Are cells found in the peripheral blood and those isolated from cancer tissue different?

Related: I assume you are talking about single cancer cells isolated in the circulation from patients with cancer. These are derived from the cancer and so are the same in many ways from cancer cells in the tissue, but because they are detached and circulating they may have some different characteristics as well. They may behave more like cancer stem cells.

Ongoing research : This is a subject of ongoing research. There are several technologies involved and comparative studies trying to define the best markers of cancer that can be studies from peripheral blood including cancer cell , dna, RNA and protein detection technologies.