Metastatic papillary renal cell carcinoma in the era of targeted therapy - a retrospective study from three European academic centres

Background: Metastatic papillary renal cell carcinoma (mPRCC) is understudied. The disease is often aggressive and specific treatment options are lacking.Patients and methods: mPRCC patients (n=86) referred to three academic centres in Sweden and Germany in the years 2005-2015 were retrospectively identified from medical records. Statistical analyses included Kaplan-Meier curves and calculation of Cox proportional hazards, generating hazard ratios with 95% confidence intervals. The aim of the study was to evaluate overall survival (OS) of mPRCC patients treated outside of clinical trials in the era of targeted agents (TA) and to identify clinically useful prognostic factors.Results: Median OS of all mPRCC patients was 11.2 months. TA were used in 77% of the patients and associated with younger age and better Eastern Cooperative Oncology Group performance status (PS). Brain metastases were common (28%). Patients with synchronous or metachronous metastases had similar OS. Variables independently associated with risk of death included age 60 years, worse PS and 3 metastatic sites. The MSKCC criteria did not provide additional prognostic information. A subgroup analysis of TA-treated patients revealed an association of lymph node metastasis with risk of death in addition to the other prognostic factors.Conclusion: OS in mPRCC remained short in the era of targeted agents. Age, PS, and number of metastatic sites provided independent prognostic information.