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Disease-free survival as a surrogate for overall survival in neoadjuvant trials of gastroesophageal adenocarcinoma: Pooled analysis of individual patient data from randomised controlled trials
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12 2019
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Source: Eur J Cancer. 123:101-111
Details:
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Alternative Title:Eur J Cancer
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Personal Author:
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Description:Introduction:
Disease-free survival (DFS) is increasingly being used as surrogate end-point for overall survival (OS) in cancer trials. So far, there has been no validation of the surrogacy of DFS for OS for neoadjuvant treatment of gastroesophageal adenocarcinoma.
Methods:
The study uses individual patient data (IPD) from eight randomised controlled trials (RCTs) (n = 1126 patients) comparing neoadjuvant therapy followed by surgery with surgery alone for gastroesophageal adenocarcinoma. Correlation between OS time and DFS time was calculated to evaluate individual-level surrogacy. For each trial, survival curves using the Kaplan-Meier method were plotted and hazard ratios (HRs) on the treatment effects were calculated for OS and DFS separately. Those HRs were pooled in a random-effects meta-analysis. Observed HRs were compared with predicted HRs for OS using results from an error-invariables linear regression model accounting for the uncertainty about the estimated effect. The strength of the association was quantified by the coefficient of determination to assess trial-level surrogacy. The surrogate threshold effect was calculated to determine the minimum treatment effect on DFS necessary to predict a non-zero treatment effect on OS.
Results:
A strong correlation between OS time and DFS time was observed, indicating a high individual-level surrogacy. For all RCTs, estimated HRs for OS and DFS were highly similar. In the meta-analysis, the overall HR for OS was virtually identical to that for DFS. The estimated coefficient of determination r2 for the association between HRs for OS and DFS was 0.912 (95% confidence interval: 0.75−1.0), indicating a very good fit of the regression model and thus a strong trial-level surrogacy between OS and DFS. The surrogate threshold effect based on the regression analysis was 0.79.
Discussion:
Based on strong correlations between DFS and OS, as well as a strong correlation of the treatment effects of the two end-points in the error-in-variable regression, DFS seems an appropriate surrogate marker for OS in randomised trials of neoadjuvant chemotherapy or chemoradiotherapy for gastroesophageal adenocarcinoma.
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Pubmed ID:31678767
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Pubmed Central ID:PMC8767957
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Volume:123
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