Evolving epidemiologic trends in nonclear cell renal cell cancer: an analysis of the California Cancer Registry.

OBJECTIVE: To evaluate the California Cancer Registry in order to define nonclear cell renal cell cancer (RCC) clinical features and outcomes, identify prognostic variables, and generate hypotheses for further study.

METHODS: Patients with invasive RCC tumors in the California Cancer Registry from 1998 to 2009 (n = 38,251) were analyzed, of which 4483 (11.7%) were of the nonclear cell type. Baseline clinical demographics and tumor characteristics were collected. Primary outcome measures were 3-year cause-specific survival (CSS) and overall survival (OS).

RESULTS: Of 4483 nonclear cell RCC cases, 3304 (73.7%) were diagnosed between 2004 and 2009. Histologic distribution was as follows: papillary 63.9%, chromophobe 33.6%, and "other" 2.5% (including medullary and collecting duct tumors). Univariate analysis showed that chromophobe histology, female sex, and higher socioeconomic status were associated with significantly better OS and CSS. Patients in the later era (2004-2009) appeared to have better OS. Multivariate analysis showed the following to be independently associated with outcomes (hazard ratios shown for CSS and OS, respectively): chromophobe (0.48, 0.56; P <.001), medullary/collecting duct (2.99, 2.42; P <.001), no nephrectomy (2.84, 3.18; P <.001), regional stage (5.84, 1.98; P <.001), distant stage (25.7, 7.67; P <.001), and non-Hispanic blacks (1.5, P = .006; 1.25, P = .03).

CONCLUSION: This large registry analysis demonstrated emerging epidemiologic trends in this uncommon RCC subset. Clinical variables associated with CSS and OS were identified that can potentially inform the design of future clinical trials in nonclear cell RCC.