Regional differences in advanced gastric cancer: exploratory analyses of the AVAGAST placebo arm

Background: AVAGAST was an international, randomized, placebo-controlled phase III study of chemotherapy with or without bevacizumab as first-line therapy for patients with advanced gastric cancer. We performed exploratory analyses to evaluate regional differences observed in the trial. Methods: Analyses were performed in the placebo plus chemotherapy arm (intention-to-treat population). Chemotherapy was cisplatin 80 mg/m² for six cycles plus capecitabine (1000 mg/m² orally bid days 1–14) or 5-fluorouracil (800 mg/m²/day continuous IV infusion days 1–5) every 3 weeks until disease progression or unacceptable toxicity. Results: Overall, 387 patients were assigned to placebo plus chemotherapy (eastern Europe/South America, n = 118; USA/western Europe, n = 81; Korea/other Asia, n = 94; Japan, n = 94). At baseline, poor performance status, liver metastases, and larger tumors were most frequent in eastern Europe/South America and least frequent in Japan. Patients received subsequent chemotherapy after disease progression as follows: eastern Europe/South America (14%); USA/western Europe (37%); Korea/other Asia (61%); and Japan (77%). Hazard ratios for overall survival versus USA/western Europe were 1.47 (95% CI, 1.09–1.99) for eastern Europe/South America, 0.91 (95% CI, 0.67–1.25) for Korea/other Asia, and 0.87 (95% CI, 0.64–1.19) for Japan. Conclusions: Regional differences in the healthcare environment may have contributed to the differences in overall survival observed in the AVAGAST study.