Circulating tumor DNA In a study in China, 46 of 126 primary breast cancer pts have p53 mutation in the peripheral blood Clin Cancer Res 2001;7:2222-2227
Circulating tumor DNA Specific mutation and structural variation in primary tumor cell 142 breast cancer pts ( not disseminated) was analyzed at diagnosis Clin Cancer Res 2002;8:3761-3766.
Method Prospective, single-center study Compare circulating tumor DNA, CA 15-3, circulating tumor cell Tagged-amplicon deep sequencing for PIK3CA (encoding the phosphatidylinositol-4,5-bisphosphate 3- kinase, catalytic subunit alpha protein) and TP53 (encoding tumor protein p53) or paired-end whole- genome sequencing p53 mutations are found in 50–75% of breast carcinoma patients Serial blood samples(30ml) every 3 or more weeks Science (Wash. DC), 253: 49–53, 1991.
Identification of Genome Alteration Tagged-amplicon deep sequencing Paired-end whole-genome sequencing
Conclusion Circulating tumor DNA shows superior sensitivity and has a greater dynamic range that correlates with tumor burden Circulating tumor DNA provide earliest measure of treatment response Identification of somatic alteration is needed Target sequencing could be expanded in addition to PIK3CA and TP53 when the cost reduced There are many ways to identify tumor DNA : digital PCR assay, targeted deep sequencing, exome sequencing, BEAMing, Safe-SeqS…
Future Target like BCR/ABL may be found and develop new target therapy!!