- Follow-up phase: Patients undergo core tissue biopsies at baseline and at 3 months for genomic and gene expression analysis. Insulin-like growth factor 1 (IGF-1) and selenium-binding protein 1 levels are measured by quantitative reverse transcription-polymerase chain reaction (PCR). Patients also undergo blood sample collection periodically for biomarker analysis, proteomic analysis, and for telomere length and telomerase activity analysis as measured by quantitative PCR and telomerase repeat amplification protocol (TRAP). Blood and urine samples are also collected and stored for future analysis.