Rectal Cancer

Rectal cancer is a type of cancer that develops in the last several inches of the large intestine, known as the rectum. While it shares similarities with colon cancer, rectal cancer requires different treatment approaches due to the rectum’s location deep within the pelvis, close to other vital organs.

Table of contents

• What is rectal cancer?
• Where the rectum is located
• Who is at risk for rectal cancer?
• Signs and symptoms
• How rectal cancer is diagnosed
• Treatment options
• Prevention and screening
• Living with rectal cancer

What is rectal cancer?

Rectal cancer is a disease in which cells in the rectum grow out of control and form a tumor, which is an abnormal mass of tissue^[1]. This type of cancer typically grows slowly, developing from small clumps of abnormal cells called polyps, specifically adenomas^[2]. It can take anywhere from 10 to 15 years for a polyp to turn into a cancerous tumor^[2].

Rectal cancer is the second most common cancer in the large intestine and the third most common cancer in the digestive system, following colon cancer and pancreatic cancer^[2][5]. Experts estimate that 46,200 people will receive a rectal cancer diagnosis in 2024^[2].

Where the rectum is located

The rectum is part of the body’s digestive system. The digestive system takes in nutrients from foods and helps pass waste material out of the body^[3]. It is made up of the esophagus, stomach, and the small and large intestines.

The rectum is the last several inches of the large intestine, typically measuring between 6 and 8 inches long^[1][3]. It starts at the end of the colon, which is about 5 feet long and makes up most of the large intestine. Together, the rectum and a short, narrow passage called the anal canal form the last part of the large intestine. The anal canal ends at the anus, which is the opening of the large intestine to the outside of the body^[3].

The location of the rectum within the tight space of the pelvic cavity, close to other organs and structures, makes surgery to remove rectal cancer more complex than surgery for colon cancer. This is why rectal and colon cancers, while similar in many ways, are treated quite differently^[1].

Who is at risk for rectal cancer?

The exact cause of rectal cancer is unknown. However, colorectal cancer is caused by certain changes to the way colorectal cells function, especially how they grow and divide into new cells^[3]. There are many risk factors that increase the chance of developing rectal cancer, but many do not directly cause cancer. Instead, they increase the chance of DNA damage in cells that may lead to colorectal cancer^[3].

Risk factors for rectal cancer include^[2][3][4]:

• Age: Older age is a main risk factor for most cancers. The chance of getting cancer increases as you get older. The average age of diagnosis for rectal cancer is 63^[2].
• Family history: Having a first-degree relative, such as a parent, sibling, or child, with a history of colon or rectal cancer almost doubles your risk^[2][3].
• Personal history of cancer: Having a personal history of colon, rectal, or ovarian cancer increases your risk^[3].
• Polyps: Having a personal history of high-risk adenomas, which are colorectal polyps that are 1 centimeter or larger in size or have cells that look abnormal under a microscope^[3].
• Inherited genetic conditions: Having inherited changes in certain genes that increase the risk of familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary nonpolyposis colorectal cancer), as well as other inherited colorectal cancer syndromes including MUTYH-associated polyposis, juvenile polyposis syndrome, Peutz-Jeghers syndrome, and PTEN hamartoma tumor syndrome^[2][3].
• Inflammatory bowel diseases: Having a personal history of chronic ulcerative colitis or Crohn disease, which are inflammatory bowel diseases, for 8 years or more^[2][3].
• Diet: People who eat a lot of red meat and processed meat have a higher risk of developing rectal cancer^[2].
• Alcohol: Having three or more alcoholic drinks per day^[3][4].
• Smoking: Smoking cigarettes increases the risk^[2][3].
• Obesity: People who have obesity are more likely to have rectal cancer compared to people who don’t^[2][3].
• Race: People who are Black are statistically more likely to develop rectal cancer, though the reasons for this aren’t fully understood yet^[2][3].
• Sex: Men are slightly more likely to develop rectal cancer than women^[2].

Having one or more of these risk factors does not mean that you will definitely get colorectal cancer. Many people with risk factors never develop colorectal cancer, while others with no known risk factors do. It’s important to talk with your doctor if you think you might be at increased risk^[3].

Signs and symptoms

Rectal cancer may not cause symptoms early on. You can have rectal cancer for years without noticing changes in your body. In many cases, rectal cancers don’t cause symptoms at all^[1][2]. When symptoms do appear, they usually happen when the disease is more advanced^[1].

Common symptoms of rectal cancer may include^[1][2][3][4]:

• Blood in the stool, which may make stool look dark maroon or bright red in color, or rectal bleeding
• A change in bowel habits, such as diarrhea, constipation, or a more frequent need to pass stool
• A feeling that the bowel doesn’t empty completely
• Narrow stool, or stools that are stringy or as thin as a pencil
• Abdominal pain or general abdominal discomfort, such as frequent gas pains, bloating, fullness, or cramps
• Weight loss that happens without trying, or unexplained weight loss
• Weakness or fatigue, or feeling very tired
• A change in appetite
• A lump in the rectum, which may be found during a medical exam

These symptoms may be caused by rectal cancer or by other conditions. Many of these symptoms can also be caused by common health problems such as hemorrhoids. It’s important to check with your doctor if you have any of these signs and symptoms^[3][4].

How rectal cancer is diagnosed

Rectal cancer can be found during a screening test for colorectal cancer, or it may be suspected based on your symptoms^[10]. Diagnosis begins with routine screening tests and is followed by additional tests to confirm the diagnosis and determine the extent of the cancer.

Tests used to diagnose rectal cancer include^[2][4][10]:

• Digital rectal exam (DRE): A 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^[3][4].
• Colonoscopy: A test to look at the colon and rectum using a long, flexible tube with a camera at the end, called a colonoscope. Your healthcare professional looks for signs of cancer. Medicines are given before and during the procedure to keep you comfortable^[10].
• Biopsy: During a colonoscopy, a healthcare professional may pass special cutting tools through the colonoscope to remove a very small sample of tissue from inside the rectum. The tissue sample is sent to a lab to look for cancer cells. Other special tests give more details about the cancer cells^[10].
• Sigmoidoscopy or proctoscopy: An office-based procedure where a scope is used to look into the rectum, with or without a camera^[6].

If you’re diagnosed with rectal cancer, the next step is to determine the cancer’s extent, called the stage^[10]. Your healthcare team uses the cancer staging test results to help create your treatment plan.

Staging tests may include^[2][6][10]:

• Blood tests: Including a complete blood count (CBC) to check for anemia and blood loss, and a CEA (Carcinoembryonic Antigen) test, which looks for a certain protein excreted by some colon and rectal cancers^[6].
• CT scans: Imaging tests that help determine if the cancer has spread to other locations within the body.
• MRI scans: Imaging that helps determine how much the tumor has spread in the area near the tumor and local lymph nodes^[6].
• Endorectal ultrasound: A test that helps determine how much the tumor has spread locally^[6].
• PET scans: Imaging that helps determine if the cancer has spread to other locations^[6].

The stage of the cancer is generally the most important factor in determining outcomes. Other factors that can affect outcomes include the location of the tumor in the rectum, whether the tumor is causing blockage of the bowel or a hole in the rectum, as well as the patient’s general health and ability to tolerate treatment^[6].

Treatment options

Treatment for rectal cancer depends on the stage of the cancer, the location of the tumor in the rectum, and the patient’s general health^[1][6]. The main treatments include surgery, chemotherapy, radiation therapy, and combinations of these approaches.

Surgery is a common treatment to remove the cancer. Rectal cancer treatment often involves surgery to remove the cancer^[1]. If you have rectal cancer, surgery to remove small cancerous tumors may cure the condition^[2]. The type of surgery depends on the position and stage of the cancer^[12]. If the tumor was small and had not spread, a doctor may have removed it during the colonoscopy^[22].

Chemotherapy uses medicines that destroy cancer cells. You might have chemotherapy on its own or with radiotherapy^[12]. Drugs used for rectal cancer include fluorouracil, capecitabine, oxaliplatin, and irinotecan^[12].

Radiation therapy uses high energy waves similar to x-rays to kill cancer cells. Radiotherapy uses high energy waves to kill bowel cancer cells and is a treatment for cancer of the back passage^[12].

Chemoradiotherapy combines chemotherapy and radiotherapy. Treatment with chemotherapy and radiotherapy together is called chemoradiotherapy. You might have this treatment for cancer of the back passage^[12].

Other treatments may include targeted therapy and immunotherapy^[1]. Treatment may be given before surgery (called neoadjuvant treatment) or after surgery (called adjuvant treatment) to help prevent the cancer from coming back.

Some people with rectal cancer may be candidates for a “watch-and-wait” approach after treatment with chemotherapy and radiation, if the tumor responds completely to the initial treatment^[21].

Prevention and screening

Most colon and rectal cancers start as polyps. Rectal cancers can be prevented by discovering and removing these polyps with colonoscopy^[6]. It usually takes years for a polyp to become a cancer, so routine detection and removal of these polyps will greatly decrease the development of colon and rectal cancers^[6].

Regular screenings to detect and remove polyps reduce your risk of developing rectal cancer^[2]. All patients should discuss recommendations for colon and rectal cancer screening with their health care providers. Screening for the average risk patient should begin at age 45^[6][7]. This may be different for individuals depending on personal and family health history^[6].

Screening methods include^[6]:

• Colonoscopy, which is used to both detect and remove colon and rectal polyps, and to diagnose and evaluate cancers
• FIT testing, which detects traces of blood in the stool
• Tests that look for abnormal DNA in the stool

Evidence also suggests that a high fiber, low fat diet may decrease the risk of developing colon or rectal cancer^[6].

Living with rectal cancer

Getting practical and emotional support can help you cope with a diagnosis of rectal cancer. It can also help you with life during and after treatment^[19].

After treatment, you have regular check ups and tests at the hospital. The doctors check how you are and see whether you have any problems or worries^[12]. Follow-up care is a key part of your treatment and safety^[22].

Treatment for rectal cancer can cause changes to your bowel. These effects can last for a few weeks or months after treatment, and sometimes they might go on for longer^[19]. You might need to look at what you eat and make changes to your diet after treatment. You may need to experiment a bit to find out which foods upset your system. A dietitian can support you with diet problems from diagnosis, through treatment and afterwards^[19].

If you have difficulty controlling your bowel movements or experience diarrhea, it’s important to drink plenty of fluids to prevent dehydration. When you are able to eat, try clear soups, mild foods, and liquids. Other good choices include dry toast, crackers, cooked cereal, and gelatin dessert^[22].

Some people may have a colostomy or ileostomy after surgery for bowel cancer. The end of your bowel is brought out into an opening on your tummy, called a stoma or ostomy^[19].

Many people find it helpful to join a support group. Speaking with people who are in the same situation can help you find new ways to cope with your condition^[16]. Support groups can be helpful even for people who have a good support network already.

It’s important to take steps to manage stress, such as learning relaxation techniques. To also help reduce stress, get enough sleep, eat a healthy diet, and take time to do things you enjoy^[22]. Don’t forget that there’s still life between treatments. Get out and do things that you love and visit with family members you haven’t seen in a while^[16].

Palliative care is specialized medical care for people living with serious illnesses, like colorectal cancer. This type of care focuses on relief from the symptoms and stress of a serious illness. The goal is to improve quality of life for both the patient and the family^[20]. The main organization representing cancer doctors, the American Society of Clinical Oncology, recommends that you should receive palliative care early in the disease and along with treatment for the cancer itself^[20].