Since the point-to-set maps were introduced by Zangwill in the study of conceptual algorithms, various sufficient conditions for the algorithms to be of global convergence have been established.In this paper, the rela...Since the point-to-set maps were introduced by Zangwill in the study of conceptual algorithms, various sufficient conditions for the algorithms to be of global convergence have been established.In this paper, the relations among all these conditions are illustrated by a unified approach;still more, unlike the sufficient conditions previously given in the literature,a new necessary condition is put forward at the end of the paper, so that it implies more applications.展开更多
BACKGROUND：Progression-free survival（PFS）has not been extensively investigated as a surrogate for survival in the firstline treatments of pancreatic cancer.The aim of this review was to evaluate PFS as a potential ...BACKGROUND：Progression-free survival（PFS）has not been extensively investigated as a surrogate for survival in the firstline treatments of pancreatic cancer.The aim of this review was to evaluate PFS as a potential surrogate endpoint for overall survival（OS）in advanced pancreatic cancer in trials comparing poly-chemotherapy to gemcitabine alone.DATA SOURCES： A systematic literature search in PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials was conducted. The key words included randomized trial, first-line chemotherapy, pancreatic cancer, gemcitabine and poly-chemotherapy. Adjusted weighted linear regression was used to calculate Rs （Spearman＇s rank-order correlation coefficient） between PFS and post-progression survival （PPS） with OS （Rs） and between treatment effects on PFS and OS （RHR）. RESUEFS： A total of 30 trials including 8467 patients met the inclusion criteria. Correlation between the treatment effects on PFS and OS （RHR=0.78） and between the endpoint PFS and OS was high across all studies （Rs=0.75）. The slope of the re- gression line was 0.76±0.26, indicating that an agent produc- ing a 10% risk reduction for PFS will provide a 7.6%±2.6% risk reduction for OS. Correlation between PPS and OS was very strong （Rs=0.71） and accounted for more than 50% of the whole OS variability （R2=0.57）. CONCLUSION： Because of the robust correlation with OS and the potential influence of PPS caused by the second line therapies, it may be justified to consider PFS as a surrogate endpoint in trials evaluating new cytotoxic agents when gemcitabine is the control arm.展开更多
文摘Since the point-to-set maps were introduced by Zangwill in the study of conceptual algorithms, various sufficient conditions for the algorithms to be of global convergence have been established.In this paper, the relations among all these conditions are illustrated by a unified approach;still more, unlike the sufficient conditions previously given in the literature,a new necessary condition is put forward at the end of the paper, so that it implies more applications.
文摘BACKGROUND：Progression-free survival（PFS）has not been extensively investigated as a surrogate for survival in the firstline treatments of pancreatic cancer.The aim of this review was to evaluate PFS as a potential surrogate endpoint for overall survival（OS）in advanced pancreatic cancer in trials comparing poly-chemotherapy to gemcitabine alone.DATA SOURCES： A systematic literature search in PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials was conducted. The key words included randomized trial, first-line chemotherapy, pancreatic cancer, gemcitabine and poly-chemotherapy. Adjusted weighted linear regression was used to calculate Rs （Spearman＇s rank-order correlation coefficient） between PFS and post-progression survival （PPS） with OS （Rs） and between treatment effects on PFS and OS （RHR）. RESUEFS： A total of 30 trials including 8467 patients met the inclusion criteria. Correlation between the treatment effects on PFS and OS （RHR=0.78） and between the endpoint PFS and OS was high across all studies （Rs=0.75）. The slope of the re- gression line was 0.76±0.26, indicating that an agent produc- ing a 10% risk reduction for PFS will provide a 7.6%±2.6% risk reduction for OS. Correlation between PPS and OS was very strong （Rs=0.71） and accounted for more than 50% of the whole OS variability （R2=0.57）. CONCLUSION： Because of the robust correlation with OS and the potential influence of PPS caused by the second line therapies, it may be justified to consider PFS as a surrogate endpoint in trials evaluating new cytotoxic agents when gemcitabine is the control arm.
