Despite researchers compiling data from an equal-access system and adjusting for age, diagnosis period, tumor stage, tumor histology/grade, and whether the patient had adjuvant treatment, the overall survival disparity between Black and White women with endometrial cancer persisted.
While looking at data from an equal-access healthcare system, researchers saw continuing racial disparities for overall survival (OS) outcomes between Black women with endometrial cancer (EC) and White women with EC suggesting that factors other than access to care are driving this disparity, according to research from Gynecologic Oncology.1
Previous studies have shown that the mortality rate for Black women with EC is double that of White women with WC, even though the overall incidence rate is lower among Black women. These studies have also shown that unequal access to care is a factor in these disparities, however, researchers wanted to see what the survival outcomes looked like in an equal-access health care system. Therefore, they used data from the Military Health System (MHS), which provides equal care to its beneficiaries regardless of their racial or ethnic background.
Researchers found, however, that despite compiling data from an equal-access system and adjusting for age, diagnosis period, tumor stage, tumor histology/grade, and whether the patient had adjuvant treatment, the OS disparity between Black and White women with EC persisted (HR, 1.64; 95% CI, 1.19-2.27). Moreover, a multivariable analysis stratified by tumor features and treatment showed that the racial disparity was only among those Black and White patients with low-risk features, defined as stage I/II disease or low-grade EC, or those with no adjuvant treatment.
“While it is not clear why the racial differences in survival were not shown in high-risk tumors assuming more aggressive tumors feature sin Black patients, it might result from complex effects of multiple factors, such as tumor-risk related molecular features, utilization of medical care, and family support,” the researchers wrote when explaining the differences between patients with high-risk and low-risk EC. “One of the factors might be no or minimal financial barriers to and thus wide utilization of adjuvant treatment, which is more widely used for high-grade and late-stage tumors, in the MHS that provides universal care. As a result, racial differences in survival might be mitigated among patients with high-grade or late-stage disease or who received adjuvant treatment.”
Using data from the US Department of Defense’s Automated Central Tumor Registry, the researchers categorized women with EC as either non-Hispanic White (NHW) or non-Hispanic Black (NHB). The study included 144 NHB patients and 1,439 NHW with EC diagnosed between the years 1988 and 2013 with most of the disease diagnosed at stage I, 95 vs 1101 patients, respectively. Moreover, low grade endometrioid cancers made up the majority in both groups with 76.7% (n = 1104) in the NHW group and 54.2% (n = 78) in the NHB group.
In the stage I/II group the difference in OS was significant between the two groups with a HR of 1.81 (95% CI, 1.2-2.8, P = .0076). In patients with low grade endometrioid cancer the HR was 2.47 (95% CI, 1.6-3.9, P = .00002), whereas the ungraded endometroid group had a 1.03 HR (95% CI, .12-8.6, P = .9788). Those patients with no adjuvant treatment had a HR of 2.15 (95% CI, 1.31-3.53, P = .0026) compared to an HR of 1.14 (95% CI, 0.12-10.1, P = .9098) in patients that could not be confirmed if they had adjuvant treatment. These disparities also persisted throughout each diagnosis period that the researchers split data in with 1988-1994 at a HR of 1.04 (95% CI, .41-2.62, P = .9331), 1995-2004 with a HR of 1.68 (95% CI, 1.07-2.65, P = .0241), and 2005-2013 at 1.41 (95% CI, .75-2.68, P = .2899).
“Several factors might explain a poorer survival among Black women than White women when access to care is equal. First, histologic subtype may vary among racial/ethnic groups,” explained the researchers. “Previous studies have reported that Black women were more likely to present with non-endometroid histologic subtypes including serous and clear cell carcinoma, which are more aggressive and have higher risks of recurrence, progression, and mortality. This was also observed in our study, although the numbers of women with these types were too small (data not shown).”2
1. Park AB, Darcy KM, Tian C, et al. Racial disparities in survival among women with endometrial cancer in an equal access system. Gynecol Oncol. 2021;163(1):125-129. doi: 10.1016/j.ygyno.2021.07.022
2. Smotkin D, Nevadunsky NS, Harris K, Einstein MH, Yu Y, Goldberg GL. Histopathologic differences account for racial disparity in uterine cancer survival. Gynecol Oncol. 2012;127(3):616-9. doi: 10.1016/j.ygyno.2012.08.025