Safety evaluation of oral fluoropyrimidine S-1 for short- and long-term delivery in advanced gastric cancer: analysis of 3,758 patients.

To evaluate the comprehensive safety profile of S-1, a promising novel oral fluoropyrimidine derivative, based on large cohort data. Study subjects were identified from a prospective registry of 3,758 advanced gastric cancer patients in Japan. Each patient was treated with an identical regimen of S-1 monotherapy (40 mg b.i.d. on days 1–28, every 6 weeks) and assessed for all adverse events. The median duration of treatment was 88 days; 1,605 (43%) patients underwent three or more treatment cycles. The relative dose intensity was 0.87 in the first two cycles (short-term treatment period) and 0.89 thereafter (long-term treatment period). Neutropenia was the most common severe (grade 3–4) hematological event (6.3% in the short-term period and 5.3% in the long-term period). Other hematological or key gastrointestinal events (diarrhea, nausea/vomiting, and stomatitis) had a low incidence of severe cases throughout the whole administration period (0.3–3.8%). The time to onset of severe events did not differ between patients with mild renal impairment (creatinine clearance, 50–79 ml/min) and those with normal renal function (≥80 ml/min) (hazard ratio, 1.04; 95% CI, 0.87–1.23; P = 0.691). S-1 had manageable severe toxicity and allowed good compliance regardless of treatment duration. Prolonged administration of the drug was sustainable. [ABSTRACT FROM AUTHOR]