Evolving trends in non-clear cell renal cell cancer (RCC) epidemiology: A large registry analysis of 4,483 patients.

Abstract

4607 Background: Non-clear cell (ncc) RCC is uncommon but includes a heterogeneous group of histologic subtypes such as papillary, chromophobe (Chr), medullary (Med), and collecting duct (CD) cancers. We used a large cancer registry to define nccRCC clinical features and outcomes, identify prognostic variables, and to generate hypotheses for further study. Methods: Invasive RCC tumors in the California Cancer Registry from 1998-2009 among adults > 18 years of age (n=38,251) were analyzed. Baseline clinical and tumor variables were collected. Primary outcome measures were 3-year cause-specific (CSS) and overall survival (OS). Uni- and multivariate survival analysis were used to identify predictors of CSS and OS. Results: Of 38,251 RCC cases, 19,149 (50%) were of clear cell type; 14,619 (38.2%) were “unclassified.” Thus, 4,483 (11.7%) nccRCC cases were identified and included in this analysis. Of these, 3,304 (73.7%) were diagnosed in 2004-09, suggesting a shift to more precise coding of histologic subtypes starting in the early 2000s. Histology distribution (n, %): papillary - 2,863 (63.9%); Chr - 1,507 (33.6%); and other including Med and CD - 113 (2.5%). Variables associated with significantly better OS and CSS (univariate analysis) were Chr histology, female sex, and higher socioeconomic status (SES). Significantly worse OS and CSS were seen in Med+CD, age > 65 yrs, no nephrectomy (Nx), and higher stage. Non-hispanic blacks had significantly worse OS and CSS, while the “targeted therapy era” (2004-2009) was associated with better OS. Multivariate analysis showed the following to be independently associated with outcomes (all p <0.001; Hazard Ratios [HR] shown for CSS and OS): Chr histology (0.48, 0.56), Med+CD histology (2.99, 2.42), no Nx (2.84, 3.18), regional stage (5.84, 1.98), distant stage (25.7, 7.67); and non-hispanic blacks (1.5,2 p=0.006; 1.25, p=0.03). Age > 65 yrs (HR 1.78, p<0.001) and high SES (HR 0.88, p=0.001) were associated with OS but not CSS. Conclusions: This is among the largest registry analyses of nccRCC ever performed, showing emerging trends in this uncommon RCC subset. Clinical variables associated with CSS and OS were identified that can inform the design of future clinical trials in nccRCC.