Background: Few studies have compared the survival advantage of complete pathologic response (cPR) achieved through neoadjuvant chemotherapy (nCT) versus neoadjuvant chemoradiotherapy (nCRT) in gastric adenocarcinoma. Our study utilizes a large national cancer database to address this question.
Patients and methods: This is a retrospective review of patients with clinical stage I to III gastric adenocarcinoma from 2004 to 2013 who received nCT or nCRT. Patients who achieved cPR were selected. Associations were evaluated using Mann-Whitney U and Fisher's exact tests. Survival information was summarized using standard Kaplan-Meier methods, where estimates of the median and 5-year survival rates were estimated with 95% confidence intervals.
Results: A total of 413 patients who had cPR were identified. Eighty-four patients received nCT and 329 patients received nCRT. Patients in the nCRT group had higher clinical stage (88.4% vs. 75.0%) and more proximal location of tumors (95.4% vs. 45.2%). The nCT group (n = 84) had a 94% 5-year survival rate, while the nCRT group's (n = 329) rate was 60% (p < 0.001). On Cox regression modeling using a propensity-weighted approach, nCT treatment was an independent predictor of improved overall survival (nCRT vs. nCT; HR 10.44, p < 0.001).
Conclusions: The use of nCT leads to a significant increase in overall survival in patients when compared with nCRT for those who achieved cPR in gastric adenocarcinoma. While this study is limited in identifying the cause for this difference in overall survival, this important finding nonetheless requires further investigation and should be considered in the development of future gastric cancer trials.