Rectal cancer is cancer that develops in cells in the rectum, which is below the sigmoid colon and above the anus.

Your rectum and colon are both part of the digestive system, so rectal and colon cancers are often grouped under the term colorectal cancer.

In the United States, colorectal cancer is the third most common type of cancer. It’s also the second deadliest, making early detection and treatment critical. Worldwide, colorectal cancer is the second most common cancer in females and the third most common cancer in males, according to a 2020 data from Worldwide Cancer Research Fund.

The American Cancer Society estimates there will be 44,850 new cases of rectal cancer in the United States in 2022. This compares with 106,180 new cases of colon cancer.

At first, rectal cancer may be asymptomatic.

As the cancer progresses, rectal bleeding is the most common symptom. Changes in your bowel habits may occur, lasting for more than a few days. You may also experience unexplained weakness and fatigue.

According to the Centers for Disease Control and Prevention (CDC), common symptoms of colorectal cancer may include:

  • rectal bleeding
  • changes in how often you have bowel movements
  • feeling that your bowel isn’t emptying completely
  • pain when you have a bowel movement
  • diarrhea or constipation
  • blood or mucus in your stool
  • unintentional weight loss and appetite changes
  • unexplained fatigue
  • frequent abdominal discomfort, gas, cramps, pain

Another possible sign of rectal cancer is iron-deficiency anemia, which may occur as a result of blood loss.

While the exact cause of rectal cancer is unknown, malignant tumors develop when cancerous cells grow out of control and multiply. These cells can penetrate and destroy healthy tissue. What sets off this process isn’t always clear.

There are some inherited gene mutations that can increase your risk for rectal cancer. One of these is hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome. This disorder significantly raises the risk of colon and other cancers. In some cases, your doctor may recommend removing your colon as a preventive measure.

Another genetic condition that may cause rectal cancer is familial adenomatous polyposis (FAP). This is a rare disorder that can cause polyps to grow in the lining of the colon and rectum.

While these polyps start off as noncancerous, they may become malignant. In fact, most people with FAP develop cancer before the age of 50. Large bowel removal may also be a preventive surgery your doctor may recommend.

Like other types of cancers, rectal cancer can spread when cancerous cells grow in healthy tissue and travel to other areas of the body.

At first, rectal cancer may affect the tissues lining the rectum. In some cases, it affects the entire rectum. The cancer may then spread to nearby lymph nodes or organs, with the liver being commonly affected. Other possible areas of metastasis can include the:

  • abdomen
  • brain
  • lungs
  • ovaries

While there’s no single known cause of rectal cancer, a number of known factors may increase your risk for developing this cancer at some point. These include the following:

  • Age. Diagnosis usually occurs after age 50, although rates are increasing among younger people.
  • Race. Black Americans are at higher risk than other groups of developing rectal cancer. One reason for this may be inequities in healthcare access.
  • Family history. Personal or family history of colorectal cancer can raise risk.
  • Genetics. Lynch syndrome or FAP are two genetic conditions that may increase your risk.
  • Radiation therapy. Previous radiation treatment to the abdomen can increase risk.

Other conditions that may increase risk include:

Some lifestyle factors that may play a role in colorectal cancer are:

  • eating a diet low in vegetables and fiber
  • eatinga diet high in red and processed meat
  • a lack of exercise
  • smoking
  • consuming three or more alcoholic drinks per day

Rectal cancer is diagnosed with a combination of the following:

Physical exam and screening tests

The doctor will likely begin by taking your medical history and performing a physical exam. This may include inserting a gloved finger into your rectum to feel for lumps.

The doctor might next recommend a fecal immunochemical test (FIT) or a sigmoidoscopy. The screening schedule for these tests will vary depending on your risk level. If these tests are positive for cancer, a colonoscopy is the next step.


In a colonoscopy, a doctor uses a thin tube with a light and camera at the end to view the inside of your rectum and colon. They can usually remove any polyps they find at this time.

During the colonoscopy, the doctor can also collect tissue samples for later examination in a lab. These samples can be viewed under a microscope to determine if they’re cancerous. They can also be tested for genetic mutations associated with colorectal cancer.

Blood tests

The doctor may also order a blood test. A high level of carcinoembryonic antigen (CEA), a substance made by cancerous tumors, in your bloodstream may indicate rectal cancer.

Imaging tests

Once the doctor makes their diagnosis of rectal cancer, their next step is to determine how far it might have spread.

The doctor may use an endorectal ultrasound to examine your rectum and surrounding area. For this test, a doctor inserts a probe into your rectum to produce a sonogram, a type of image.

The doctor may use other imaging tests to look for signs of cancer throughout your body. These include:

No matter where it starts, cancer can spread, or metastasize, through tissue, the lymphatic system, or the bloodstream to reach other parts of the body.

Staging cancer indicates how far the cancer has progressed, which can help doctors decide the best treatment.

Below are the stages of rectal cancer.

Stage 0 (carcinoma in situ)

Only the innermost layer of the rectum wall contains abnormal cells.

Stage 1

Cancer cells have spread past the innermost layer of the rectum wall but not to lymph nodes.

Stage 2

Cancer cells have spread into or through the outer muscle layer of the rectum wall but not to lymph nodes. This is often referred to as stage 2A. In stage 2B, the cancer has spread into the abdominal lining.

Stage 3

Cancer cells have spread through the outermost muscle layer of the rectum and to one or more lymph nodes. Stage 3 is often broken up into substages 3A, 3B, and 3C based on the amount of lymph node tissue affected.

Stage 4

Cancer cells have spread to distant sites, like the liver or lungs.

In recommending treatment, the doctor and care team will consider:

  • tumor size
  • where cancer may have spread
  • your age
  • your general health

This can help them determine the best combination of treatments, as well as the timing of each treatment.

Below are the general guidelines for treatment by stage. This list contains potential treatment options. Not all patients may require the treatment options listed for each stage.

Stage 0

  • removal of suspicious tissue during colonoscopy
  • removal of tissue during a separate surgery
  • removal of tissue and part of the surrounding area

Stage 1

  • local excision or resection
  • radiation therapy for some patients
  • chemotherapy for some patients

Stages 2 and 3

  • surgery
  • radiation therapy
  • chemotherapy

Stage 4

  • surgery, possibly in more than one area of the body
  • radiation therapy
  • chemotherapy
  • targeted therapies, such as monoclonal antibodies or angiogenesis inhibitors
  • cryosurgery, a procedure that uses a cold liquid or a cryoprobe to destroy abnormal tissue
  • radiofrequency ablation, a procedure in which radio waves are used to destroy abnormal cells
  • a stent to keep the rectum open if it’s blocked by a tumor
  • palliative therapy to improve overall quality of life

You can also ask your doctor about clinical trials that might be a good fit. Many current therapies for cancer began as clinical trials. These trials may try different combinations of current treatment, treatments that have been approved by the U.S. Food and Drug Administration (FDA) for other conditions, or new treatments.

In some cases, therapy as part of a clinical trial may be covered by insurance or covered by a sponsor of the trial.

Clinical trials can help advance scientists’ understanding of cancer and investigate new treatment options. Participating may offer additional options for your treatment. You can learn more about clinical trials for rectal cancer at the National Cancer Institute.

Rectal cancer may spread outside of the rectum, eventually affecting surrounding tissues, lymph nodes, and organs.

You may also be at risk of developing second cancers, which occur after treatment of the initial cancer. Rectal cancer may especially increase the risk of secondary cancers affecting the:

  • anus
  • colon
  • kidneys
  • lungs
  • small intestine
  • vagina

A diagnosis of colorectal cancer in the early stages, before it spreads, can improve your chances of survival.

According to the CDC and the American Cancer Society, the best way to reduce your overall risk for developing colorectal cancer is to begin regular screenings beginning at age 45. Depending on family history, genetics, and other risk factors, your doctor may recommend screenings sooner than this.

Colon and rectal cancer can be diagnosed early when discovered through routine screenings, such as a routine colonoscopy or stool test. Highly sensitive stool tests can detect the presence of cancer. If abnormal cells are discovered, a timely colonoscopy should also be performed.

You may also be able to help prevent rectal cancer by adopting a healthy lifestyle and eliminating related risk factors such as inactivity, smoking, and eating red or processed meats.

Advances in treatment over the last few decades have improved the overall outlook for people with rectal cancer. In fact, many cases of rectal cancer can be treated successfully.

It’s also important to consider the 5-year survival rate, which is determined based on the average number of people who are alive after 5 years or being diagnosed with a certain type of cancer and its stage. The overall 5-year survival rate for rectal cancer is 67 percent for all stages combined.

The 5-year relative survival rate by stage is:

  • Localized: 89 percent
  • Regional: 72 percent
  • Distant: 16 percent

It’s important to note that these figures are based on information between 2010 and 2016. Since then, treatments may have been modified and improved. These numbers may not reflect current survival rates.

For people with rectal cancer, your outlook can depend on other factors that can include:

  • where cancer may have spread
  • whether your bowel is blocked
  • if the entire tumor can be surgically removed
  • age and general health
  • whether this is a recurrence
  • how well you tolerate treatment

When it comes to your individual outlook, the best source of information is your own doctor.

Rectal cancer, commonly referred to as colorectal cancer, is common in both the United States and worldwide. The symptoms of rectal cancer may not appear until the later stages, which makes early, regular screenings an important factor in both detection and treatment.

Treatment and screening options may continue to evolve, but it’s also important to reduce your own risk if you can. Talk with your doctor about any personal concerns you have about rectal cancer risks, and whether you’re experiencing any unusual bowel-related symptoms.