Why Cancer Lights Up on a PET Scan Ever wonder why a PET scan is so good at finding cancer? It’s because cancer cells love sugar. A PET (Positron Emission Tomography) scan uses a radioactive form of glucose to highlight areas of high sugar uptake in the body. Since cancer cells consume glucose at a much higher rate than normal cells, they "light up" on the scan like a beacon. This isn't just useful for diagnosis—it's a powerful insight into how cancer survives. These cells thrive on sugar, which