Purple stools can be cancerous. The first thing to rule out when you have purple stools is whether you are eating purple foods, such as anthocyanin-rich foods like red dragon fruit, purple potatoes, purple kale, and purple beverages. If you have not eaten these foods recently and your stool appears purple, you need to check for fecal occult blood to see if it is gastrointestinal bleeding as well as check for colonoscopy to see if there is a mass in the intestines. If there is a tumor in the intestines, it can cause gastrointestinal bleeding and the possibility of purple stools. Therefore, if you have purple stools, you should not be negligent and need to go to the hospital for further examination to rule out intestinal and other digestive tract tumors.