Postoperative adjuvant therapy with the oral fluoropyrimidine derivative S-1 improved overall survival and relapse-free survival in patients with stage II or III gastric cancer who had D2 gastrectomy. Five-year survival rates in the phase III study were 71.7% for patients in the S-1 group vs 61.1% in the surgery-only group, and the relapse-free survival rates were 65.4% vs 53.1%, respectively. Results were reported in the Journal of Clinical Oncology.
Patients eligible for the Adjuvant Chemotherapy Trial of S-1 for Gastric Cancer (ACTS-GC) had histopathologically confirmed diagnoses of stage II (except for T1 disease), IIIA, or IIIB gastric cancer; R0 resection (with no tumor cells at the margin) with D2 or more extensive lymph node dissection; and no evidence of hepatic, peritoneal, or distant metastasis and no tumor cells in peritoneal fluid on cytologic analysis. A total of 1,059 patients were enrolled at 109 centers throughout Japan, and 529 were assigned to the S-1 group and 530 to the surgery-only group. In both groups combined, 44.8% had stage II disease, 38.6% had stage IIIA disease, and 16.5% had stage IIIB disease.
Patients in the S-1 group received an 80- to 120-mg daily dose of the drug, assigned on the basis of body surface area, in two divided doses for 4 weeks, followed by 2 weeks of rest. Treatment continued for 1 year after surgery. Patients assigned to the surgery-only group received no anticancer treatment postoperatively until the confirmation of recurrence.
“Our present results confirmed that postoperative adjuvant chemotherapy with S-1 alone reduced the risk of death by 33.1%,” the researchers stated. “This reduction in the risk of mortality is comparable with that obtained with combined regimens for adjuvant chemotherapy in the Medical Research Council Adjuvant Gastric Infusional Chemotherapy (MAGIC) trial and the Intergroup 0116 (INT-0116) trial.”
The authors said that it remains uncertain whether the results of the ACTS-GC trial can be extrapolated to countries outside East Asia “because of possible differences in pharmacokinetics of S-1 between whites and East Asians” and because more limited surgery is performed for these cancers in Europe and the United States. ■
Sasako M, et al: J Clin Oncol 29:4387-4393, 2011.