Postprogression therapy and confounding for the estimated treatment effect on overall survival in phase III oncology trials oleh Pavlos Msaouel, Ramez Kouzy, Joseph Abi Jaoude, Ethan B Ludmir, Alexander D Sherry, Timothy A Lin, Esther J Beck, Avital M Miller, Adina H Passy, Gabrielle S Kupferman, Eugene J Koay, Clifton David Fuller, Charles R Thomas, Zachary R McCaw