Abstract 476: Differential prognostic value of MYC immunohistochemistry in papillary RCC subtypes

Introduction The histomorphological classification of type 1 and type 2 papillary renal cell carcinomas (pRCCs) has substantially improved the prognostication of patients’ long-term outcome. We previously established microRNA (miRNA) expression profiles of type1 and type 2 pRCCs and, based upon the results, hypothesize a differential expression of the MYC proto-oncogene in pRCCs. Material and methods An multi-institutional tissue microarray with more than 200 histomorphological classified pRCCs was acquired from the PANZAR consortium. Immunohistochemistry for MYC, the MYC-induced nuclear antigen MINA53 and Ki67 was performed. The prognostic value for patients’ long-term survival was examined using uni- and multivariate survival models. Results As expected, a pRCC type 2 morphology was associated with reduced overall and cancer-specific survival. Interestingly, pRCCs with a mixed type 1/2 morphology showed an even worse clinical outcome. When combining the pRCC morphology and immunohistochemical staining, only the combination of morphology and MYC staining patterns was able to further sub-stratify the group of pRCC type 1 tumors in a good and worse prognosis group. None of the patients with pRCC1 tumors and the favorable MYC staining pattern (>44% of all pRCC type 1 tumors) suffered a tumor-related death. Patients with pRCC type 1 tumors and the adverse MYC staining pattern had an 4.5-fold elevated risk of death (multivariate corrected for pathological tumor stage). Conclusions Although a pRCC type 1 histomorphology is regarded as a favorable prognostic factor, associated with good clinical outcome, still patients die of tumor-related causes. We conclude, that in particular for patients with pRCC type 1 tumors, MYC immunohistochemistry is able to provide additional prognostic information for a sub-stratification of this patient population. This knowledge could be used for the establishment of risk-stratified follow-up schemes for patients after surgical treatment. Citation Format: Julia Bellut, Simone Bertz, Elke Nolte, Christine Stoehr, Iris Polifka, Edwin Herrmann, Rudolf Jung, Arndt Hartmann, Bernd Wullich, Helge Taubert, Sven Wach. Differential prognostic value of MYC immunohistochemistry in papillary RCC subtypes. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 476.