There's usually going to be some signal though even if it was just localized downregulation of some proteins on immune cells induced by a cancer to escape detec

There's usually going to be some signal though even if it was just localized downregulation of some proteins on immune cells induced by a cancer to escape detection. The trouble there is that may be swamped in a systemic serum sample. Looking at subsets are more useful to improve signal to noise ratio like looking at extracellular vesicles released by tumour and immune cells for messaging purposes