When clinical symptoms such as diarrhea or constipation, changes in bowel habits, bloody stools, and abdominal pain occur, we should be vigilant about the possibility of rectal cancer. The examination for rectal cancer can start with a digital rectal exam, especially for low-lying rectal cancer, which is closer to the anus; these tumors can be detected through this method. Then, a colonoscopy should be performed to take a biopsy to confirm the diagnosis, which is the gold standard for confirmation. Additionally, blood tests for tumor markers can be conducted. Generally, carcinoembryonic antigen (CEA) and CA199 levels may be elevated, but this is not absolute as their specificity and sensitivity are not very high. An enhanced CT scan of the abdomen can also be done. In such scans, we can see thickening of the intestinal wall where the tumor is located, and the enhancement can show the intensified thickening of the intestinal wall. Combining all these methods can confirm the diagnosis of rectal cancer.