Rectal cancer has a high incidence in China. The misdiagnosis rate is as high as 30% because the early symptoms are not typical or even asymptomatic. After a lot of clinical observation, doctors have summarized 10 symptoms, which can be regarded as the danger signals of rectal cancer: 1.Anemia of unknown cause. 2. Sudden weight loss. 3.Abdominal distension, abdominal pain, indigestion and loss of appetite. 4.Lumps in the anus or abdomen. 5.Blood in the stool or black stool. 6.Pus, blood and mucus in the stool. 7.Changes in stool habits, increased frequency or diarrhea, urgency and heaviness. 8.Diarrhea and constipation alternate. 9.Changes in the shape of stool, becoming thin, flattened or with grooves. 10.Multiple polyps or papillary adenomas are found. In case of the above, you should immediately go to the hospital for examination to avoid misdiagnosis or omission and delay in treatment.