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.