Duration of Adjuvant Chemotherapy for Gastric Cancer Patients at Pathological N3 Stage

Duration of Postoperative Adjuvant Chemotherapy (3-4 Months Versus 5-6 Months) for Gastric Cancer Patients at Pathological N3 Stage: a Retrospective Study

The goal of this retrospective study is to compare the efficacy and safety of 3-4 months to 5-6 months of CapOx/SOX adjuvant chemotherapy in pathological N3 gastric cancer patients.

Due to a heavy metastatic node burden, pathological stage N3 (pN3) gastric cancer (GC) patients have extremely poor prognoses. Except for surgical resection, postoperative adjuvant chemotherapy is the major treatment strategy to improve survival for these patients. Capecitabine plus oxaliplatin (CapOx) and S-1 plus oxaliplatin (SOX) were considered the effective treatment for stage II and III GC after D2 gastrectomy in the CLASSIC and RESOLVE trials. But N3b (positive lymph nodes ≥16) and T1-3N3 patients were omitted in these two trials, respectively. Moreover, only 66.5% of patients finished 6 months of chemotherapy in the CLASSIC trial, and in the RESOLVE trial, 17-19% of patients required dose reductions and about 19% of patients discontinued chemotherapy due to drug-related toxicity for 6 months of chemotherapy. Particularly, cumulative administration of oxaliplatin led to peripheral sensory neurotoxicity, which caused poor quality of life and treatment compliance. Recently, a prospective analysis of six randomized, phase 3 trials with 12834 participants (IDEA trail) for stage III colon cancer, demonstrated that 3 months of CapOx was as effective as 6 months with relatively lower recurrence risk, no significantly different overall survival, and fewer adverse effects. However, there were no relevant studies to explore the optimal duration of chemotherapy for pN3 GC patients.

This study aims to compare the efficacy and safety of 3-4 months to 5-6 months of CapOx/SOX adjuvant chemotherapy in pathological N3 gastric cancer patients.

Inclusion Criteria:

1. 18-80 years old
2. Pathological stage N3 GC (≥7 positive lymph nodes) after curative surgery according to the AJCC TNM staging system, 8th edition
3. Histologically confirmed R0 resection, defined as no macroscopic or microscopic residual tumor
4. Postoperative chemotherapy with CapOX or SOX doublet regimen, initiating within 6 weeks after curative gastrectomy
5. No distant metastases or gastric stump cancer
6. No other malignant tumors

Exclusion Criteria:

1. Patients who had undergone neoadjuvant chemotherapy or radiotherapy
2. Patients who received capecitabine or S-1 alone or combined with biological therapy, radiation therapy, or Immunosuppressive therapy