Characteristics and Outcomes of Tumors Arising From the Distal Nephron

Abstract

To compare the characteristics and predictors of cancer-specific survival (CSS) of 2 rare distal nephron tumors--medullary renal cell carcinoma (MRCC) and collecting duct carcinoma (CDC). All cases of histologically verified MRCC and CDC reported to The Surveillance, Epidemiology and End Results (SEER) database between 1995 and 2007 were considered. A number of characteristics were compared by tumor histology. Subset analyses were performed for metastatic patients and those managed surgically. CSS was analyzed using Cox proportional hazard models. Overall, 21 cases of MRCC and 227 cases of CDC met the criteria for analysis. Patients with MRCC were younger (median 24 vs 63 years, P < .001), more often black (71.4% vs 22.7%, P < .001), metastatic at presentation (71.4% vs 27.8%, P < .001), and less likely to undergo surgery (61.9% vs 85.6%, P = .015) compared with patients with CDC. Tumor size was similar between MRCC and CDC (median 6 vs 5 cm, P = .70). Median survival was 5 months for MRCC and 30 months for CDC (P < .001). In metastatic MRCC and CDC patients, surgery predicted CSS (HR 4.61 and 2.24, both P ≤.05) despite having larger primary tumors than those managed nonsurgically (median 7.5 vs 5.0 cm, P < .01). Patients with MRCC present younger, at a later stage, and are more often black than patients with CDC. The stage migration toward localized kidney cancer is not apparent for these tumors. Although both cancers have a poor prognosis, the clinical and survival characteristics are distinct. Patients selected for cytoreductive surgery have improved survival.