Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.|Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.|Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.|Department of Bioinformatics & Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.|Department of Biostatistics, University of Michigan, Ann Arbor, MI 48109, USA.