A. Hunt1, L. Zhang2, J.S. Hasler2, A.M. Villano3, A.S. Porpiglia3, E. Papai3, S.S. Reddy3, J.M. Farma3, S.H. Greco3 1Temple University, Lewis Katz School Of Medicine, Philadelpha, PA, USA 2Fox Chase Cancer Center, Biostatistics & Bioinformatics, Philadelphia, PA, USA 3Fox Chase Cancer Center, Surgical Oncology, Philadelphia, PA, USA
Introduction: The treatment of locally advanced gastric cancer has continued to change over the past several decades with the current standard consisting of perioperative chemotherapy. In other cancers, a complete pathologic response (pCR) in the primary tumor has been linked to improved outcomes and may affect adjuvant treatment. However, there is a lack of data on the current rates of pCR in gastric cancer and its association with specific clinical outcomes.
Methods: We retrospectively identified all gastric adenocarcinoma patients with clinical stage T2N0M0 or higher who received neoadjuvant chemotherapy without radiation using the National Cancer Database (2004-2021). Clinical and demographic parameters were collected and analyzed according to pCR status. To evaluate whether obtaining a pCR or completing adjuvant therapy after pCR improves overall survival (OS), we used Kaplan-Meier plots and conducted log-rank tests for comparison. Cox proportional hazards regression was employed to account for the effects of patient, tumor, and treatment factors. Additionally, a generalized estimating equations (GEE) model was used to identify clinical factors associated with pCR.
Results: 4253 patients met inclusion criteria. Of these, 341 patients had a pCR (8.0%). Factors associated with pCR included diagnosis before 2018 (p=0.002) and a higher clinical N stage of N1 or N2 (p=0.004, p=0.014). There was no association between pCR and facility type or location. Overall, rates of pCR increased from 2004-2017. pCR was associated with improved OS after adjusting with multivariable analysis (HR 0.36 [0.29,0.44], p=<0.0001) (Figure 1). In addition, in patients who achieved pCR after neoadjuvant therapy, there was no association with the completion of adjuvant therapy and improved overall survival (p=0.39).
Conclusion: Gastric cancer patients undergoing neoadjuvant chemotherapy prior to surgery who obtain a pCR have improved overall survival.