CLINICAL T2 GASTRIC CANCER- IS THERE A SUPERIOR TREATMENT REGIMEN? AN EVALUATION OF NCCN PROPOSED TREATMENT OPTIONS
Rebecca Marcus1, Jennifer Keller*1, Sean Nassoiy1, Wade Christopher1, Douglas Hanes2, Melanie Goldfarb1
1John Wayne Cancer Institute, Santa Monica, CA; 2Providence Health and Services, Renton, WA
INTRODUCTION: Current NCCN guidelines afford clinicians multiple treatment options for clinical T2 (cT2) gastric cancer. These include isolated surgical resection (UFS), surgery combined with adjuvant chemotherapy (AT), and preoperative chemoradiation (NAT) followed by surgery. Since there is no evidence-based consensus regarding the optimal treatment strategy, the decision to recommend one regimen over another is based upon provider preferences and patient-specific factors. As such, we sought to evaluate usage of these treatment strategies and oncologic outcomes for patients with cT2 gastric adenocarcinoma.
METHODS: Patients ?18 years with cT2 gastric adenocarcinoma undergoing surgical resection between 2004-2017 were identified in the NCDB. After grouping patients by treatment regimen, we evaluated predictors of treatment utilization as well as oncologic outcomes between groups. Subgroup survival analyses were performed for both cT2N0 and pathologic (p) T2N0 patients.
RESULTS: Of 4,937 patients with cT2 gastric adenocarcinoma, 93.1% were cN0-N1; 41.5% of patients received NAT and 22.0% AT. Use of NAT increased from 2004-2017 (p<0.001), whereas UFS decreased (p<0.001), and there was no clear trend in the use of AT. After controlling for confounders, patients were more likely to receive NAT if they were diagnosed later in the study period (2004-2011 vs 2011-2017: OR 3.36, 95% CI 2.91-3.89) or had higher clinical N stage (cN1 vs cN0: OR 3.04, 95%CI 2.61-3.55; cN2 vs cN0: OR 2.75, 95%CI 2.09-3.61).
The 1,3,5-yr OS for the entire patient cohort were 84.9%, 59.9%, and 48.7%, respectively. In this cohort, patients receiving AT had improved OS as compared to other treatment regimens (UFS vs AT: aHR 1.44, 95% CI 1.10-1.87; NAT vs AT: aHR 1.57 95% CI 1.24-2.00). However, in subgroup analyses of both cT2N0 and pT2N0 patients, the beneficial effect of AT was no longer significant, nor was there a benefit to NAT. Interestingly, amongst the cT2N0 patients treated with UFS, 56.3% of patients were up-staged on final pathology based on T or N status. Amongst pT2N0 patients, those that received NAT had a decreased OS (aHR:1.30, 95% CI 1.02-1.64).
CONCLUSION: Although utilization of systemic therapy in the treatment of cT2 gastric cancer has increased, this has not translated into improved patient survival. This may be due to inaccuracies in clinical staging, and prospective studies evaluating optimal staging techniques for gastric adenocarcinoma are needed. Moreover, pathologic results after use of NAT may offer clinicians an indication of tumor biology with prognostic value. Ongoing and future analyses of newer therapeutic regimens currently in use for gastric cancer may ultimately reveal further prognostic value or survival differences amongst potential treatment regimens.
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