"Endometrial cancer is the most commonly diagnosed gynecologic cancer in the United States and incidence rates have been rising for many years," said Michele Cote, Ph.D., associate professor of Oncology for WSU and the Barbara Ann Karmanos Cancer Institute. "We set out to investigate whether the increasing incidence and mortality from endometrial cancer are equally distributed by race/ethnicity and endometrial cancer subtype.

"The most significant finding was that non-Hispanic black women had poorer outcomes compared with non-Hispanic white women diagnosed with the same subtype of endometrial cancer and at the same stage of disease, while Hispanic and Asian women had similar or better outcomes compared with their non-Hispanic white counterparts," Dr. Cote said. "Earlier studies have suggested that disparities in outcomes from endometrial cancer might be explained by differences in tumor subtype or stage at diagnosis, but our data suggest that disparities persist even when these factors are controlled for."

Dr. Cote and colleagues analyzed endometrial cancer incidence and mortality data from the Surveillance, Epidemiology, End Results database, including only the 120,513 cases diagnosed from 2000 to 2011.

During the 12 years studied, endometrial cancer rates increased among all racial and ethnic groups, with rates increasing fastest, at 2.5 percent per year, among non-Hispanic black women and Asian women. Non-Hispanic black women had higher rates of all the aggressive endometrial cancer subtypes than non-Hispanic white, Asian and Hispanic women.

Mortality rates for the aggressive endometrial cancer subtypes were more than one and one-half times higher among non-Hispanic black women compared with non-Hispanic white women, while mortality rates for these subtypes were similar or lower among Asian and Hispanic women compared with non-Hispanic white women.

Analysis of overall five-year survival rates showed that non-Hispanic black women had poorer survival rates at every stage of diagnosis, regardless of endometrial cancer subtype, compared with non-Hispanic white women. Five-year survival rates were similar or higher among Asian and Hispanic women compared with non-Hispanic white women.

"It was somewhat surprising that the endometrial cancer survival disparity we identified was limited to non-Hispanic black women, because many of the challenges previously linked to worse outcomes, including low socioeconomic status and high rates of obesity and diabetes, are also experienced by Hispanic women, but that population did not have poor outcomes," Dr. Cote said. "We are, therefore, interested in investigating whether there are molecular differences in endometrial tumors of the same subtype from women of different races or ethnicities diagnosed at the same stage of disease."

Dr. Cote said a limitation of the study is that the data analyzed were from the SEER database, which meant researchers did not have tumor samples and were unable to perform a review of the tumor subtype to ensure they had been classified correctly. In addition, SEER does not collect information on other factors that may be associated with incidence and survival, thus potential causes for the disparities identified in this study cannot be further examined.

The study was funded, in part, by the Epidemiology Core and NIH Center Grant P30CA022453.