In short

Rectal neoplasm, commonly known as rectal cancer, is a disease where abnormal cells grow in the tissues of the rectum, the last several inches of the large intestine. While it typically develops slowly over many years, early detection through screening can catch growths before they become cancerous, and surgery may cure the disease when found early.

What is rectal neoplasm?

Rectal neoplasm, more commonly called rectal cancer, is a disease in which malignant cells (cancer cells) form in the tissues of the rectum. The term "neoplasm" means abnormal growth of tissue. Rectal cancer typically is a slow-growing cancer that forms on the inner lining of the rectum.

Most rectal cancers start as clumps of abnormal cells called polyps, specifically known as adenomas. It can take 10 to 15 years for a polyp to turn into a cancerous tumor on the rectum. This long development period means that cancer screening, such as colonoscopies, can often detect polyps before they become cancer. Regular screenings to detect and remove polyps significantly reduce your risk of developing rectal cancer.

Rectal cancer is the third most common cancer in the digestive system, behind colon cancer and pancreatic cancer. Experts estimate 46,200 people will receive a rectal cancer diagnosis in 2024. Colon and rectal cancers combined are the fourth most common form of cancer in the United States, with an estimated 151,030 newly diagnosed cases in 2022.

Understanding the rectum

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. 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. It starts at the end of the final segment of the colon and ends when it reaches the short, narrow passage known as the anus. The colon (large bowel) is the main 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 to 8 inches long. The anal canal ends at the anus, which is the opening of the large intestine to the outside of the body.

By rigid sigmoidoscopy, the rectum measures between 10 cm and 15 cm from the anal verge. The rectum is located within the pelvis. The bony constraints of the pelvis limit surgical access to the rectum, which results in a lower likelihood of attaining widely negative margins and a higher risk of local recurrence compared to colon cancer.

Rectum
Large intestine
Anus

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. Symptoms of rectal cancer usually happen when the disease is advanced.

When symptoms are present, they are often mistaken for other problems such as hemorrhoids. These symptoms may be caused by rectal cancer or by other conditions. If you experience any of the following signs, you should check with your doctor:

Rectal bleeding, which may make stool look dark maroon or bright red in color
Blood in or on your stool
A change in bowel habits, such as diarrhea, constipation or a more frequent need to pass stool
Feeling that the bowel doesn't empty completely
Narrow stool or stools that are more narrow than usual
Poop that looks stringy or as thin as a pencil
Abdominal pain or discomfort
Weight loss that happens without trying
Weakness or fatigue
A lump in the rectum

With the exception of obstructive symptoms, these symptoms do not necessarily correlate with the stage of disease or signify a particular diagnosis.

Risk factors

The exact cause of rectal cancer is unknown. However, there are certain risk factors that increase your chance of developing the disease. A risk factor is anything that increases the chance of getting a disease. Some risk factors, like smoking, can be changed. However, risk factors also include things you cannot change, like your genetics, getting older, and your family history.

Having one or more risk factors does not mean that you will get colorectal cancer. Many people with risk factors never develop colorectal cancer, while others with no known risk factors do.

Age

Older age is a main risk factor for most cancers. The chance of getting cancer increases as you get older. Like most cancers, the risk of rectal cancer increases with age. The average age of diagnosis is 63. However, there has been a noticeable trend towards earlier age at diagnosis, and the recommended age when screening should start was recently lowered to 45.

Family history

If you have a biological family member who has been diagnosed with rectal cancer, your chance of developing it is almost double. Having a first-degree relative (parent, sibling, or child) with a history of colon or rectal cancer increases your risk.

Personal medical history

Several health conditions and personal medical history factors can increase your risk:

Having a personal history of colon, rectal, or ovarian cancer
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)
Inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis, especially having chronic ulcerative colitis or Crohn disease for 8 years or more

Inherited conditions

Inherited conditions that increase rectal cancer risk include:

Lynch syndrome (hereditary nonpolyposis colorectal cancer)
Familial adenomatous polyposis (FAP)
MUTYH-associated polyposis (MAP)
Juvenile polyposis syndrome (JPS)
Peutz-Jeghers syndrome
PTEN hamartoma tumor syndrome

Lifestyle factors

Several lifestyle factors can increase your risk of developing rectal cancer:

Eating processed meat: People who eat a lot of red meat and processed meat have a higher risk
Having three or more alcoholic drinks per day
Smoking cigarettes. Recent research suggests that people who smoke tobacco are more likely to die from rectal cancer than people who don't
Obesity: People who have obesity are more likely to have rectal cancer compared to people who don't have obesity

Other factors

Sex: Men are slightly more likely to develop rectal cancer than women
Race: Statistically, people who are Black are more likely to develop rectal cancer. The reasons for this aren't fully understood yet

How rectal cancer is diagnosed

Rectal cancer diagnosis often begins with an imaging test to look at the rectum. Rectal cancer can be found during a screening test for colorectal cancer, or it may be suspected based on your symptoms.

Physical examination

A careful history and physical examination, including a digital rectal exam (DRE), are paramount on clinical suspicion. During a DRE, 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.

Endoscopic procedures

An endoscopy examination with rigid sigmoidoscopy is required to measure the distance from the lesion to the anal verge (less than 15 cm) and for tissue biopsy for pathological confirmation of rectal cancer.

Colonoscopy is a test to look at the colon and rectum. It uses a long, flexible tube with a camera at the end, called a colonoscope, to show the colon and rectum. Your healthcare professional looks for signs of cancer. Medicines are given before and during the procedure to keep you comfortable. Colonoscopy is used to both detect and remove colon and rectal polyps, and to diagnose and evaluate cancers of the colon and rectum.

Biopsy

A biopsy is a procedure to remove a sample of tissue for testing in a lab. To get the tissue sample, a healthcare professional passes special cutting tools through a colonoscope and uses the tools 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.

Imaging tests

After rectal cancer has been diagnosed, imaging tests are done to find out if cancer cells have spread within the rectum or to other parts of the body. Once rectal cancer has been established pathologically, an MRI or transrectal ultrasound can accurately determine local tumor extension and node status. Baseline computed tomography (CT scans) of the chest, abdomen, and pelvis can help determine if the cancer has spread to other locations within the body.

Blood tests

Your oncologist may order blood tests to look for signs of rectal cancer. A complete blood count (CBC) reports the numbers of different types of cells in the blood and can show the risk of certain conditions. Blood tests can include a CEA (Carcinoembryonic Antigen) test, which looks for a certain protein excreted by some colon and rectal cancers.

Treatment options

Rectal cancer treatment often involves surgery to remove the cancer. Other treatments may include chemotherapy, radiation or a combination of the two. Targeted therapy and immunotherapy also may be used.

A multidisciplinary approach that includes surgery, medical oncology, and radiation oncology is required for optimal treatment of patients with rectal cancer. Treatment planning involves a complex decision-making process, and your healthcare team will work closely with you to ensure that your care plan offers the best possible outcomes.

Surgery

Surgery is the most common treatment for rectal cancer. The goal of surgery is to remove the cancer and enough nearby tissues to try to cure the cancer or stop it from spreading, while preserving typical bowel and bladder function when possible. If you have rectal cancer, surgery to remove small cancerous tumors may cure the condition.

The type of procedure that's recommended depends on how far the cancer has grown and where it is in the rectum. The choice of surgical procedure is based on the size, location, extent, and grade of the rectal carcinoma.

Several types of surgery may be used:

Local excision procedures: Typically used when rectal cancer is in an early stage and hasn't spread to the lymph nodes. This type of surgery removes the tumor through the anus, without making cuts in the abdomen
Sphincter-sparing procedures: These procedures are now considered the standard of care and aim to preserve both anal and rectal reservoir function
Other surgical approaches depending on the stage and location of the cancer

Sometimes a procedure to reroute stool leaving the body, such as an ileostomy or colostomy, may be needed.

Chemotherapy

Chemotherapy uses drugs to kill cancer cells or stop them from growing. You might have chemotherapy on its own or with radiotherapy. Fluorouracil, capecitabine, oxaliplatin and irinotecan are drugs used for rectal cancer. Chemotherapy is with combination regimens, along with biologic agents in metastatic cases.

Radiation therapy

Radiation therapy uses high energy waves similar to x-rays to kill bowel cancer cells. It is a treatment for cancer of the back passage (rectal cancer).

Chemoradiotherapy

Treatment with chemotherapy and radiotherapy together is called chemoradiotherapy. You might have this treatment for cancer of the back passage (rectal cancer). Except for stage I rectal cancer, neoadjuvant and adjuvant chemotherapy and radiation therapy are standard aspects of treatment.

Treatment timing

These therapies may be used before, during or after surgery. They can be used to shrink cancer or help kill any remaining cancer cells that were not removed with surgery. The management of rectal cancer has undergone significant changes over the past 50 years, with shifting of chemoradiotherapy treatment to favor a neoadjuvant approach (treatment given before surgery).

Outlook and survival

Certain factors affect prognosis (chance of recovery) and treatment options. When diagnosed in early stages, cure rates can be high.

The stage of the cancer (how far advanced the cancer is at diagnosis and spread of disease) is generally the most important factor. Other things that can affect outcomes include location of the tumor in the rectum, whether the tumor is causing blockage of the bowel or perforation (a hole in the rectum), as well as the patient's general health and ability to tolerate treatment.

Response to pre-operative therapy and pathological staging are the most important prognostic indicators of rectal cancer.

Some survival rate numbers you might hear from your doctor include:

5-year survival rate for localized cancer: 90-91%
5-year survival rate for regional cancer: 72-74%
5-year survival rate for distant cancer: 13-17%
If cancer has already spread to many different body systems, 5-year survivability is lower

Keep in mind that any numbers your doctor gives you are averages and estimates. The incidence of new cases and mortality of rectal cancer has been steadily declining for the past years.

Prevention and screening

Most colon and rectal cancers start as polyps, which are growths of abnormal tissue inside the colon and rectum. Rectal cancers can be prevented by discovering and removing these polyps with colonoscopy. 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.

Screening recommendations

Evidence supports screening for rectal cancer as a part of routine care for all adults aged 50 years and older, especially for those with first-degree relatives with colorectal cancer. Recently, the recommended age when screening should start was lowered to 45. All patients should discuss recommendations for colon and rectal cancer screening with their health care providers. This may be different for individuals depending on personal and family health history.

Lifestyle modifications

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

Living with rectal cancer

For many individuals diagnosed with colorectal cancer, completing treatment is a significant milestone. While it brings relief, it can also bring uncertainty about the future and concern over the possibility of recurrence. Others may find themselves managing cancer as a chronic condition, requiring ongoing treatment.

Follow-up care

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. Regular follow-ups are essential to monitor for recurrence, new cancers, or late effects of treatment.

Depending on your cancer stage and treatment history, your doctor may recommend:

Colonoscopy: Typically done one year after surgery, then every three to five years if results are normal
Proctoscopy: For rectal cancer patients who had transanal surgery, this may be recommended every 3-6 months for the first two years
Imaging tests: CT scans may be conducted every 6-12 months for those at higher risk of recurrence
Blood tests: CEA monitoring every 3-6 months for a few years after treatment

Survivorship care plan

A survivorship care plan is a crucial tool for post-treatment life. Work with your doctor to develop a plan that includes:

A schedule for follow-up exams and tests
Awareness of potential long-term side effects and when to seek medical attention
Recommendations for maintaining overall health, such as nutrition and exercise
Guidelines for cancer screening and preventative care

Managing side effects

Since colon cancer treatments often affect the digestive system, many survivors experience bowel irregularities, including diarrhea, constipation, or fecal incontinence. Your palliative care team can work with you to make changes to your diet, nutrition and fluids to help prevent intestinal blockages and other intestinal symptoms.

Some people may benefit from transanal irrigation (TAI), a technique that can help manage bowel control issues that may result from surgery.

Support and quality of life

Your palliative care team will also work with you and your other doctors to make sure that your treatment plan matches your goals. They will take the time to get to know you and understand what is important to you. Palliative care can help you find relief from pain and symptoms so that you can keep up with your treatments and get back to the things you enjoy.

Even if you have a great prognosis, get out and do things that you love. Visit with family members you haven't seen in a while. Make all those little moments count.