Phase III study of cisplatin with or without S-1 in patients with stage IVB, recurrent, or persistent cervical cancer

Background: This open-label phase III trial evaluated efficacy and safety of S-1 plus cisplatin vs. cisplatin alone as first-line chemotherapy in patients with stage IVB, recurrent, or persistent cervical cancer. Methods: Patients were randomised (1:1) to S-1 plus cisplatin (study group) or cisplatin alone (control group). In each cycle, cisplatin 50 mg/m² was administered on Day 1 in both groups. S-1 was administered orally at 80–120 mg daily on Days 1–14 of a 21-day cycle in the study group. The primary endpoint was overall survival (OS). Results: A total of 375 patients were enrolled, of whom 364 (188, study group; 176, control group) received treatment. Median OS was 21.9 and 19.5 months in the study and control groups, respectively (log-rank P = 0.125; hazard ratio [HR] 0.84, 95% confidence interval [CI] 0.67–1.05). Median progression-free survival (PFS) was 7.3 and 4.9 months in the study and control groups, respectively (HR 0.62, 95% CI 0.48–0.80, P < 0.001). The adverse event (AE) rate increased in the study group despite the absence of any unexpected AEs. Conclusions: S-1 plus cisplatin did not show superiority over cisplatin alone in OS but significantly increased PFS in patients with stage IVB, recurrent, or persistent cervical cancer. Since the standard therapy has changed in the course of this study, further studies are warranted to confirm the clinical positioning of S-1 combined with cisplatin for this population.