Upper tract urothelial carcinoma (UTUC) may arise in the setting of hereditary non-polyposis colorectal cancer (Lynch syndrome [LS]) or sporadically. Variable frequencies of microsatellite instability (MSI) were found in UTUC. For advanced solid MSI tumors, targeted therapy with programmed death-ligand 1 inhibitors is available. Therefore, we aimed to determine the prevalence of mismatch repair (MMR) protein loss and MSI in UTUC using a tissue microarray approach and further molecular and correlation analysis.
We studied the immunohistochemical expression of MLH1, MSH2, MSH6, and PMS2 on tissue microarrays containing formalin-fixed, paraffin-embedded samples of 128 patients with UTUC. MSI analysis was performed in 79 cases with deficient MMR protein expression, and/or in patients aged 60 years and below, and/or other tumors possibly related to LS.
Loss of MMR protein expression was seen in 24 (18.8%) of 128 cases. MSI analysis revealed MSI-high in 29, MSI-low in 7 cases. The Fisher exact test demonstrated significant differences between MSI and loss of MMR protein expression, clinically possible LS, tumor growth pattern, inverted growth pattern, and death (P < .001, P < .001, P = .002, P = .003, and P = .033, respectively). MSI does not appear to influence survival (overall and progression-free), but there was a significant shorter progression-free survival in MSI-high versus MSS patients who had received chemotherapy.
The frequency of MSI in UTUC was 36 (28.1%) of 128 patients with a good accuracy of immunohistochemistry. In daily practice, MSI screening especially is recommended in patients with advanced UTUC and inverted papillary tumor growth pattern with the aim of screening patients for possible targeted therapy.
Clinical genitourinary cancer. 2020 Mar 13 [Epub ahead of print]
Björn Schneider, Änne Glass, Sandra Jagdmann, Maja Hühns, Jessica Claus, Heike Zettl, Desiree-Louise Dräger, Matthias Maruschke, Oliver W Hakenberg, Andreas Erbersdobler, Annette Zimpfer
Institute of Pathology, University Medicine Rostock, Rostock, Germany. Electronic address: ., Institute for Biostatistics and Informatics in Medicine, University Medicine Rostock, Rostock, Germany., Institute for Medical Immunology, Charité University Medicine, Berlin, Germany., Institute of Pathology, University Medicine Rostock, Rostock, Germany., Rostock Cancer Registry, University Medicine Rostock, Rostock, Germany., Department of Urology, University Medicine Rostock, Rostock, Germany., Department of Urology, University Medicine Rostock, Rostock, Germany; Department of Urology, HELIOS Hanseklinikum Stralsund, Stralsund, Germany.