Survivin: a promising tumor biomarker.

Survivin is a 16.5 kDa protein overexpressed in almost all malignancies but rarely detected in normal differentiated adult tissues. Functionally, survivin has been shown to inhibit apoptosis, promote cell proliferation and enhance angiogenesis. Consistent with its role in these processes, survivin has been shown to play a key role in cancer progression. Because of the large difference in expression between normal and malignant tissue and its causal role in cancer progression, survivin is currently undergoing intensive investigation as a potential tumor marker. Emerging data suggests that measurement of survivin can aid the early diagnosis of bladder cancer, determine prognosis in multiple cancer types and predict response to diverse anti-cancer therapies. These preliminary findings on the diagnostic, prognostic and predictive potential of survivin should now be confirmed in large prospective trials. Furthermore, assays for the measurement of survivin should be simplified, standardized and evaluated in external quality assurance schemes.