Advantages of adjuvant chemotherapy using S-1 following minimally invasive gastrectomy for gastric cancer versus open surgery: a propensity score-matched analysis.

[BACKGROUND] It is essential to ensure optimal adherence to adjuvant chemotherapy regimens following gastric cancer surgery. However, treatment intensity for S-1 as adjuvant chemotherapy has not as yet been compared between minimally invasive (MI) and open (Open) surgery.

[METHODS] We retrospectively compared dose modification of adjuvant S-1 between MI and Open surgery in patients undergoing R0 gastrectomy for gastric or esophago-gastric junction cancer at the Cancer Institute Hospital Tokyo, Japan, during the period from 2012 to 2022, and receiving S-1 for pStage II or S-1 plus docetaxel for pStage III as adjuvant chemotherapy. Propensity score matching (PSM) was conducted to adjust for possible confounders.

[RESULTS] In total, 323 patients were initially included. After PSM, 158 patients remained, 79 in each group. The adjuvant chemotherapy completion rates were similar in the two groups. However, the proportion of patients who required S-1 dose reduction was significantly lower in the MI than in the Open group (43.0% vs. 65.8%, p = 0.004). In addition, the MI group had significantly fewer patients requiring suspension of S-1 than the Open group (46.8% vs. 64.6%, p = 0.025). Moreover, the frequency of adverse events of grade ≥ 3 was significantly lower in the MI than in the Open group (17.7% vs. 31.7%, p = 0.042).

[CONCLUSIONS] In adjuvant chemotherapy for gastric cancer, minimally invasive surgery may offer better treatment intensity for oral S-1 administration than open surgery.