Impact of hospital volume on racial disparities and outcomes for endometrial cancer.

OBJECTIVE: Little is known about the influence of hospital procedural volume on racial disparities for uterine cancer. We examined whether the magnitude of the survival differential between black and white women varied based on hospital procedural volume for endometrial cancer.

METHODS: We utilized the National Cancer Data Base to examine women with endometrial cancer from 1998 to 2012. Annualized hospital procedural volume was calculated and hospitals grouped into volume-based quartiles. Multivariable models were developed to examine differences in two and five-year survival between black and white women across the hospital volume categories. Patients were classified as early or advanced stage and as type I (low grade, endometrioid) or type II (high grade endometrioid, other histologies) cancers.

RESULTS: We identified 243,422 (75.0%) white and 27,764 (8.6%) black women treated at 1059 hospitals. Regardless of hospital volume, black women had decreased survival. For each tumor class, the absolute difference in adjusted two-year survival between black and white women decreased with increasing hospital volume. For example, for women with early-stage, type I tumors, the adjusted two-year survival differential between blacks and whites was -1.4% (95%CI, -2.4 to -0.5%) at low volume centers and decreased to -0.5% (95%CI, -0.9 to 0%) at high-volume hospitals (P<0.0001). For advanced stage, type I tumors, the adjusted survival differential decreased from -12.4% (95%CI, -24.0 to -0.9%) to 1.2% (95%CI, -2.9 to 5.3%) at high volume hospitals (P<0.0001).

CONCLUSION: Black race is an independent predictor of mortality. The impact of race on mortality is mitigated, albeit not eliminated, by increasing hospital volume.