Background: S-1 monotherapy is one of the standard adjuvant treatments for patients with stage II and III gastric cancers. Early recurrence after S-1 adjuvant therapy has a poor prognosis. This study aimed to clarify the treatment outcomes of systemic chemotherapy and explore encouraging regimens.
Methods: This was a multicenter retrospective study. Among gastric cancer patients who underwent curative gastrectomy followed by adjuvant S-1 monotherapy, patients who experienced a recurrence while receiving adjuvant therapy or within 6 months after completion and started systemic chemotherapy at four institutions between 2005 and 2015 were eligible.
Results: A total of 112 patients were included. The main treatment regimens were weekly paclitaxel (n = 38, 34%), irinotecan plus cisplatin (n = 31, 28%), capecitabine plus cisplatin (n = 7, 6%), and irinotecan monotherapy (n = 6, 5%). For all patients, median progression-free survival and overall survival were 3.7 and 11.4 months, respectively. Among 77 patients with measurable lesions, the overall response and disease control rates were 24.7% and 62.3%, respectively. Multivariate analyses for overall survival showed that Eastern Cooperative Oncology Group performance status 2 [hazard ratio (HR) 3.71; 95% confidence interval (CI) 1.78-7.73] and undifferentiated histological type (HR 2.04; 95% CI 1.35-3.44) were independent prognostic factors, and treatment regimens were not prognostic. Exploratory comparisons did not show statistically significant differences between treatment regimens.
Conclusions: This study of the largest number of patients with early recurrence after S-1 adjuvant monotherapy demonstrated that the prognosis for patients treated by all regimens was similar and poor.
Keywords: Adjuvant chemotherapy; Gastric cancer; Recurrence.