Prognostic effect of excessive chemotherapy cycles for stage II and III gastric cancer patients after D2 + gastrectomy

BACKGROUND: According to relevant investigation and analysis, there are few research studies on the effect of excessive chemotherapy cycles after D2 gastrectomy on the survival of patients with gastric cancer. AIM: To determine whether excessive chemotherapy cycles provide extra survival benefits, reduce recurrence rate, and improve survival rate in patients with stage II or III gastric cancer. METHODS: We analyzed and summarized 412 patients with stage II gastric cancer and 902 patients with stage III gastric cancer who received D2 gastrectomy plus adjuvant chemotherapy or neoadjuvant chemotherapy. Analysis and comparison at a ratio of 1:1 is aimed at reducing realistic baseline differences (n = 97 in each group of stage II, n = 242 in each group of stage III). Progression-free survival, overall survival and recurrence were the main outcome indicators. RESULTS: When the propensity score was matched, the baseline features of stage II and III gastric cancer patients were similar between the two groups. After a series of investigations, Kaplan-Meier found that the progression-free survival and overall survival of stage II and III gastric cancer patients were consistent between the two groups. The local metastasis rate (P = 0.002), total recurrence rate (P < 0.001) and distant metastasis rate (P = 0.001) in the ≥ 9 cycle group of stage III gastric cancer were statistically lower than those in the < 9 cycle group. The interaction analysis by Cox proportional hazard regression model showed that intestinal type, proximal gastrectomy, and ≥ 6 cm maximum diameter of tumor had a higher risk of total mortality in the < 9 cycles group. CONCLUSION: Overall, ≥ 9 chemotherapy cycles is not recommended for patients with stage II and stage III gastric cancer because it has an insignificant role in the prognosis of gastric cancer. However, for patients with stage III gastric cancer, ≥ 9 cycles of chemotherapy was shown to significantly decrease recurrence.