What to Know About Rectal Cancer Symptoms, Treatments, and Prevention

What is rectal cancer?

With all of the attention colon cancer gets, it can be easy to forget about rectal cancer.

That’s a mistake because thousands of people are diagnosed with the disease each year. In fact, there will be an estimated 45,230 new cases of rectal cancer diagnosed in 2021, according to the American Cancer Society (ACS).

Doctors often group both colon and rectal cancer into colorectal cancer, one of the most common types of cancer. But rectal cancer is unique in its diagnosis and treatment.

First, it helps to understand where the rectum is located in the body, and its role in the digestive tract. The food you eat makes its way to your small intestine, where nutrients are absorbed.

What’s left moves on to the large intestine, or colon. It arrives pretty watery, says Benjamin Schlechter, MD, a medical oncologist who specializes in gastrointestinal cancers at Dana-Farber Cancer Institute in Boston.

“The job of the colon is to get rid of the water and form a bowel movement,” he says. That change from watery to solid ensures you can hold your bowels and won’t have to poop constantly.

Your stool then moves into the rectum, the final, straight portion of the large intestine, explains Emmanouil Pappou, MD, a colorectal surgeon at Memorial Sloan Kettering Cancer Center in New York City. It’s about six inches (15 cm) long and is considered the last part of the large intestine.

Once food waste arrives there, you get a signal that it’s time to have a bowel movement.

What causes rectal cancer?

The exact cause of rectal cancer is not clear, but benign growths called polyps can develop on the rectal wall.

The polyps aren’t necessarily cancerous, but the cells in some of these polyps can change into cancer over time.

Many of the things that raise your risk for colon and anal cancers also up the risk for rectal cancer. Talk to your doctor about your personal risk if you meet any of the criteria below, all of which the National Cancer Institute (NCI) considers risk factors for rectal cancer.

• A personal history of rectal, colon, or ovarian cancer
• A family history of rectal or colon cancer
• Benign colorectal polyps
• Adenomas (benign colorectal polyps with abnormal cells)
• Inflammatory bowel disease (IBD), such as Crohn’s disease and ulcerative colitis
• Inherited syndromes, such as Lynch syndrome or familial adenomatous polyposis
• Smoking
• Having three or more alcohol-containing drinks a day
• Obesity
• Being African American
• Older age (especially after age 50)

Other things that may raise your risk, include having type 2 diabetes, eating red and processed meats, and being inactive.

(Here are other surprising risk factors that cause cancer.)

How to prevent rectal cancer

Along with getting a regular colorectal cancer screening, you can help prevent colorectal cancer by taking these measures:

• Exercise regularly
• Avoid smoking
• Limit alcohol intake
• Maintain a healthy weight
• Eat more fruits and vegetables and less red meat and processed meat

Screening for rectal cancer

Though there are signs and symptoms of rectal cancer to look for, they’re not always present.

“Usually cancer does not have symptoms,” says Dr. Pappou. “That’s why we recommend screening.”

The American Cancer Society recommends colorectal cancer screenings beginning at age 45 for people with an average risk for the disease. There are a variety of tests to check for rectal cancer, most of with fall into one of two categories: stool-based tests and visual tests.

Stool-based screenings look at the stool for signs of cancer. They include the fecal immunochemical test (FIT), guaiac-based fecal occult blood test (gFOBT), and the stoll DNA test (also called the FIT DNA test).

Visual exams take a look inside the rectum and colon to check for polyps and cancer, either via a scan or an endoscope, a flexible, lighted instrument used to examine the tract. These tests include the colonoscopy, virtual colonoscopy (also called a CT colonography), and flexible sigmoidoscopy.

Each test comes with pros and cons, which you’ll want to discuss with your doctor.

The colonoscopy has a leg up on some of the other screening tests, says Dr. Pappou, because it allows doctors to look at the entire colon and remove any growths that could eventually become cancerous.

“The idea is that if I find a small polyp, I can scrape it out and prevent it from turning into cancer,” he says.

(Here’s how to know if you need to start colorectal cancer screenings early.)

Symptoms of rectal cancer

Though rectal cancer may occur without symptoms, certain health issues may point to a problem. If you’re experiencing any of the symptoms below, make an appointment with your doctor.

Anemia

Anemia is a lack of red blood cells or hemoglobin, both of which play a role in oxygen transportation to body tissues. If you have anemia, you may feel fatigue or dizziness, or have an increased heart rate, paler-than-usual skin, or irregular periods.

The condition can be an early warning sign of cancer. As a tumor grows over time, it can bleed. This may appear as iron-deficiency anemia on a blood test. If a blood test has shown signs of anemia, your doctor will need to explore further to identify the source and rule out causes like cancer.

Rectal bleeding

There are a few different reasons you may spot bright red blood on your toilet paper or in the toilet after you go to the bathroom. It’s easy to blame this on hemorrhoids (swollen veins in your rectum and anus), but that’s not a safe assumption. Bleeding can be a sign of colorectal cancer.

Before you worry, know that among patients with bleeding, most will not have cancer. Chances are, the bleeding is indeed caused by hemorrhoids.

But if you are one of the people who has cancer, you need to know. A rectal exam can confirm hemorrhoids—but not rule out colon cancer, so talk to your doctor about possible screening.

(Here’s what blood in your stool could mean.)

Change in bowel habits

In general, your bathroom habits should be fairly regular. That’s why out-of-the ordinary constipation, diarrhea, or narrow stools is cause for concern when it lasts for more than a few days.

A change in bowel habits is the most common symptom of rectal cancer, says the American Society of Colon & Rectal Surgeons (ASCRS). If after a few days a new and unexplained bathroom habit hasn’t gone away, book an appointment with your doctor.

Unexplained weight loss and fatigue

Though weight loss is a symptom for many types of cancer, it can be easy to overlook or think its due to stress. The ACS advises consulting a doctor if you lose 10 or more pounds for no obvious reason. A lack of appetite can be another symptom of rectal cancer.

The same goes for fatigue that doesn’t get better with rest. Keep in mind that there are many other reasons for fatigue, but you should raise the issue with your doctor.

Abdominal pain

Pay attention to abdominal pain, bloating, a feeling of fullness, frequent gas pains, and cramps.

Don’t simply brush off abdominal cramps as period related; if the pain doesn’t go away, you’ll should talk to a doctor.

How is rectal cancer diagnosed?

There are several methods for diagnosing rectal cancer, some of which can also indicate the cancer stage you’re in. Here are the tests used to detect and diagnose rectal cancer, according to the NCI:

• Physical exam: During a physical exam, your doctor will check your body for signs of disease (like lumps) and discuss your health history.
• Digital rectal exam: Your provider will physically examine your rectum with their gloved finger to check for tumors. If you’re a woman, the doctor may examine your vagina as well.
• Colonoscopy: Using a thin, lighted tube that’s inserted into your colon and rectum, your doctor will look for polyps or and tumors. A colonoscopy can be used as a screening tool in someone who does not have symptoms or as a diagnostic tool to determine the cause of a patient’s GI problem.
• Biopsy: If something abnormal shows up during a colonoscopy, your doctor may biopsy (remove) affected tissue to be analyzed for cancer.
• Carcinoembryonic antigen (CEA) assay: This blood test detects high levels of cells called CEA, a substance released into the bloodstream from cells. High levels of this can signal rectal cancer.
• Imaging tests: To determine if cancer has spread to lymph nodes or other organs, your doctor may order an MRI or ultrasound. These tests can also help determine which stage cancer you have.

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Types of rectal cancer

If you’re diagnosed with rectal cancer, your doctor will speak to you about the type of rectal cancer you have. There are four types of rectal cancer:

• Adenocarcinoma: Most rectal cancers are this type, which refers to cancer of cells that line the inside surface of the rectum.
• Carcinoid tumors: These are neuroendocrine tumors (NETs), which can appear around the body, including in the gastrointestinal system. They’re slow-growing tumors, which is why doctors consider them low grade.
• Gastrointestinal stromal tumors: These are cancers that begin in the soft tissue, blood vessel, or connective tissue in the rectum. Though these types of tumors can occur anywhere in the GI tract, they’re rare in the rectum.
• Lymphoma: This cancer starts in lymphocytes, white blood cells that are part of the body’s immune system. This process can begin in the rectum, though it usually originates in lymph nodes.

Stages of rectal cancer

Rectal cancer is referred to in stages 0 to 4. Your cancer stage is determined by three pieces of information, collectively known as the TNM system. Those three factors include:

• Stage 1: The size of the tumor and how far it’s grown into the wall of the rectum.
• Stage 2: Whether the cancer has spread to nearby lymph nodes.
• Stage 3: Whether the cancer has spread to distant lymph nodes or parts of the body.

The NCI breaks down each stages in the following way:

Stage 0

Also called “carcinoma in situ,”  this is the stage when cells are at high risk of becoming cancer. At this point, there are abnormal cells in the innermost layer (the mucosa) of the rectum wall.

Stage 1

Cancer is found in the mucosa of the rectum and spread to the next layer of tissue (called the submucosa) or to the muscle of the rectum. It hasn’t spread to nearby lymph nodes, however.

Stage 2

Once cancer reaches stage 2, it is divided into three stages. These indicate how far into the rectum wall the tumor has grown and whether it has spread to nearby lymph nodes and organs.

• Stage 2A: Cancer has spread through the muscle layer of the rectum wall into the outermost layer (called the serosa).
• Stage 2B: Cancer has spread through the serosa of the rectum to the visceral peritoneum, the tissue that lines the organs in the abdomen.
• Stage 2C: Cancer spread through the serosa of the rectum to nearby organs.

Stage 3

As with stage 2 rectal cancer, this is also further divided into three stages that indicate how far the cancer has grown in the rectum and how many lymph nodes are affected.

Stage 3A

• Cancer has spread through the mucosa to the submucosa or the muscle. Cancer is also found in one to three nearby lymph nodes, or cancer cells are found in the tissues near lymph nodes.
• Or cancer has spread through the mucosa to the submucosa, as well as four to six nearby lymph nodes.

Stage 3B

• Cancer has spread through the muscle to the serosa or from the serosa to the visceral peritoneum. Cancer is also found in one to three nearby lymph nodes or in the tissue near these lymph nodes.
• Or cancer has spread to the serosa and four to six nearby lymph nodes.
• Or cancer has spread through the mucosa to the submucosa or muscle layer, as well as seven or more nearby lymph nodes.

Stage 3C

• Cancer has spread through the serosa to the visceral peritoneum and four to six nearby lymph nodes.
• Or cancer has spread through the muscle layer to the serosa or through the serosa to the visceral peritoneum and to seven or more nearby lymph nodes.
• Or cancer has spread through the serosa to nearby organs, as well as one or more nearby lymph nodes, or cancer cells are found in tissue near the lymph nodes.

Stage 4

Rectal cancer that has reached areas beyond the rectum is considered stage 4. This too is divided into three subcategories, based on how far the cancer has spread.

• Stage 4A: Cancer has spread to one distant area or organ, such as the liver, lung, ovary, or a distant lymph node.
• Stage 4B: Cancer has spread to more than one distant area or organ.
• Stage 4C: Cancer has spread to the tissue that lines the wall of the abdomen and possibly to other areas or organs as well.

(Here are the 4 colon cancer stages.)

Treatment

Treatment for rectal cancer can be trickier than that for colon cancer. That has to do with the way the rectum is built and the potential for cancer to spread.

As Dr. Schlechter explains, the colon is surrounded by a membrane that acts as plastic wrap to keep the colon contained. The rectum does not, giving it flexibility to expand when it comes to storing stool. “When cancer goes through the muscle wall of the rectum, it’s in this big open space where it can contaminate the pelvis,” he says.

If you have advanced rectal cancer, Dr. Schlechter says it’s a good idea to have DNA sequencing done on your tumor. This can point you and your doctor to the most effective treatments.

“In 2021, minimal sequencing of just a few typical genes is not enough. You should have whole-genome sequencing done,” he says. “The results may identify particular treatments for your cancer or help match you up with clinical trials based on unique gene mutations in your cancer.”

Surgery

The most common treatment for rectal cancer is surgery. Using one of many types of surgery, your doctor will remove the cancer from your rectum.

Rectal cancer surgery is particularly tricky because of the rectum’s anatomy. “There is a much narrower space in the rectum, and the rectum is close to other organs,” says Dr. Pappou. “Surgery is more delicate.”

Depending on how extensive the cancer is, the surgeon may remove the rectum. Afterwards, you may need to use an external bag to collect waste, known as an ostomy bag.

There is good news, though: For virtually all rectal cancer surgeries, the ostomy bag is only a temporary tool used while the rebuilt rectum heals.

“In most cases, surgeons can perform a second surgery to close the ostomy and restore bowel function,” Dr. Schlechter says. “You may have changes in how often you go to the bathroom, but most people have a ‘new normal’ that is not too far off their bowel function before developing cancer.”

It’s important to talk to your doctor about what you can expect during and after surgery, as well as how to manage these changes.

Chemotherapy and radiation

Most people with rectal cancer will receive radiation and low-dose chemotherapy for just shy of six weeks. This is followed by chemotherapy, either before or after surgery, says Dr. Schlechter.

If the tumor shrinks completely (as seen on an MRI), there is a controversial movement to use observation (aka the “watch and wait” approach) before jumping into surgery.

There is a lack of evidence about the effect this has on the chance of cure. Dr. Schlechter says that while he’d never recommend that someone avoid surgery, some patients prefer this route.

If you choose to wait and see, your doctor will need to monitor you very closely.

Other rectal cancer treatments

Depending on your stage of cancer and other health factors, your doctor may look to targeted therapy or immunotherapy as treatments for your rectal cancer.

Targeted therapy as the use of drugs or other substances to attack cancer cells without hurting normal cells. These therapies may include lab-made immune system antibodies or drugs to stop the growth of new blood vessels, which tumors need to grow.

Immunotherapy, on the other hand, harnesses your immune system to fight the cancer. These substances made by your body or in a lab boost or restore your natural cancer defenses.

Outcomes and prognosis

Rectal cancer is a very curable cancer, says Dr. Schlechter. According to the ACS, the following are the five-year survival rates for rectal cancer:

• Localized Cancer: When cancer hasn’t spread outside the rectum, the survival rate is 89 percent.
• Regional Cancer: When cancer has spread outside the rectum to nearby lymph nodes, the survival rate is 72 percent.
• Distant Cancer: When cancer has spread to distant parts of the body (such as the liver, lungs, or distant lymph nodes), the survival rate is 16 percent.

Next, here’s what you need to know about millennials and colon cancer.