Chemotherapy Versus Chemotherapy Plus Chemoradiation as Preoperative Therapy for Resectable Gastric Adenocarcinoma: A Propensity Score-Matched Analysis of a Large, Single-Institution Experience

Background We compared oncologic outcomes of patients who received neoadjuvant chemotherapy (CT) with those of patients who received neoadjuvant chemotherapy plus chemoradiation (CRT) for resectable gastric adenocarcinoma. Methods We compared oncologic and survival outcomes of patients who received CT or CRT for gastric adenocarcinoma at our institution between July 1995 and July 2018. We analyzed propensity score-matched cohorts based on age, sex, race, tumor histologic characteristics, and clinical stage. Results We identified 440 patients (mean age 61 +/- 12 years, 62% male, 55% white); 345 (78%) received CRT, and 95 (22%) received CT. The propensity score-matched cohorts included 65 patients who received CT and 65 who received CRT. The CRT group had similar frequencies of R1 resection margins to the CT group (7.7% vs. 6.2%,p = 0.75) but significantly higher frequency of pathologic complete response (27.7% vs. 1.5%,p < 0.001). The CRT group had lower pathologic stages (p = 0.002). Median disease-free survival was 50.9 months (95% confidence interval [CI]: 4.7-97.2) in the CT group and 122.1 months (95% CI: 69.0-175.1) in the CRT group (p = 0.07). Median overall survival was 70.7 months (95% CI: 23.9-117.5) in the CT group and 122.1 months (95% CI: 68.7-175.4) in the CRT group (p = 0.21). Conclusions Compared with CT, CRT for resectable gastric adenocarcinoma is associated with higher rates of pathologic complete response and subsequent lower final pathologic stage, but survival differences are not significant. Ongoing investigation is necessary to better determine the optimal neoadjuvant therapy and identify patients who receive optimal benefit from CRT.