LACK OF NATIONAL ADOPTION OF EVIDENCE-BASED TREATMENT FOR RESECTABLE GASTRIC ADENOCARCINOMA
Tiffany C. Lee*, Koffi Wima, Mackenzie C. Morris, Michael E. Johnston, Jeffrey Sussman, Shimul A. Shah, Syed Ahmad, Sameer Patel, Gregory C. Wilson
University of Cincinnati, Cincinnati, OH
Introduction: Level 1 evidence for multimodal therapy for the treatment of resectable gastric adenocarcinoma from the Intergroup 0116 (2001) and MAGIC (2006) trials have demonstrated survival benefit of adjuvant chemoradiation (CRT) and perioperative chemotherapy, respectively. There are limited data evaluating changes in treatment patterns since publication of the MAGIC trial. In this current study, we evaluated the adoption of evidence-based treatment in the post-MAGIC era and the impact of implementing evidence-based treatment on survival.
Methods: 7,058 patients with resectable gastric adenocarcinoma undergoing definitive surgical resection between 2004-2015 were analyzed using the NCDB. Patients with gastroesophageal junction tumors were excluded. Patients were categorized by disease stage and treatment regimens. Kaplan-Meier (KM) survival analyses and multivariate Cox regression survival analyses were performed.
Results: Evidence-based treatment (perioperative chemotherapy or adjuvant CRT) increased from 21.0% in 2004 to 37.7% in 2015. Within this cohort, utilization of perioperative chemotherapy increased over time, surpassing adjuvant CRT in 2011 (Figure 1). Both evidence-based treatment and neoadjuvant CRT had better overall survival (OS) than other treatments for clinical stage II-III patients (p<0.05). OS for clinical stage I-III was higher from 2010-2015 compared to 2004-2009 (p<0.05). On multivariate analysis, neoadjuvant CRT (HR 1.41) and other treatments (HR 1.21) were associated with worse OS compared to evidence-based treatment (p<0.05). Other factors associated with worse OS (p<0.05) included: <15 lymph nodes examined (HR 1.39), positive lymph nodes (HR 1.33), positive margin status (HR 1.41 for R1, 2.69 for R2), and total (HR 1.16) vs. partial gastrectomy.
For clinical stage III patients (n=2,402), only 806 (33.6%) received evidence-based treatment, while 487 (22.2%) underwent surgery alone. In this cohort, perioperative chemotherapy was associated with higher OS compared to adjuvant CRT (Figure 2). On multivariate analysis, both perioperative chemotherapy (HR 0.49) and adjuvant CRT (HR 0.31) were associated with better OS than surgery alone (p<0.05). Notably, only 360/1262 (28.5%) patients in the perioperative chemotherapy group completed their postoperative therapy, and completion of postoperative chemotherapy was associated with improved OS (p<0.05).
Conclusions: In the decade since publication of the MAGIC trial, utilization of evidence-based treatment regimens for resectable gastric adenocarcinoma has continued to increase, with perioperative chemotherapy surpassing adjuvant CRT as the preferred practice. However, overall utilization of these regimens remains quite low despite association with improved OS. Further investigation is needed to understand reasons behind continued use of non-evidence-based treatment regimens.
Figure 1. Percentage of patients receiving evidence-based treatment regimens over time.
Figure 2. Kaplan-Meier survival analysis for clinical stage III patients comparing perioperative chemotherapy versus adjuvant chemoradiation treatment regimens.
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