Table I:

terms and definitions of the steps of the metastatic process required to understand the windows of opportunity that are available to counter it.

Term	Definition
Primary tumor	The original cancer within the tissue of origin.
Dissemination	The process by which cancer cells spread from the primary tumor to other sites.
Disseminated cancer	Cancer that has spread from the primary tumor to other sites in the body. It may or may not be detectable and it may be proliferative (active) or dormant (see below)
Metastasis	The formation of secondary cancer growth(s) in other sites in the body. This process involves dissemination, entry into distant sites and growth in these locations.
Dormant disseminated cancer	Disseminated tumor cells located at sites that are separate from the primary tumor, and which are not increasing in numbers to form an overt metastasis. They exist as solitary cancer cells or very small groups of cells over long periods of time. Although not detectable by traditional clinical methods, they can sometimes be detected by more sensitive experimental methods such as liquid biopsies.
Overt Metastases	Disseminated cancer that has grown sufficiently to be detectable by conventional imaging methods (e.g. MRI), or that can be tracked by established biomarkers (e.g. PSA in prostate cancer) and confirmed by imaging. These metastases cause clinical symptoms and can be lethal.
Liquid Biopsy	A sample obtained from blood, a bone marrow aspirate or other bodily fluids. In these biopsies, cells that are in the blood (circulating tumor cells) or that have lodged in the bone marrow can be detected and analyzed at a single cell resolution. The non-cellular component from both samples can be tested for protein biomarkers, exosomes, or cell-free RNA and DNA, which can be used for patient monitoring.