Lower left abdominal pain can be seen in ulcerative colitis, colon cancer, etc. Anal pain can be seen in hemorrhoids, anal fissure, etc. Therefore, lower left abdominal pain and anal pain are not necessarily bowel cancer. 1. Ulcerative colitis: it is a kind of chronic non-specific intestinal inflammation, and its main symptoms include diarrhea, mucus, pus and blood stools, abdominal pain, etc., in which abdominal pain is mostly in the left lower abdomen. 2. Colon cancer: it is a kind of malignant tumor in gastrointestinal tract, and its main symptoms include change of defecation habit and fecal character, abdominal pain (with inaccurate localization), abdominal mass, intestinal obstruction and other manifestations. 3. Hemorrhoids: divided into internal hemorrhoids, external hemorrhoids, mixed hemorrhoids. The main symptom of external hemorrhoids is severe pain in the perianal area. 4. Anal fissure: it is a skin crack of the anal canal, and the typical symptoms are perianal pain, constipation, blood in stool, etc. The main symptoms of anal fissure are pain in the perianal area, constipation, blood in stool and so on. Lower left abdominal pain and anal pain are not necessarily colorectal cancer, but you should seek medical attention in time to receive regular examination and treatment to avoid delay.