Received: 16 March 2018
Accepted: 26 April 2018
First Online: 11 May 2018
Ethics approval and consent to participate
: This retrospective study was approved by the Institutional Review Board at The University of Texas MD Anderson Cancer Center. Waiver of informed consent was granted because there was minimal risk to subjects as A) this study retrospectively reviewed data collected from patients as part of established or routine standard of care, B) no diagnostic or therapeutic interventions were performed, C) no patient contact was involved, D) consent was impractical to obtain from some patient because they were lost to follow-up or deceased.
: The authors declare that they have no competing interests.
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