basic theoretical considerations, underscored by much recent experimental data, do not support this recommendation, at least for the major adjuvant therapies. Wild-type p53 apparently must be expressed in neoplastic cells for these cells to respond to clinically tolerable doses of either radiotherapy or chemotherapy. Neoplastic cells that produce no or only mutant p53 have been found to be as resistant as their non-neoplastic analogues to either ionizing radiation or cytotoxic chemical agents.1,2

Lowell L. Wood, Ph.D.
Hoover Institution, Stanford, CA 94305-6010

2 References

1
Lowe SW, Ruley HE, Jacks T, Housman DE. p53-Dependent apoptosis modulates the cytotoxicity of anticancer agents. Cell 1993;74:957-967
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2
Lowe SW, Schmitt EM, Smith SW, Osborne BA, Jacks T. p53 Is required for radiation-induced apoptosis in mouse thymocytes. Nature 1993;362:847-849
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Author/Editor Response

The authors reply:

To the Editor: Li and colleagues discuss a topic of growing interest — that is, the relation between alterations in p53 and tumor angiogenesis.1 We have now shown that microvessel counts are strongly associated with recurrence of disease and length of survival in patients with bladder cancer.2 Furthermore, there is a significant correlation between increased nuclear accumulation of p53 and increased microvessel counts.3 Studies examining the relation among p53 alterations, microvessel counts, and the expression of thrombospondin 1 are now under way in our laboratory. One of the mechanisms of p53-mediated tumor progression may be the promotion of an angiogenic response, which could have therapeutic implications.

With regard to Dr. Xing's comments, we believe that the best measures of outcome are recurrent bladder cancer and overall survival. Deciding that a death is or is not due to bladder cancer can be problematic and may introduce bias. However, in the population we reported on, the association between nuclear p53 accumulation and death due to bladder cancer was significant (P<0.001) on the basis of the log-rank test.

To determine whether nuclear accumulation of p53 provides information about outcome independent of that provided by stage and grade (the two most important variables currently in standard use), a multivariable analysis with the stratified log-rank test is as appropriate as the Cox proportional-hazards model. In our study, the two methods of analysis yielded virtually identical results. On the basis of the Cox model, the relative risk of death for patients with p53 nuclear accumulation was 2.19 times that for patients with no detectable p53 expression (P<0.001); on the basis of log-rank calculations, the relative risk was 2.00 (P<0.001).

Finally, although the extent of nuclear reactivity in tumor cells was divided into four categories (0, 1 to 9, 10 to 49, and 50 to 100 percent positive nuclei), the patients were divided into two groups (those with less than 10 percent positive tumor-cell nuclei and those with 10 percent or more) on the basis of our previous study demonstrating the association between nuclear accumulation of p53 and mutations in the gene.4 Thus, the basis for the classification of the patients was whether or not there was a detectable abnormality in the results of the p53 immunohistochemical test. When the four groups of patients were compared, those with no or very little p53 expression (0 or 1 to 9 percent) had virtually identical (low) rates of recurrent disease; the two groups with higher levels of p53 expression (10 to 49 and 50 to 100 percent) had similar (high) recurrence rates on the basis of Kaplan–Meier plots and the log-rank rest. Similar results were obtained for survival.

We are aware of the data, noted by Dr. Wood, on p53 alterations in tumors and response (or resistance) to radiation and chemotherapeutic agents. Bladder tumors with p53 alterations may be less responsive to adjuvant therapies (although this has not been demonstrated in vivo), but our results clearly indicate a high rate of progression despite radical surgery, even when the tumors are pathologically confined to the bladder. Thus, our recommendation was based on the fact that for many patients with bladder cancer and p53 alterations, adjuvant therapy may be the best remaining option. The response of p53-altered tumors to the wide spectrum of antineoplastic therapies now available remains to be seen.

Richard J. Cote, M.D.
Donald G. Skinner, M.D.
Peter A. Jones, Ph.D.
University of Southern California School of Medicine, Los Angeles, CA 90033

4 References

1
Dameron KM, Volpert OV, Tainsky MA, Bouck N. Control of angiogenesis in fibroblasts by p53 regulation of thrombospondin-1. Science 1994;265:1582-1584
CrossRef | Web of Science | Medline

2
Bochner BH, Cote RJ, Groshen S, et al. Tumor angiogenesis is an independent prognostic indicator in invasive transitional cell carcinoma of the bladder. J Urol 1995;153:46A-46A abstract.

3
Bochner BH, Nichols PW, Esrig D, et al. Relationship between p53 and tumor angiogenesis in invasive transitional cell carcinoma (TCC) of the bladder. Proc Am Assoc Cancer Res 1995;36:91-91 abstract.

4
Esrig D, Spruck CH III, Nichols PW, et al. p53 Nuclear protein accumulation correlates with mutations in the p53 gene, tumor grade, and stage in bladder cancer. Am J Pathol 1993;143:1389-1397
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