The effect of time on racial differences in epithelial ovarian cancer (OVCA) diagnosis stage, overall and by histologic subtypes: a study of the National Cancer Database

Previous studies assessing racial and ethnic differences in ovarian cancer (OVCA) diagnosis stage fail to present subtype-specific results and provide historic data on cases diagnosed between 10 and 20 years ago. The purpose of this analysis is to assess non-Hispanic Black (NHB) and non-Hispanic White (NHW) differences in late-stage diagnosis including; (1) factors associated with late-stage diagnosis of invasive epithelial OVCA overall and by histologic subtypes, (2) potential changes across time and (3) current patterns of trends in a national cancer registry in the USA and Puerto Rico between 1998 and 2011. NHB and NHW OVCA cases were derived from the National Cancer Database (NCDB). Diagnosis stage was analyzed as a dichotomous and a four level-category variable, respectively; early (stages I and II; localized) versus late (stages III and IV; regional and distant) and stages I, II, III and IV. Diagnosis period was trichotomized (1998-2002, 2003-2007, 2008-2011). Racial differences in stage were tested using Chi-square statistics. Odds ratios (OR) and 95 % confidence intervals (95 % CI) were estimated using multivariable binomial and generalized ordered logistic regressions. Interactions between race and diagnosis period were evaluated. Between 1998 and 2011, 11,562 (7.8 %) NHB and 137,106 (92.2 %) NHW were diagnosed with OVCA. In adjusted models, NHB were significantly more likely diagnosed with late-stage OVCA than NHW (ORadj 1.26, 95 % CI 1.19-1.33). Interaction between race and diagnosis period was marginally significant (p (value) = 0.09), with racial differences in stage decreasing over time (1998-2002: ORadj 1.36, 95 % CI 1.23-1.49; 2003-2007: ORadj 1.27, 95 % CI 1.15-1.39; 2008-2011; ORadj 1.15, 95 % CI 1.05-1.27). NHB were also more likely to be diagnosed with stage 4 high-grade serous (ORadj 1.46, 95 % CI 1.22-1.74), clear cell (ORadj 2.71, 95 % CI 1.94-3.79) and mucinous (ORadj 2.78, 95 % CI 2.24-3.46) carcinomas than NHW. Racial differences in late-stage OVCA diagnosis exist; however, these differences are decreasing with time. Within NCDB, NHB are significantly more likely diagnosed with late-stage OVCA and more specifically high-grade serous, clear cell and mucinous carcinomas than NHW.