Guide to Rectal Cancer

Reviewed by the physicians of Columbia’s Colorectal Surgery Team, March 2024

What is Rectal Cancer?

Rectal cancer is cancer of the rectum: the last six inches of the digestive system that sits between the colon (large intestine) and the anus. It shares many similarities with colon cancer and the two cancers are commonly referred to as colorectal cancer. Most colorectal cancers begin as a polyp – a growth of tissue on the lining of the colon or rectum. Not all polyps are dangerous, but the type known as an adenoma may become cancerous unless removed. Colorectal cancers usually develop slowly over many years and are treatable if diagnosed early through regular screening.

Risk Factors

You may be at increased risk if:

  • You or a close relative have had colon polyps or colon cancer
  • You have a history of inflammatory bowel disease (Crohn's Disease or Ulcerative Colitis)
  • You have certain genetic syndromes, like familial adenomatous polyposis (FAP) or hereditary non-polyposis colon cancer (also known as Lynch syndrome)


Don’t wait for symptoms to develop as rectal cancers often do not produce any symptoms until late in the disease. Symptoms include changes in bowel habits for more than a few days; feeling the need to have a bowel movement even after having just had one, rectal bleeding, cramping or abdominal pain, weakness and fatigue, and unexpected weight loss.


The best way to prevent rectal cancer is examining the large intestine by colonoscopy. The death rate from colon and rectal cancers has been declining over the past two decades because of the increase in prevalence of screening and early prevention. The American Cancer Society recommends that people at average risk for colorectal cancer have a screening test (colonoscopy or other type) beginning at age 45. The five-year survival rate for colorectal cancer now stands at about 90 percent when the cancer is found and treated early. Men and women with certain colon or rectal cancer risk factors should speak with their doctors about starting screening at a younger age and possibly being screened more often than people at average risk.


Colorectal cancer screening is important because most patients with early stage cancer do not have any symptoms. Patients with colorectal cancers surgically removed at an early stage have a greater chance of being cured than those whose cancers are detected at a later stage.

All men and women over the age of 45 should be screened for colorectal cancer regardless of family or personal risk factors. A number of tests are available to screen for cancer.

The following may be used alone or in combination with each other: 

  • Fecal Occult Blood Test (FOBT) – This test checks for occult (hidden) blood in the stool.
  • Flexible Sigmoidoscopy – This test examines the inside of the rectum and lower portion of the colon through a flexible, lighted tube. The doctor may remove polyps and collect samples of tissue or cells for closer examination.
  • Colonoscopy – Colonoscopy is used to detect precancerous colon polyps before they become cancerous. In this examination, a doctor looks at the inside of the rectum and entire colon through a flexible, lighted tube. The doctor may remove polyps and collect samples of tissue or cells for closer examination.
  • Double Contrast Barium Enema – The patient is given an enema containing a dye (barium), followed by an injection of air. X-rays of the rectum and colon are then taken. The barium outlines the intestine on the x-ray film, so that polyps and other abnormalities may be easily seen.
  • Virtual Colonoscopy (CT Colonography) – This test involves performing a special CT Scan (or CAT Scan) which specifically examines the colon and rectum for polyps and tumors. Just like a traditional colonoscopy, this test requires that you cleanse the colon the day prior with a bowel preparation solution (taken orally).


Colorectal cancer is often diagnosed with colonoscopy. As addressed earlier, nearly all cases of colorectal cancer begin with the growth of polyps. During a colonoscopy, your doctor examines the inside of the rectum and entire colon through a flexible, lighted tube. Confirmation of the diagnosis can only be made by taking a sample (biopsy) of the potentially cancerous tissue for examination by a pathologist. 


The primary treatment for both rectal and colon cancer is surgery. In rectal cancer, radiation and chemotherapy are often given before surgery to shrink the tumor before its removal. Depending on the stage and location of the tumor, different surgical methods may be used. For cancers in the lower area of the rectum, surgical instruments may be inserted through the anus. For those higher up, an abdominal incision may be required.

For advanced cases, the entire rectum might need to be removed (known as a proctectomy). This could result in the need for a temporary or permanent colostomy – an external waste bag for fecal matter.

FAQ’s for Colon and Rectal Surgery

Once it has been determined that I have a growth in my colon or rectum, will I need additional diagnostic studies?

If your problem was diagnosed using a digital rectal exam, or through fecal occult blood testing (Hemoccult® test), you will need additional evaluation, most likely by colonoscopy, which examines the entire colon and rectum, or, at least, by sigmoidoscopy, which examines the final two feet of the colon and the rectum. These examinations are important not only to determine the extent of the current problem, but also to look for other abnormalities, which might also be present and could influence your best course of treatment. Your physician will determine which test is best for you.

Prior to having surgery on my colon or rectum, will I need any additional preoperative evaluation?

A variety of laboratory examinations, including chest X-ray, EKG, CBC (complete blood count), chemistries, coagulation parameters, are routinely required. If you are anemic or there is risk for significant blood loss, a sample of your blood will be held at the blood bank to expedite replacement blood in your type if transfusion becomes necessary. A CT or CAT scan of the abdomen and pelvis may be ordered by your physician. This study can help to evaluate the local or metastatic (spread) of any cancer. For rectal cancers, a transrectal ultrasound, which determines the depth of a tumor and possible lymph node involvement, can also help in determining the best treatment options. Other special studies may be dictate by your general state of health. For example, if you have emphysema, a pulmonologist may be consulted and perform pulmonary function tests or an arterial blood gas. Your surgeon will evaluate the necessity of such studies.

Prior to my sigmoidoscopy or colonoscopy, or colorectal surgery, will I require any special bowel preparation?

So that the lining of the colon can well-visualized during colonoscopy, it is necessary to remove the stool using laxatives taken by mouth. Popular choices include GoLytely®, Nulytely®, Fleet® Phosphosoda, and Magnesium Citrate. Preparation for sigmoidoscopy, a test that views only the lower portion of the colon, is routinely done with enemas (often, Fleet® enemas). Your physician will choose a regimen which will allow the most comfort while appropriately cleansing your colon. Preparation for an abdominal colon resection or rectal excision requires that your colon be cleansed of stool and bacteria. This cleansing allows for a safer anastomosis (joining of two pieces of bowel), and decreases the incidence of wound infection. Your physician will choose the appropriate regimen for you, which may include oral antibiotics such as erythromycin, neomycin, or ciprofloxacin. It is very important that, whichever plan is established, you follow the prescription completely. If you are unable to complete the plan, your surgery may need to be cancelled or rescheduled. Please call your physician's office with any problems.

What is a stoma, and will I need a one?

A stoma, commonly referred to as a colostomy or ileostomy, is an artificial opening in the abdomen created during surgery that allows elimination of stool after the operation. It is necessary if passage to the anus is interrupted after the operation. The colostomy may be temporary, to give the colon a chance to heal, or permanent (in 10 to 15 percent of cases) if the lower part of the rectum has been removed. In most cases, if a stoma will be permanent, your surgeon will be able to tell you this prior to the procedure. However, if your anastomosis (rejoining of the bowel) is low, or there are other factors encountered during the operation that cause your surgeon to be concerned about your safety, a temporary stoma may be required. This "protecting" or "diverting" stoma may be in the form of a colostomy or ileostomy brought to the skin's surface before the anastomosis, thus allowing time for healing without being bathed by stool and bacteria. The stoma may be closed or reconnected at a later date, after healing of your anastomosis has taken place. This healing is confirmed by a radiologic study, such as a gastrograffin enema, and/or by direct visualization, which will view the lining and may offer an opportunity to dilate a narrowed ("strictured") area. Caring for a stoma is enhanced by specially-trained nurses called "enterostomal" therapists. They help teach you about stoma care, skin care, and appliance management. They can also introduce you to other patients with stomas ("stomates") so that you can learn from their experiences.

How will my pain be managed after the surgery?

In the immediate postoperative period, you will receive some form of analgesia which you can control, termed Patient Controlled Anesthesia ("PCA"). This may be a device with a button you push to deliver intravenous medication to yourself, or in the form of an epidural catheter, with the same opportunity to self-administer additional pain medication. The epidural catheter is similar to that placed in women who are in labor and is very safe. It seems to block the input of pain sensation, and therefore, if effective, will block the response to pain. Once you are able to take pain medicine by mouth, these other methods will be removed. Interim forms of pain management include intravenous or intramuscular injections given by the nursing staff.

How long will I need to stay in the hospital after my surgery?

The length of hospital stay varies depending on the individual and the type of surgery. In general, the length of stay ranges from 4 to 10 days. Most surgeons will keep their patients in the hospital until they can take food and pain medicine by mouth, are urinating, and having bowel movements. Individual practices may vary, so this issue should be discussed with your surgeon prior to your surgery. Special needs or concerns (for example, in the elderly who require assisted living) may require that special arrangements be made prior to the surgery. These concerns should be discussed with your physician, family and friends well in advance so that proper arrangements can be made.

How will the diagnosis of colon or rectal cancer affect my family?

It is common that a diagnosis of cancer may both frighten and upset your family. However, there are now several therapeutic options available to patients, and these should be discussed at length with your surgeon and with your family prior to making final decisions. Letting your family know will give them time to adjust, and help you make decisions in a time when your own decision-making processes may be more difficult. Additionally, if it appears that you have a family history of colon, ovarian, endometrial, gastric, or pancreatic cancer, it is important for your family members to be screened as well. Colon cancer, as mentioned above, may be preventable in its early stages.

Preparing for your First Appointment

If you have recently had any imaging studies performed, such as an MRI or CT scan, it is very important to bring a copy of the study as well as the imaging report. The findings of your imaging study will help your physician decide if you need a procedure and if so, what kind. If you have had the imaging study performed at NewYork-Presbyterian Hospital/Columbia University Medical Center, we will be able to access the reports internally. However, if your imaging study was performed at an outside facility, we strongly encourage you to obtain a copy of the images and accompanying report ahead of time to bring with you to your consultation. If you do not have these items with you, we may have to request them directly from the facility that performed the study. That extra step can delay your diagnosis and treatment.

Before your first appointment, please download and print the following two forms, fill them out, and bring them with you to your appointment.

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