Cancer constitutes an increasing risk factor for the ageing population in the developed world. The following graph shows the death rates per 100'000 in the ten worst countries (World Cancer Reserch Fund, 2011).

Estimates predict more than 500'000 cancer victims in the US for the year 2015 alone (American Cancer Society, Surveillance Research, 2015). While these estimates include only the four major cancers (colon & rectum, lung & bronchus, breast and prostate), other manifestations of cancer are on the rise as well.

Current tests for cancer screening mostly rely on imaging methods to detect tumors in various tissues. For many cancer types there is no method to detect metastasis at an early stage (US Centers of Disease Control and Prevention, 2015).