Abstract A84: Grade- and stage-specific age incidence patterns of serous ovarian epithelial cancer among different racial and ethnic groups in the United States

Molecular and epidemiologic studies suggest that low- and high-grade serous ovarian epithelial cancers (sOEC) have distinct etiological pathways. However little is known about patterns in tumor grade and stage among different racial and ethnic groups in the US.

Data on sOEC (ICD-O-3 codes 8441, 8460-1) were obtained from the Surveillance, Epidemiology, and End Results 17-registry database (SEER17) for non-Hispanic Whites (NHW), Hispanic Whites (HW), African Americans (AA), and Asian Pacific Islanders (API), ages 20-84 years, for the period 2000-2005. Tumor stage was based on the American Joint Committee on Cancer Classification (AJCC) 6th edition, and was categorized as early (Stage I-II) and late (Stage III-IV). Tumor grade was categorized as low (well or moderately differentiated) and high (poorly differentiated or undifferentiated). Overall age-adjusted and age-specific rates of sOEC were calculated and stratified by race/ethnicity, stage, and/or grade using Poisson regression. Likelihood ratio tests were used to assess age interactions; age-specific incidence rate curves were smoothed using regression splines.

There were a total of n=11,569 cases of sOEC; of which 79.8% were NHW, 9.2% HW, 5.4% AA, and 5.3% API. The age-adjusted rate for high-grade sOEC was nearly three times the rate for low-grade sOEC (IRR=2.85). Within low-grade sOEC, the IRR=2.62 for late- to early-stage; within high grade sOEC, the IRR=6.67 for late- to early-stage. Age-specific rates were similar for all groups except HW. There was significant age interaction with tumor grade (p<0.001 for both early and late stage), though within early-stage, the main effect of grade was non-significant (p=0.078). When age-specific rates were stratified by stage and grade, there was a highly significant age interaction in WH compared to WNH (reference group) in the late-stage/high-grade stratum (p=2.37x10-05).

Grade appears to play an important role in late-stage sOEC, particularly among WH. Though age incidence patterns by grade were generally similar among race/ethnicity groups in late-stage sOEC, the age incidence pattern for high-grade sOEC within late-stage was distinct for WH.

Citation Information: Cancer Prev Res 2008;1(7 Suppl):A84.