Late start and insufficient S-1 dose in adjuvant chemotherapy can lead to poor prognosis in stage II/III gastric cancer

Background

How the interval between surgery and S-1 adjuvant chemotherapy (ACT), and S-1 relative dose intensity (RDI) affect prognosis in patients with stage II/III gastric cancer who undergo gastrectomy with D2 lymph node dissection followed by S-1 ACT is unclear.

Methods

We enrolled 95 patients with histopathologically confirmed gastric adenocarcinoma treated with gastrectomy with D2 dissection, followed by S-1 ACT.

Results

Per ROC analysis, we used 32 days as the optimal cut-off interval to divide patients into the delayed group (started ACT ≥ 32 days) and the non-delayed group ( < 32 days). Their 5-year overall survival (OS) rates differed significantly (delayed: 54.2%, non-delayed: 85.4%; P < 0.0001). Per ROC analysis of patients without recurrence within 1 year post-surgery, patients were divided into the high RDI (RDI^High; ≥ 64.6%) and low RDI (RDI^Low; < 64.6%) groups. Their 5-year OS rates differed significantly (RDI^High: 76.9%, RDI^Low: 63.7%; P = 0.012). In multivariate analysis, RDI and interval before starting ACT were independent prognostic indicators. Five- year OS rates by subgroups were RDI^High/non-delayed: 84.0%, RDI^High/delayed: 66.8%, RDI^Low/non-delayed: 100%, and RDI^Low/delayed: 48.2% (P  < 0.0001).

Conclusions

Early initiation and sufficient RDI for S-1 ACT can improve the prognosis of patients with stage II/III gastric cancer.