In addition to autoimmune and infectious diseases, blood transcript profi ling studies have been carried out in the cancer research fi eld. While hematological malignancies have led the way (reviewed in [92] ), blood profi les have also been obtained more recently from patients with solid organ tumors [93] . Notably, these signatures can refl ect not only the immunological or physiological changes eff ected by cancers but also the presence of rare tumor cells in the circulation [94] [95] [96] .