Reduced immunohistochemical PTEN staining is associated with higher progression rate and recurrence episodes in non-invasive low-grade papillary urothelial carcinoma of the bladder.

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Non-invasive low-grade papillary urothelial carcinoma (NILGPUC) of the bladder is regarded as a relatively indolent disease. However, its propensity for frequent recurrences constitutes a major clinical problem. Additionally, there is a progression risk of 10-15% to either a higher grade and/or a higher stage disease in these tumors. The molecular factors that will predict recurrence and progression in low-grade pTa bladder carcinoma have not yet been elucidated. Herein, we investigated the association of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) alterations with recurrence and progression in NILGPUC using immunohistochemistry. Eighty-one cases of bladder cancer initially diagnosed as NILGPUC in a single institution with follow-up were encountered after searching medical records. Tissue microarrays (TMA) that contained both tumor and non-neoplastic mucosa from each case were constructed using paraffin blocks of transurethral resections. Sections from TMA blocks were stained immunohistochemically for PTEN protein and were evaluable in 76 cases. Any absence of staining was recorded and correlated with clinical findings. Ten patients (13.2%) showed progression and 41 (53.9%) showed recurrence. Reduced PTEN expression was observed in 29 cases (38.1%). Cases with reduced PTEN had higher progression rate compared to cases with intact PTEN (p = 0.026). Tumor relapse was more frequent in cases with reduced PTEN (65.5 vs 46.8%), but this difference was not statistically significant (p = 0.112). On the other hand, decreased PTEN expression was associated with higher number of recurrence episodes (p = 0.002). PTEN seems to have a link with the disease course in NILGPUC of the bladder.