Gastric cancer patients generally have poor digestive function, which will cause symptoms such as acid reflux, heartburn, nausea and vomiting, etc. It will also affect the saliva secreted in the mouth, which cannot be swallowed normally, and together with the gastric juice flowing back into the mouth, the mixture will accumulate in the mouth and form sticky phlegm, which is the main reason for stomach cancer patients to spit up sticky phlegm. After the tumor of gastric cancer shrinks, the patient’s digestive function will improve and saliva will enter the gastrointestinal tract smoothly, so the spitting of sticky phlegm will be reduced. Stomach cancer patients with low immunity will have more mucous phlegm if there is infection in the lungs, so anti-infection treatment is needed.