Background: Anthropometric and hormone-related factors are established endometrial cancer risk factors; however, little is known about the impact of these factors on endometrial cancer risk in non-White women.
Methods: Among 110,712 women participating in the Multiethnic Cohort (MEC) Study, 1150 incident invasive endometrial cancers were diagnosed. Hazard ratios (HRs) and 95% confidence intervals (CIs) for associations with endometrial cancer risk for race/ethnicity and for risk factors across racial/ethnic groups were calculated.
Results: Having a higher body mass index (BMI) at baseline or age 21 years was strongly associated with increased risk (pint race/ethnicity ≥ 0.36). Parity (vs nulliparity) was inversely associated with risk in all the groups except African Americans (pint 0.006). Current use of postmenopausal hormones at baseline (PMH-E; vs never use) was associated with increased risk in Whites and Japanese Americans (pint 0.002). Relative to Whites, endometrial cancer risk was lower in Japanese Americans and Latinas and non-significantly higher in Native Hawaiians. Risk in African Americans did not differ from that in Whites.
Conclusions: Racial/ethnic differences in endometrial cancer risk were not fully explained by anthropometric or hormone-related risk factors. Further studies are needed to identify reasons for the observed racial/ethnic differences in endometrial cancer risk.