Metastatic papillary renal cell carcinoma: A retrospective study from two large academic centers in Sweden.

Abstract

535 Background: Non-clear cell renal cell carcinoma (nccRCC) constitute about 10-15% of all metastatic renal cell carcinoma (mRCC) and typically include papillary, chromophobe and collecting duct histologies. Despite differences in clinical behavior between subtypes they are often grouped as one due to small patient numbers. Hence, there is a lack of knowledge on type-specific prognosis and treatment options. Methods: Patients diagnosed with metastatic nncRRC (56 out of 526 patients; 10.8%) during the years 2005-2013 were retrospectively identified using data from medical records at two large academic centers in Sweden. The characteristics and outcome of those with papillary subtype (n = 44; 79% of nccRCC) was analyzed. Results: Metastatic papillary RCC patients were more often male (82%), had a median age of 69 years and 48% had M1 disease. 9% were type I, 41% type II, 4% mixed and 41% papillary NOS. 89% had a nephrectomy and 56% received at least one line of systemic therapy. The median overall survival (OS) of all papillary patients was 10.1 months. Factors associated with OS included performance status (PS; OS 25.8 months for ECOG PS 0-1 patients vs OS 3.1 months for ECOG PS > 1 patients, p = 0.00002), and systemic therapy (OS 23.4 months vs 3.8 months for patients not treated systemically, p = 0.002). Systemic therapies (ST) included VEGF targeting agents (88%), mTOR inhibitors (50%), or interferon (21%) for all lines. The most common first line ST was VEGF targeting agents (75%). 42% received one line, 33% two lines, and 25% three or more lines of ST. Characteristics of patients treated with ST included lower age at diagnosis, higher proportion of M1 disease and better PS. The reasons for not giving systemic treatment were primarily poor performance status or comorbidities. ECOG PS > 1 (p = 0.04) and poor MSKCC risk group (p = 0.02) were predictive of OS among patients treated with ST. Conclusions: Patients with metastatic papillary RCC and good performance status (ECOG PS 0-1) seem to benefit from systemic therapy using drugs primarily evaluated for clear cell RCC. However, patients not eligible for systemic therapy due to poor performance status or other reasons have a dismal prognosis.