Yes, it may soon come down to that choice. Massachusetts Institute of Technology bioengineer Sangeeta Bhatia and her research team have engineered a yogurt that is capable of testing for colorectal cancer, Bhatia told MIT Technology Review. Basically a bacteria in the yogurt is modified to interact with tumors and produce nanoparticles that carry biomarkers of cancer. You eat the yogurt, and the nanoparticles are excreted in urine and can be detected using a paper-based antibody test. Injections of the nanoparticles have worked in mice so far, identifying both colorectal cancer and blood clots, but the yogurt is an easier way to get them into the body.