Rectal cancer occurs when cancerous cells develop in the tissue of the rectum. The rectum is the last part of the large intestine and leads to the anus, which is the opening to the outside of the body. Body waste is stored in the rectum until it is eliminated from the body through the anus.
Although rectal cancer is a life-threatening disease, it is a highly curable form of cancer if found early. Therefore, regular check-ups and screenings are very important.
Although the exact cause of rectal cancer is unknown, certain risk factors have been identified that may increase a person's chance of developing the disease. These include:
- Age. The majority of rectal cancers are diagnosed in people aged 50 or older, although the disease affects all ages.
- Bowel disease. A history of colorectal cancer, intestinal polyps, and diseases such as chronic ulcerative colitis, Crohn's disease and inflammatory bowel disease increase a person's chance of developing rectal cancer.
- Diet and exercise. A diet high in fat, particularly from animal sources, and an inactive, sedentary lifestyle can increase a person's chance of developing rectal cancer.
- Ethnic background and race. Jews of Eastern European descent, called Ashkenazi Jews, have a higher rate of rectal cancer. African-Americans and Hispanics have a higher death rate caused by rectal cancer, which may be caused by insufficient screenings, poor diet and lack of exercise.
- Family history/genetic factors. Specific genes have been identified that significantly increase a person's chance of having rectal cancer. People with a strong family history of colorectal cancer, as defined by cancer or polyps in a first-degree relative younger than 60 or two first-degree relatives of any age, are also at increased risk for developing rectal cancer.
- Smoking and alcohol. Research suggests that smokers and heavy drinkers have an increased chance of developing rectal cancer.
Our approach to rectal cancer
Colorectal cancer specialists at UCSF have decades of experience with diagnosing and treating rectal cancer. We focus on providing the most effective care for each individual patient. Surgery is the most common treatment for all stages of rectal cancer, and we use the latest surgical approaches. Many patients will also have radiation, chemotherapy or a combination of the two.
In addition to treating people at every stage of rectal cancer, our team often handles complicated or unusual cases that other hospitals turn away. We also offer opportunities to try experimental treatments by joining a clinical trial.
Awards & recognition
Among the top hospitals in the nation
Best in Northern California and No. 7 in the nation for cancer care
Designated comprehensive cancer center
Signs & symptoms
Common signs and symptoms of rectal cancer include:
- A change in bowel habits
- Diarrhea, constipation, or feeling that the bowel does not empty completely
- Blood, either bright red or very dark in the stool
- Stools that are narrower than usual
- General abdominal discomfort such as frequent gas pains, bloating, fullness or cramps
- Weight loss with no known reason
- Constant tiredness
In making a diagnosis of rectal cancer, your doctor will first start by recording your medical history, asking about any symptoms you may be experiencing and conducting a thorough physical examination. He or she also may recommend one or more of the following diagnostic tests:
- Digital rectal exam. This exam involves the doctor or nurse inserting a gloved, lubricated finger into the rectum to feel for an abnormalities.
- Barium enema. Also known as a lower gastrointestinal series, this test involves taking X-rays of the large intestines.
- Fecal occult blood test. This is a noninvasive test that detects the presence of hidden, or occult blood in the stool. Such blood may arise from anywhere along the digestive tract. Hidden blood in the stool is often the first, and in many cases the only, warning sign that a person has colorectal cancer.
- Sigmoidoscopy. Sigmoidoscopy is performed to see inside the rectum and the lower colon and remove polyps or other abnormal tissue for examination under a microscope.
- Colonoscopy. Colonoscopy is performed to see inside the rectum and the entire colon and remove polyps or other abnormal tissue for examination under a microscope.
- Polypectomy. Polypectomy is performed during a sigmoidoscopy or colonoscopy to remove polyps.
- Biopsy. In a biopsy, a small amount of tissue from the suspected area is removed for examination by a pathologist to make a diagnosis.
If you are diagnosed with rectal cancer, your doctor needs to learn the stage or extent of your disease. Staging is a careful attempt to find out whether the cancer has spread and if so, to what parts of the body. This information also helps your doctor develop the best and most effective treatment plan for your condition. More tests – in particular an endorectal ultrasound (ERUS) or a magnetic resonance imaging (MRI) – may be performed to help determine the stage.
The various stages of rectal cancer include:
- Stage 0. The cancer is very early. It is found only in the innermost lining of the rectum.
- Stage I. The cancer involves more of the inner wall of the rectum.
- Stage II. The cancer has spread outside the rectum to nearby tissue, but not to the lymph nodes. Lymph nodes are small, bean-shaped structures that are part of the body's immune system.
- Stage III. The cancer has spread to nearby lymph nodes, but not to other parts of the body.
- Stage IV. The cancer has spread to other parts of the body. If it spreads, rectal cancer tends to spread to the liver and lungs.
- Recurrent. Recurrent cancer means the cancer has come back after treatment. The disease may recur in the rectum or in another part of the body.
Treatment for rectal cancer may include surgery, radiation therapy or chemotherapy, or a combination of these approaches.
Surgery is the main treatment for all stages of rectal cancer, although radiation, chemotherapy, or both are often recommended in combination.
Some patients who undergo surgery for rectal cancer require a permanent colostomy — a surgically created opening in the abdominal wall through which waste is excreted. If you have a colostomy, our specially trained nurses will help you learn how to manage the colostomy and incorporate it into your lifestyle.
Depending on the location, stage and size of your tumor, your doctor will remove your cancer with one of the following methods:
- Local excision. This surgical approach is used for very early stage cancers. It involves inserting a tube through the rectum into the colon and removing the cancer, rather than making a cut in the abdominal wall. If the cancer is found in a polyp, the procedure is called a polypectomy.
- Resection and anastomosis. This approach is used for larger and more advanced cancers and involves removing the portion if the rectum containing the cancer, as well as the fatty tissue that surrounds the rectum and contains the lymph nodes. Afterwards, the doctor will sew the colon to the remaining rectum or the anus, during a procedure called an anastomosis.
- Resection and colostomy. This approach is used when the rectum cannot be sewn back together. In these cases, a colostomy is performed, in which an opening outside of the body for waste to pass through is created, called a stoma. A bag is then placed around the stoma to collect the waste. The colostomy may be temporary, although if the entire rectum is removed, it is permanent. Our specially trained nurses will help you learn how to manage your colostomy and incorporate it into your lifestyle.
In some cases, we can remove the cancer using robotic surgery, a minimally invasive technique that can reduce recovery time and the risk of surgical complications.
Radiation therapy is the use of X-rays or other high-energy rays to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body, or external radiation therapy, or from putting materials that contain radiation through thin plastic tubes, called internal radiation therapy, in the intestine area. Radiation can be used alone or in addition to surgery and chemotherapy.
Radiation therapy may be used after surgery to kill any remaining areas of cancer or before surgery to shrink the tumor. Radiation also can be used to prevent cancer from coming back to the place it started and to relieve symptoms of advanced cancer.
Chemotherapy is the use of drugs to kill cancer cells. Chemotherapy may be taken by pill, or it may be put into the body by inserting a needle into a vein. A patient may be given chemotherapy through a tube that will be left in the vein while a small pump gives the patient constant treatment over a period of weeks.
Chemotherapy is called a systemic treatment because the drug enters the bloodstream, travels through the body, and can kill cancer cells outside the rectum.
If the cancer has spread, the patient may be given chemotherapy directly into the artery going to the newly infected part of the body. If the doctor removes all the cancer that can be seen at the time of the operation, the patient may be given chemotherapy after surgery to kill any cancer cells that are left. Chemotherapy given after an operation to a person who has no cancer cells that can be seen is called adjuvant chemotherapy.
Biological treatment, also called immunotherapy, tries to make your body fight against your cancer. It uses materials made by the body or made in a laboratory to boost, direct, or restore the body's natural defenses against disease.
UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.
More treatment info
Transanal Endoscopic Microsurgery (TEM)
Surgeons can remove certain non-cancerous and early stage rectal cancers through a minimally invasive procedure.Learn more
The procedure is equally effective, less invasive and faster than a standard colonoscopy screening for colon cancer.Learn more