[Should we systematically screen for Lynch syndrome in patients with upper urinary tract carcinoma?].

OBJECTIVE: The data describing the urologic extracolonic cancers associated with Lynch syndrome (hereditary non-polyposis colorectal cancer [HNPCC]) are variable. The aim of our study was to establish the frequency of mutations in mismatch repair (MMR) genes in patients with upper urinary tract transitional cell carcinoma (UUT-TCC) and to evaluate the clinical benefits of a systematic screening.

METHODS: Specimen blocks were obtained from 146 patients treated for UUT-TCC in our center. Clinicopathological characteristics and survival data of patients were collected (median follow-up = 42.5 months). Immunohistochemistry was performed by tissue microarray (TMA), in order to detect mutations in mismatch repair genes. Results obtained after TMA analysis were confirmed at a molecular level by microsatellite instability (MSI) analysis.

RESULTS: Mutations in mismatch repair genes were detected in seven patients (4.8%) at immunohistochemistry screening, and confirmed by MSI analysis for five of them (3.4%). Clinicopathological characteristics and survival data did not differ significantly in patients with instability compared with patients without. After a median follow-up of 42.5 months, none of them experienced a new HNPCC manifestation.

CONCLUSION: The frequency of mutations in mismatch repair genes in UUT-TCC was very low, with a good accuracy of immunohistochemistry. Systematic screening should not be proposed in daily practice.