In this review, we focus on post-progression survival after first-line chemotherapy of advanced gastric cancer, and particularly the differences between Japan and the rest of the world. We reviewed 15 recent phase III trials of which 4 were solely recruited from Japanese and 11 from rest of the world. The patient characteristics age, performance status, previous gastrectomy and the number of metastatic sites were similar in Japan and rest of the world. However, the diffuse histological type was more common in Japan. While overall survival was longer in Japan (10.5-14.1 vs. 7.9-12.2 months), progression-free survival tended to be shorter in Japan (3.6-6.0 vs. 3.1-7.4 months). Post-progression survival calculated as the difference between median overall survival and progression-free survival was clearly longer in Japan (6.9-8.6 vs. 2.4-6.2 months). The proportion of patients receiving second-line chemotherapy (%2nd-CX) was quite different in Japan and rest of the world (69-85% vs. 11-59%). Correlations between %2nd-CX and post-progression survival were strong (Spearman's rank correlation coefficient; ρ = 0.86, P < 0.001). Correlations between %2nd-CX and ratio of post-progression survival to total overall survival were also strong (ρ = 0.84, P < 0.001). Because a survival benefit of second-CX was documented in several phase III trials, it can be concluded that higher %2nd-CX partly contributed to extended post-progression survival. However, considering that second-CX increased survival only by ~1.5 months at median, other factors such as third-line chemotherapy may have some influences to prolonged post-progression survival.
Keywords: chemotherapy; gastric cancer; post chemotherapy; post-progression survival; second-line chemotherapy; third-line chemotherapy.
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