ABSTRACT
Objective: To investigate the safety and efficacy of oxaliplatin combined with S-1 (SOX) as adjuvant chemotherapy after D2 radical gastrectomy for locally advanced gastric cancer. Methods: A descriptive case series study was applied. Case inclusion criteria: (1) locally advanced gastric cancer confirmed by endoscopic biopsy or surgical specimen pathology as gastric adenocarcinoma; (2) receiving D2 radical gastric resection followed by SOX regimen adjuvant chemotherapy. Case exclusion criteria: (1) postoperative pathological TNM stage I or IV; (2) acute complications and emergency surgeries; (3) receiving neoadjuvant therapy; (4) concurrent malignancies and complications compromising patients' treatment or survival; (5) without receiving adjuvant SOX chemotherapy. A total of 94 patients with stage II-III gastric cancer who underwent D2 radical gastrectomy and postoperative adjuvant SOX chemotherapy at department of Gastrointestinal Surgery, Peking University People's Hospital from January 2014 to December 2019 were retrospectively enrolled. Chemotherapy-related adverse events, overall survival (OS) and progression-free survival (PFS) were analyzed. Kaplan-Meier survival analysis was performed and log rank test was used to analyze the difference between groups. P<0.2 or clinically significant indicators in univariate analysis were included in Cox regression model for multivariate survival analysis. Results: Among these 94 patients, there were 65 males and 29 females with an average age of (58.2±12.1) years; 33 patients with hypertension, diabetes mellitus, or cardiovascular and cerebrovascular diseases, 11 patients with family history of gastrointestinal tumors; 59 patients with tumors locating in the antrum or pylorus, 16 patients in the gastric body, 19 patients in the gastric fundus or cardia; 29 patients underwent total gastrectomy, 5 patients underwent proximal subtotal gastrectomy, and 60 patients underwent distal subtotal gastrectomy. In this study, 73 patients (77.7%) completed at least 5 cycles of adjuvant SOX regimen chemotherapy. Grade 3-4 adverse reactions included thrombocytopenia (23.4%, 22/94), nausea and vomiting (18.1%, 17/94) and peripheral neurotoxicity (6.4%, 6/94). Eighty-nine patients (94.7%) completed follow-up with a median follow-up time of 32 months. The 3-year and 5-year OS rates were 89.8% and 83.7%, respectively, and the 3-year and 5-year PFS rates were 81.4% and 78.1%, respectively. Taking 5 chemotherapy cycles as the cut-off point, the 3-year OS rate and 3-year PFS rate were 72.2% and 53.9% in the adjuvant chemotherapy < 5 cycles group, and 93.7% and 87.1% in the adjuvant chemotherapy ≥5 cycles group, respectively; the differences were statistically significant (P=0.029, P=0.006). Univariate analysis showed that the adjuvant chemotherapy < 5 cycles group was associated with worse 3-year OS (P=0.029). Multivariate analysis showed that insufficient chemotherapy cycle (HR=9.419, 95% CI: 2.330-38.007, P=0.002) was an independent risk factor for 3-year OS. Meanwhile, univariate analysis showed that the adjuvant chemotherapy <5 cycles (P=0.006), preoperative CEA > 4.70 μg/L (P=0.035) and adjacent organ resection (P=0.024) were associated with worse 3-year PFS. Multivariate analysis showed that adjuvant chemotherapy <5 cycles (HR=10.493, 95% CI: 2.466-44.655, P=0.001) and adjacent organ resection (HR=127.518, 95% CI: 8.885-1 830.136, P<0.001) were independent risk factors for 3-year PFS. Conclusions: Oxaliplatin combined with S-1 as an adjuvant chemotherapy regimen for locally advanced gastric cancer has high efficacy and low incidence of adverse reactions. At least 5 cycles of SOX regimen adjuvant chemotherapy can significantly improve prognosis of patients with stage II-III gastric cancer.