Total gastrectomy increases the incidence of grade III and IV toxicities in patients with gastric cancer receiving adjuvant TS-1 treatment

BACKGROUND: We aimed to evaluate the safety and efficacy of TS-1 adjuvant chemotherapy in Taiwanese patients with gastric cancer. METHODS: We included in this study patients with locally advanced gastric cancer who received adjuvant TS-1 or 5-fluorouracil chemotherapy after curative surgery and extended lymph node dissection between 1 June 2008 and 31 December 2012 at Chang Gung Memorial Hospital. Patient characteristics, tumor features, safety profiles and compliance with TS-1 treatment were retrospectively analyzed from medical charts. RESULTS: Forty patients received adjuvant chemotherapy with TS-1 and 193 with 5-fluorouracil within the study period. The 1- and 2-year overall survival rates were 90.6% and 87% in the TS-1 group and 95.4% and 86.8% in the 5-fluorouracil group (P = 0.34). The 1- and 2-year disease-free survival rates were 90.6% and 74.7% in the TS-1 group and 88% and 75.7% in the 5-fluorouracil group (P = 0.66). In the TS-1 group, tumor recurrence was more frequent in those with >15 metastatic lymph nodes than ≤15. Overall, 78.9%, 74.3%, 62.1% and 56% of patients underwent TS-1 treatment for at least 3, 6, 9 and 12 months, respectively. The most common adverse events of TS-1 were skin hyperpigmentation (55%), diarrhea (27.5%), dizziness (27.5%) and leucopenia (20%). Severe adverse events (SAEs; grade III or IV toxicity) were diarrhea (7.5%), stomatitis (7.5%), leukopenia (5%), vomiting (2.5%), anorexia (2.5%) and dizziness (2.5%). Patients who underwent total gastrectomy had a significantly greater risk of TS-1-related SAEs than patients who underwent subtotal gastrectomy (40% versus 8%, P = 0.014). CONCLUSIONS: The incidence of SAEs during TS-1 therapy was more common in Taiwanese patients with gastric cancer who underwent total gastrectomy compared with those who underwent subtotal gastrectomy. Clinicians must be aware of and able to manage these SAEs to maximize patient compliance with adjuvant TS-1.