Abstract: Aptamers for use in the capture, diagnosis, enumeration and eradication of circulating tumor cells; an aptamer immobilized microfluidic chips for use in a rapid and non-invasive method of testing for cancer by capturing and detecting circulating tumor cells through the use of the aptamers immobilized microfluidic chips, and screening high risk patients for cancer thereby allowing the disease to be identified at the early stage where the prognosis of survival is the highest; and a non-invasive method of treating cancer by capturing and eradicating circulating tumor cells through the use of aptamer-photosensitizer conjugates injected into a patient's bloodstream and excited by a laser.