Surrogacy of intermediate endpoints for overall survival in randomized controlled trials of first-line treatment for advanced soft tissue sarcoma in the pre- and post-pazopanib era: a meta-analytic evaluation

Table 4 Correlations between surrogate endpoints and OS

Surrogate endpoint	RCTs before 2012 (1974–2012)	RCTs after 2012 (2013–2017)	Total RCTs
Surrogate endpoint	R² (95% CI)	R² (95% CI)	R² (95% CI)
PFS	0.459 (0.216–0.774)	0.586 (0.319–0.852)	0.557 (0.326–0.788)
3-month PFS	0.103 (0.0–0.332)	0.255 (0.0–0.572)	0.200 (0.0–0.453)
6-month PFS	0.344 (0.037–0.651)	0.386 (0.064–0.708)	0.073 (0.0–0.250)
RR	0.357 (0.064–0.650)	0.228 (0.0–0.539)	0.278 (0.020–0.536)

Abbreviations: CI, confidence interval; HR, hazard ratio; OR, odds ratio; OS, overall survival; PFS, progression-free survival; RCT, randomized controlled trial; RR, response rate

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