Funding for this research was provided by:
Received: 5 September 2018
Accepted: 3 December 2018
First Online: 13 December 2018
Ethics approval and consent to participate
: The MD Anderson Cancer Center Institutional Review Board has reviewed and approved this retrospective study and a waiver of informed consent was obtained.
: Not applicable.
: The authors declare that they have no competing interests. IR is a consultant and speaker with Pfizer.IR, A-MC and RH are recipients of Pfizer study grants over the last 5 years.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.