To prevent metastasis you would need to be permanently linked-up to this machine. It is more likely to find uses in diagnostics, where you would be able to detect abnormal cells, or cells that have been tagged with a diagnostic tool such as a specially-targeted antibody, in a blood sample that are too rare to be detected by current methods (except PCR).

The original paper also proposes uses in "imaging and detection of bioparticles of interest in oceanography (e.g., phytoplanktons), energy science (e.g., oil emulsions and engineered microbes), environmental science, food science, cosmetics, pharmaceutics, and medicine."