  A key focus in current cancer research is the discovery of cancer biomarkers
that allow earlier detection with high accuracy and lower costs for both
patients and hospitals. Blood samples have long been used as a health status
indicator, but DNA methylation signatures in blood have not been fully
appreciated in cancer research. Historically, analysis of cancer has been
conducted directly with the patient's tumor or related tissues. Such analyses
allow physicians to diagnose a patient's health and cancer status; however,
physicians must observe certain symptoms that prompt them to use biopsies or
imaging to verify the diagnosis. This is a post-hoc approach. Our study will
focus on epigenetic information for cancer detection, specifically information
about DNA methylation in human peripheral blood samples in cancer discordant
monozygotic twin-pairs. This information might be able to help us detect cancer
much earlier, before the first symptom appears. Several other types of
epigenetic data can also be used, but here we demonstrate the potential of
blood DNA methylation data as a biomarker for pan-cancer using SAS 9.3 and SAS
EM. We report that 55 methylation CpG sites measurable in blood samples can be
used as biomarkers for early cancer detection and classification.
