Frequent outgassing is not a precursor of cancer. Frequent outgassing is sometimes not a disease at all, but a personal habit that has a lot to do with one’s dietary habits and with one’s physique. If the protein content in the diet structure is relatively high, such as refined meat, eggs eat more, protein decomposition will produce a lot of gas, there will be increased exhaust. There is another kind of vegetable such as water radish and onion, which can also increase gas emission and has nothing to do with precancerous signs. The signs before cancer are usually not too obvious. The early symptoms of colon and rectal cancers of digestive system are change in stool habit, positive fecal occult blood, increased number of stools, unformed stools, and no clear typical clinical symptoms.