Adjuvant Chemotherapy vs. Surgery Alone for pT3N0M0 Gastric Cancer

Background As both the role and clinical application of adjuvant chemotherapy (CTx) for pT3N0M0 gastric cancer after curative gastrectomy have fluctuated chronologically, the oncological benefit of adjuvant CTx in patients should be elucidated. Methods Between 2000 and 2018, 1083 patients underwent radical gastrectomy for pT3N0M0 gastric cancer and were subsequently divided into two groups: the surgery-alone group (n = 471) and the adjuvant CTx group (n = 612). Chronological changes in adjuvant CTx and various chemotherapeutic regimens were evaluated and disease-free survival was compared between the two groups. Risk factors for tumor recurrence were also analyzed. Results The proportion of patients in the surgery-alone group was more than 60% until 2001, whereas in the CTx group this increased to over 80%, especially after publication of the American Joint Committee on Cancer (AJCC) 7th edition staging manual. The main chemotherapeutic agents were tegafur-uracil (UFT) and 5-fluorouracil with leucovorin until 2008, whereas tegafur/gimeracil/oteracil (TS-1) has been the main agent since 2009. The 5-year disease-free survival was 89.2% in the surgery-alone group and 89.9% in the CTx group, which was not significantly different (p = 0.694). In multivariate analysis, larger tumor size (>= 4.5 cm) and venous invasion were significant risk factors for tumor recurrence. In addition, adjuvant CTx did not improve the oncological outcome, even in the large tumor size group (p = 0.760) and the venous invasion group (p = 0.753). Conclusions As adjuvant CTx did not show any oncological benefit in pT3N0M0 gastric cancer in this large-scale study, it might be unnecessary for these patients after curative gastrectomy.