Medical Tests

Rectal Cancer Treatment

General Information About Rectal Cancer 


  • Rectal cancer is a disease in which malignant (cancer) cells form in the tissues of the rectum. 
  • Health history affects the risk of developing rectal cancer. 
  • Signs of rectal cancer include a change in bowel habits or blood in the stool. 
  • Tests that examine the rectum and colon are used to detect (find) and diagnose rectal cancer. 
  • Certain factors affect prognosis (chance of recovery) and treatment options. 

Rectal cancer is a disease in which malignant (cancer) cells form in the tissues of the rectum. 

The rectum is part of the body’s digestive system. The digestive system takes in nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of the esophagus, stomach, and the small and large intestines.  

The colon (large bowel) is the first part of the large intestine and is about 5 feet long. Together, the rectum and anal canal make up the last part of the large intestine and are 6-8 inches long. The anal canal ends at the anus (the opening of the large intestine to the outside of the body). 

Health history affects the risk of developing rectal cancer. 

Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Talk to your doctor if you think you may be at risk for colorectal cancer. 

Risk factors for colorectal cancer include the following: 

  • Having a family history of colon or rectal cancer in a first-degree relative (parent, sibling, or child). 
  • Having a personal history of cancer of the colon, rectum, or ovary. 
  • Having a personal history of high-risk adenomas (colorectal polyps that are 1 centimeter or larger in size or that have cells that look abnormal under a microscope). 
  • Having inherited changes in certain genes that increase the risk of familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary nonpolyposis colorectal cancer). 
  • Having a personal history of chronic ulcerative colitis or Crohn disease for 8 years or more. 
  • Having three or more alcoholic drinks per day. 
  • Smoking cigarettes. 
  • Being black. 
  • Obesity. 

Older age is a main risk factor for most cancers. The chance of getting cancer increases as you get older. 

Signs of rectal cancer include a change in bowel habits or blood in the stool. 

These and other signs and symptoms may be caused by rectal cancer or by other conditions. Check with your doctor if you have any of the following: 

  • Blood (either bright red or very dark) in the stool. 
  • A change in bowel habits. 
  • Diarrhea. 
  • Constipation. 
  • Feeling that the bowel does not empty completely. 
  • Stools that are narrower or have a different shape than usual. 
  • General abdominal discomfort (frequent gas pains, bloating, fullness, or cramps). 
  • Change in appetite. 
  • Weight loss for no known reason. 
  • Feeling very tired. 

Tests that examine the rectum and colon are used to detect (find) and diagnose rectal cancer. 

Tests used to diagnose rectal cancer include the following: 

Physical exam and history 

An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits, and past illnesses and treatments will also be taken. 

Digital rectal exam (DRE) 

An exam of the rectum. The doctor or nurse inserts a lubricated, gloved finger into the lower part of the rectum to feel for lumps or anything else that seems unusual. In women, the vagina may also be examined. 


A procedure to look inside the rectum and colon for polyps (small pieces of bulging tissue), abnormal areas, or cancer. A colonoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer. 


The removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer. Tumor tissue that is removed during the biopsy may be checked to see if the patient is likely to have the gene mutation that causes HNPCC. This may help to plan treatment.  

The following tests may be used: 

Reverse transcription–polymerase chain reaction (RT–PCR) test 

A laboratory test in which the amount of a genetic substance called mRNA made by a specific gene is measured. An enzyme called reverse transcriptase is used to convert a specific piece of RNA into a matching piece of DNA, which can be amplified (made in large numbers) by another enzyme called DNA polymerase. The amplified DNA copies help tell whether a specific mRNA is being made by a gene. RT–PCR can be used to check the activation of certain genes that may indicate the presence of cancer cells. This test may be used to look for certain changes in a gene or chromosome, which may help diagnose cancer. 


A laboratory test that uses antibodies to check for certain antigens (markers) in a sample of a patient’s tissue. The antibodies are usually linked to an enzyme or a fluorescent dye. After the antibodies bind to a specific antigen in the tissue sample, the enzyme or dye is activated, and the antigen can then be seen under a microscope. This type of test is used to help diagnose cancer and to help tell one type of cancer from another type of cancer. 

Carcinoembryonic antigen (CEA) assay 

A test that measures the level of CEA in the blood. CEA is released into the bloodstream from both cancer cells and normal cells. When found in higher-than-normal amounts, it can be a sign of rectal cancer or other conditions. 

Certain factors affect prognosis (chance of recovery) and treatment options. 

The prognosis (chance of recovery) and treatment options depend on the following: 

  • The stage of the cancer (whether it affects the inner lining of the rectum only, involves the whole rectum, or has spread to lymph nodes, nearby organs, or other places in the body). 
  • Whether the tumor has spread into or through the bowel wall. 
  • Where the cancer is found in the rectum. 
  • Whether all of the tumor can be removed by surgery. 
  • The patient’s general health. 
  • Whether the cancer has just been diagnosed or has recurred (come back). 

Stages of Rectal Cancer 


  • After rectal cancer has been diagnosed, tests are done to find out if cancer cells have spread within the rectum or to other parts of the body. 
  • There are three ways that cancer spreads in the body. 
  • Cancer may spread from where it began to other parts of the body. 
  • The following stages are used for rectal cancer: 
    • Stage 0 (Carcinoma in Situ) 
    • Stage I 
    • Stage II 
    • Stage III 
    • Stage IV 

After rectal cancer has been diagnosed, tests are done to find out if cancer cells have spread within the rectum or to other parts of the body. 

The process used to find out whether cancer has spread within the rectum or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. 

The following tests and procedures may be used in the staging process: 

Chest x-ray 

An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body. 


A procedure to look inside the rectum and colon for polyps (small pieces of bulging tissue). abnormal areas, or cancer. A colonoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer. 

CT scan (CAT scan) 

A procedure that makes a series of detailed pictures of areas inside the body, such as the abdomen, pelvis, or chest, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography. 

MRI (magnetic resonance imaging) 

A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI). 

PET scan (positron emission tomography scan) 

A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do. 

Endorectal ultrasound 

A procedure used to examine the rectum and nearby organs. An ultrasound transducer (probe) is inserted into the rectum and used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. The doctor can identify tumors by looking at the sonogram. This procedure is also called transrectal ultrasound. 

There are three ways that cancer spreads in the body. 

Cancer can spread through tissue, the lymph system, and the blood: 

  • Tissue. The cancer spreads from where it began by growing into nearby areas. 
  • Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body. 
  • Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body. 

Cancer may spread from where it began to other parts of the body. 

When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood. 

  • Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body. 
  • Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body. 

The metastatic tumor is the same type of cancer as the primary tumor. For example, if rectal cancer spreads to the lung, the cancer cells in the lung are actually rectal cancer cells. The disease is metastatic rectal cancer, not lung cancer. 

Many cancer deaths are caused when cancer moves from the original tumor and spreads to other tissues and organs. This is called metastatic cancer. This animation shows how cancer cells travel from the place in the body where they first formed to other parts of the body. 

Recurrent Rectal Cancer 

Recurrent rectal cancer is cancer that has recurred (come back) after it has been treated. The cancer may come back in the rectum or in other parts of the body, such as the colon, pelvis, liver, or lungs. 

Treatment Option Overview 


  • There are different types of treatment for patients with rectal cancer. 
  • Six types of standard treatment are used: 
    • Surgery 
    • Radiation therapy 
    • Chemotherapy 
    • Active surveillance 
    • Targeted therapy 
    • Immunotherapy 
  • Other types of treatment are being tested in clinical trials. 
  • Treatment for rectal cancer may cause side effects. 
  • Patients can enter clinical trials before, during, or after starting their cancer treatment. 
  • Follow-up tests may be needed. 

There are different types of treatment for patients with rectal cancer. 

Different types of treatment are available for patients with rectal cancer. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment. 

Six types of standard treatment are used: 


Surgery is the most common treatment for all stages of rectal cancer. The cancer is removed using one of the following types of surgery: 

  • Polypectomy: If the cancer is found in a polyp (a small piece of bulging tissue), the polyp is often removed during a colonoscopy. 
  • Local excision: If the cancer is found on the inside surface of the rectum and has not spread into the wall of the rectum, the cancer and a small amount of surrounding healthy tissue is removed. 
  • Resection: If the cancer has spread into the wall of the rectum, the section of the rectum with cancer and nearby healthy tissue is removed. Sometimes the tissue between the rectum and the abdominal wall is also removed. The lymph nodes near the rectum are removed and checked under a microscope for signs of cancer. 
  • Radiofrequency ablation: The use of a special probe with tiny electrodes that kill cancer cells. Sometimes the probe is inserted directly through the skin and only local anesthesia is needed. In other cases, the probe is inserted through an incision in the abdomen. This is done in the hospital with general anesthesia. 
  • Cryosurgery: A treatment that uses an instrument to freeze and destroy abnormal tissue. This type of treatment is also called cryotherapy. 
  • Pelvic exenteration: If the cancer has spread to other organs near the rectum, the lower colon, rectum, and bladder are removed. In women, the cervix, vagina, ovaries, and nearby lymph nodes may be removed. In men, the prostate may be removed. Artificial openings (stoma) are made for urine and stool to flow from the body to a collection bag. 

After the cancer is removed, the surgeon will either: 

  • Do an anastomosis (sew the healthy parts of the rectum together, sew the remaining rectum to the colon, or sew the colon to the anus) 
  • Make a stoma (an opening) from the rectum to the outside of the body for waste to pass through. This procedure is done if the cancer is too close to the anus and is called a colostomy. A bag is placed around the stoma to collect the waste. Sometimes the colostomy is needed only until the rectum has healed, and then it can be reversed. If the entire rectum is removed, however, the colostomy may be permanent. 

Radiation therapy and/or chemotherapy may be given before surgery to shrink the tumor, make it easier to remove the cancer, and help with bowel control after surgery. Treatment given before surgery is called neoadjuvant therapy.  

After all the cancer that can be seen at the time of the surgery is removed, some patients may be given radiation therapy and/or chemotherapy after surgery to kill any cancer cells that are left. Treatment given after the surgery, to lower the risk that the cancer will come back, is called adjuvant therapy. 

Radiation therapy 

Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy: 

  • External radiation therapy uses a machine outside the body to send radiation toward the cancer. 
  • Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. 

The way the radiation therapy is given depends on the type and stage of the cancer being treated. External radiation therapy is used to treat rectal cancer. 

Short-course preoperative radiation therapy is used in some types of rectal cancer. This treatment uses fewer and lower doses of radiation than standard treatment, followed by surgery several days after the last dose. 


Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping the cells from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy).  

When chemotherapy is placed directly in the cerebrospinal fluid, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). 

Chemoembolization of the hepatic artery is a type of regional chemotherapy that may be used to treat cancer that has spread to the liver. This is done by blocking the hepatic artery (the main artery that supplies blood to the liver) and injecting anticancer drugs between the blockage and the liver.  

The liver’s arteries then carry the drugs into the liver. Only a small amount of the drug reaches other parts of the body. The blockage may be temporary or permanent, depending on what is used to block the artery. The liver continues to receive some blood from the hepatic portal vein, which carries blood from the stomach and intestine. 

The way the chemotherapy is given depends on the type and stage of the cancer being treated. 

Active surveillance 

Active surveillance is closely following a patient’s condition without giving any treatment unless there are changes in test results. It is used to find early signs that the condition is getting worse. In active surveillance, patients are given certain exams and tests to check if the cancer is growing. When the cancer begins to grow, treatment is given to cure the cancer. Tests include the following: 

  • Digital rectal exam 
  • MRI (Magnetic Resonance Imaging) 
  • Endoscopy 
  • Sigmoidoscopy 
  • CT scan 
  • Carcinoembryonic antigen (CEA) assay 

Targeted therapy 

Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells without harming normal cells. 

Types of targeted therapies used in the treatment of rectal cancer include the following: 

Monoclonal antibodies 

Monoclonal antibody therapy is a type of targeted therapy being used for the treatment of rectal cancer. Monoclonal antibody therapy uses antibodies made in the laboratory from a single type of immune system cell. These antibodies can identify substances on cancer cells or normal substances that may help cancer cells grow. The antibodies attach to the substances and kill the cancer cells, block their growth, or keep them from spreading. Monoclonal antibodies are given by infusion. They may be used alone or to carry drugs, toxins, or radioactive material directly to cancer cells. 

There are different types of monoclonal antibody therapy: 

Vascular endothelial growth factor (VEGF) inhibitor therapy 

Cancer cells make a substance called VEGF, which causes new blood vessels to form (angiogenesis) and helps the cancer grow. VEGF inhibitors block VEGF and stop new blood vessels from forming. This may kill cancer cells because they need new blood vessels to grow. Bevacizumab and ramucirumab are VEGF inhibitors and angiogenesis inhibitors. 

Epidermal growth factor receptor (EGFR) inhibitor therapy 

EGFRs are proteins found on the surface of certain cells, including cancer cells. Epidermal growth factor attaches to the EGFR on the surface of the cell and causes the cells to grow and divide. EGFR inhibitors block the receptor and stop the epidermal growth factor from attaching to the cancer cell. This stops the cancer cell from growing and dividing. Cetuximab and panitumumab are EGFR inhibitors. 

Angiogenesis inhibitors 

Angiogenesis inhibitors stop the growth of new blood vessels that tumors need to grow. 

  • Ziv-aflibercept is a vascular endothelial growth factor trap that blocks an enzyme needed for the growth of new blood vessels in tumors. 
  • Regorafenib is used to treat colorectal cancer that has spread to other parts of the body and has not gotten better with other treatment. It blocks the action of certain proteins, including vascular endothelial growth factor. This may help keep cancer cells from growing and may kill them. It may also prevent the growth of new blood vessels that tumors need to grow. 


Immunotherapy is a treatment that uses the patient’s immune system to fight cancer. Substances made by the body or made in a laboratory are used to boost, direct, or restore the body’s natural defenses against cancer. This type of cancer treatment is also called biotherapy or biologic therapy. 

Immune checkpoint inhibitor therapy is a type of immunotherapy. 

Treatment Options by Stage 

Stage 0 (Carcinoma in Situ) 

Treatment of stage 0 may include the following: 

  • Simple polypectomy. 
  • Local excision. 
  • Resection (when the tumor is too large to remove by local excision). 

Stage I Rectal Cancer 

Treatment of stage I rectal cancer may include the following: 

  • Local excision. 
  • Resection. 
  • Resection with radiation therapy and chemotherapy after surgery. 

Stages II and III Rectal Cancer 

Treatment of stage II and stage III rectal cancer may include the following: 

  • Surgery. 
  • Chemotherapy combined with radiation therapy, followed by surgery. 
  • Short-course radiation therapy followed by surgery and chemotherapy. 
  • Resection followed by chemotherapy combined with radiation therapy. 
  • Chemotherapy combined with radiation therapy, followed by active surveillance. Surgery may be done if the cancer recurs (comes back). 
  • A clinical trial of a new treatment. 

Stage IV and Recurrent Rectal Cancer 

Treatment of stage IV and recurrent rectal cancer may include the following: 

  • Surgery with or without chemotherapy or radiation therapy. 
  • Systemic chemotherapy with or without targeted therapy (angiogenesis inhibitor). 
  • Systemic chemotherapy with or without immunotherapy (immune checkpoint inhibitor therapy). 
  • Chemotherapy to control the growth of the tumor. 
  • Radiation therapy, chemotherapy, or a combination of both, as palliative therapy to relieve symptoms and improve the quality of life. 
  • Placement of a stent to help keep the rectum open if it is partly blocked by the tumor, as palliative therapy to relieve symptoms and improve the quality of life. 
  • Immunotherapy. 
  • Clinical trials of chemotherapy and/or targeted therapy. 

Treatment of rectal cancer that has spread to other organs depends on where the cancer has spread. 

  • Treatment for areas of cancer that have spread to the liver includes the following: 
    • Surgery to remove the tumor. Chemotherapy may be given before surgery, to shrink the tumor. 
    • Cryosurgery or radiofrequency ablation. 
    • Chemoembolization and/or systemic chemotherapy. 
    • A clinical trial of chemoembolization combined with radiation therapy to the tumors in the liver. 

Source: National Cancer Institute