N. Ikoma1,2, J. Cormier1, B. Feig1, X. L. Du2, J. Yamal2, P. Das1, J. A. Ajani1, C. Roland1, K. Fournier1, R. Royal1, P. Mansfield1, B. Badgwell1 1University Of Texas MD Anderson Cancer Center,Houston, TEXAS, USA 2University Of Texas Health Science Center At Houston,Houston, TEXAS, USA
Introduction:
Racial disparity is widely reported in gastric cancer in the United States. The use of preoperative chemotherapy in patients with resectable gastric cancer has sharply increased over the past 10 years; however, no studies have investigated whether race/ethnicity is associated with the use of preoperative chemotherapy or subsequent outcomes in gastric cancer.
Methods:
Patients with clinical T2-4bN0-1M0 gastric adenocarcinoma, as defined by the AJCC 8th edition, who underwent gastrectomy during 2006-2014 were identified from the National Cancer Database. The main exposure variable was race/ethnicity, and the main outcome variable was preoperative chemotherapy use, defined by systemic therapy surgery sequence code. Multiple logistic regression was conducted to examine factors associated with preoperative chemotherapy use. A multiple Cox regression model was used to examine overall survival, as a secondary analysis.
Results:
We identified 16,945 patients who met study criteria, of whom 8,286 (49%) underwent preoperative chemotherapy. The median age was 65 years (interquartile range 57-74 years), and 69% were male; 71% were non-Hispanic (NH) white, 12% were NH black, 9% were Hispanic, and 7% were Asian and Pacific Islander (API). The use of preoperative chemotherapy remarkably increased over the study period, from 34% in 2006 to 65% in 2014. Preoperative chemotherapy was more commonly used in cardia tumors than in non-cardia tumors (83% vs. 44%, in 2014). In multivariable analysis, NH blacks (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.67-0.86; p<0.001), Hispanics (OR 0.83, 95% CI 0.72-0.95; p=0.006), and APIs (OR 0.62, 95% CI 0.53-0.72; p<0.001) were associated with less frequent use of preoperative chemotherapy compared with NH whites. Increases in preoperative chemotherapy use over time were homogeneous between race/ethnicity groups. Insurance status, education level, and treatment at non-academic hospital mediated an enhanced effect of racial/ethnic disparity in preoperative chemotherapy use. In Cox regression models, use of preoperative chemotherapy and radiation therapy was associated with reduced racial/ethnic disparity in overall survival.
Conclusion:
Racial/ethnic disparity in the use of preoperative chemotherapy and outcomes exists among gastric cancer patients in the United States. Race was independently associated with low frequency of preoperative chemotherapy use, and no insurance status, low education level, and treatment at non-academic hospital mediated an enhanced effect of the disparity in preoperative chemotherapy. Efforts to improve the access to high-quality cancer care in minority groups may reduce racial disparity in gastric cancer in the United States.
