Thymidine phosphorylase levels as a prognostic factor in renal cell carcinoma

The dual role of thymidine phosphorylase in cancer development and chemotherapy

Thymidine phosphorylase (TP), also known as "platelet-derived endothelial cell growth factor" (PD-ECGF), is an enzyme, which is upregulated in a wide variety of solid tumors including breast and colorectal cancers. TP promotes tumor growth and metastasis by preventing apoptosis and inducing angiogenesis. Elevated levels of TP are associated with tumor aggressiveness and poor prognosis. Therefore, TP inhibitors are synthesized in an attempt to prevent tumor angiogenesis and metastasis. TP is also indispensable for the activation of the extensively used 5-fluorouracil prodrug capecitabine, which is clinically used for the treatment of colon and breast cancer. Clinical trials that combine capecitabine with TP-inducing therapies (such as taxanes or radiotherapy) suggest that increasing TP expression is an adequate strategy to enhance the antitumoral efficacy of capecitabine. Thus, TP plays a dual role in cancer development and therapy: on the one hand, TP inhibitors can abrogate the tumorigenic and metastatic properties of TP; on the other, TP activity is necessary for the activation of several chemotherapeutic drugs. This duality illustrates the complexity of the role of TP in tumor progression and in the clinical response to fluoropyrimidine-based chemotherapy.

Thymidine phosphorylase as a prognostic factor in renal cell carcinoma

The purpose of the current study was to clarify further the clinicopathologic significance of thymidine phosphorylase (TP) expression in renal cell carcinoma (RCC). TP expression was evaluated with immunohistochemistry assays using monoclonal anti-TP antibody in formalin-fixed, paraffin-embedded archived specimens of 70 patients with radically operated nonmetastatic RCC (M0 by TNM classification). Semiquantitative analysis, using a scoring system for staining pattern and staining intensity was used. Univariate analysis showed that the characteristics that carried the prognostic significance for survival were age as continuous characteristic (chi-square log-rank test P = 0.0121), TP expression (P = 0.0061), histologic grade (P < 0.0001), and stage (P = 0.0244). In multivariate analysis (by Cox proportional hazards regression analysis), the factors significant for survival were age (HR 1.09; 95% CI 1.03-1.14), stage (HR 2.76; 95% CI 1.27-6.07), and histologic grade (HR 7.91; 95% CI 2.11-29.7), TP did not show independent significant value (HR 0.68; 95% CI 0.19-2.50). However, TP had strong correlation with histologic grade (P = 0.818). In conclusion, TP expression level in RCC is strongly correlated with histologic grade, which is one of well-known prognostic factors in RCC, but TP had no independent prognostic value.

High levels of thymidine phosphorylase as an independent prognostic factor in renal cell carcinoma

BACKGROUND

We investigated whether thymidine phosphorylase (TP) protein level in renal cell carcinoma (RCC) correlates with clinicopathological characteristics and clinical outcomes.

METHODS

TP protein level was measured in 116 RCC specimens and in 90 non-neoplastic kidney tissues using a sandwich-type enzyme-linked immunosolvent assay.

RESULTS

The median TP protein level in RCC tissues was 9.76-fold (range, 3.2-933.9) higher than those in non-neoplastic kidney tissues (P < 0.0001). TP protein level was correlated with T classification, histological grade and mode of infiltration. TP as a prognostic variable was studied using a logistic regression model. TP at higher levels (128 U/mg protein or greater) would play a role as an independent prognostic factor (odds ratio, 13.73; 95% confidence interval, 2.09-90.41; P = 0.0064).

CONCLUSION

TP at high levels can be regarded as an unfavorable independent prognostic factor. These results may pave a way for a novel approach to effective treatment of RCC.

Renal cell carcinoma: new prognostic factors?

PURPOSE OF REVIEW

There are limited independent predictors of survival in patients with renal cell carcinoma. Factors related to the tumor, host and treatment may help us to predict prognosis to a certain extent. Prognostic indicators would enable selection of patients who can benefit from adjuvant therapy and thus should be enrolled in clinical trials. This review highlights developments in the identification of current prognosticators for patients with renal cell carcinoma.

RECENT FINDINGS

Tumor stage, grade and patient-performance status are the known prognostic indicators in renal cell carcinoma. Besides these parameters, many molecular and cytogenetic markers were evaluated recently. Unfortunately, none of these parameters appear to be a better predictive prognostic factor than the usual staging and grading. Therefore, efforts to identify new markers for tumor proliferation and progression are still ongoing. It was recently reported that low carbonic anhydrase 9 staining may be an independent poor prognostic factor in patients with renal cell carcinoma. Moreover, there is increasing interest in prognostic indices and predictive algorithms for survival. Staging systems that combine the pathological features with additional prognostic variables have been constructed to predict outcome. The UCLA Integrated Staging System seems to be superior to staging alone in differentiating patients' survival.

SUMMARY

Although the literature reviewed contains numerous promising clinical, histological, molecular and cytogenetic parameters, none of them has yet been shown to have an independent prognostic value