6060^ Background: The phase 3 placebo-controlled DECISION trial established that sorafenib treatment significantly improves progression-free survival for patients with RAI-rDTC. Overall survival (OS) was immature at the time of primary analysis and possibly confounded by placebo crossing over to receive open-label sorafenib at progression. We report the OS results from a planned 9-month follow up as of May 31, 2013 and possible corrections for the crossover. Methods: Patients with locally advanced/metastatic progressive RAI-rDTC were randomized to receive sorafenib or placebo. Placebo patients were allowed to receive sorafenib open-label (OL) upon progression. OS data were analyzed using 2 correction methods for cross over: iterative parameter estimation (IPE) and rank preserving structural failure time (RPSFT). Results: A total of 417 patients were randomized (207 to sorafenib and 210 to placebo). Median OS had not been reached at the time of primary analysis (August 31, 2012) at which time 70% of placeb...