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Colorectal cancer is a cancer that starts in the colon (large intestine) or rectum. Both of these organs are in the lower portion of your digestive system. The rectum is at the end of the colon.

The American Cancer Society (ACS) estimates that about 1 in 23 men and 1 in 25 women will develop colorectal cancer during their lifetime.

Your doctor may use staging as a guideline to figure out how far along the cancer is. It’s important for your doctor to know the stage of the cancer so they can come up with the best treatment plan for you and give you an estimate of your long-term outlook.

Stage 0 colorectal cancer is the earliest stage, and stage 4 is the most advanced stage:

  • Stage 0. Also known as carcinoma in situ, in this stage abnormal cells are only in the inner lining of the colon or rectum.
  • Stage 1. The cancer has penetrated the lining, or mucosa, of the colon or rectum and may have grown into the muscle layer. It hasn’t spread to nearby lymph nodes or to other parts of the body.
  • Stage 2. The cancer has spread to the walls of the colon or rectum or through the walls to nearby tissues but hasn’t affected the lymph nodes.
  • Stage 3. The cancer has moved to the lymph nodes but not to other parts of the body.
  • Stage 4. The cancer has spread to other distant organs, such as the liver or lungs.

Colorectal cancer may not present with any symptoms, especially in the early stages. If you do experience symptoms during the early stages, they may include:

If you notice any of these symptoms, make an appointment with your doctor to discuss getting a colorectal cancer screening.

Stage 3 or 4 symptoms (late stage symptoms)

Colorectal cancer symptoms are more noticeable in the late stages (stages 3 and 4). In addition to the above symptoms, you might also experience:

If colorectal cancer spreads to other parts of your body, you may also experience:

While colorectal cancer sounds self-explanatory, there’s actually more than one type. The differences have to do with the types of cells that turn cancerous as well as where they form.

The most common type of colorectal cancer starts from adenocarcinomas. According to the ACS, adenocarcinomas make up most colorectal cancer cases. Unless your doctor specifies otherwise, your colorectal cancer is likely this type.

Adenocarcinomas form within the cells that make mucus in either the colon or rectum.

Less commonly, colorectal cancers are caused by other types of tumors, such as:

  • lymphomas, which can form in lymph nodes or in the colon first
  • carcinoids, which start in hormone-making cells within your intestines
  • sarcomas, which form in soft tissues such as muscles in the colon
  • gastrointestinal stromal tumors, which can start off as benign and then become cancerous (They usually form in the digestive tract, but rarely in the colon.)

Researchers are still studying the causes of colorectal cancer.

Cancer may be caused by genetic mutations, either inherited or acquired. These mutations don’t guarantee you’ll develop colorectal cancer, but they do increase your chances.

Some mutations may cause abnormal cells to accumulate in the lining of the colon, forming polyps. These are small, benign growths.

Removing these growths through surgery can be a preventive measure. Untreated polyps can become cancerous.

There’s a growing list of risk factors that act alone or in combination to increase a person’s chances of developing colorectal cancer.

Fixed risk factors

Some factors that increase your risk of developing colorectal cancer are unavoidable and can’t be changed. Age is one of them. Your chances of developing this cancer increase after you reach the age of 50.

Some other fixed risk factors are:

  • a prior history of colon polyps
  • a prior history of bowel diseases
  • a family history of colorectal cancer
  • having certain genetic syndromes, such as familial adenomatous polyposis (FAP)
  • being of Eastern European Jewish or African descent

Modifiable risk factors

Other risk factors are avoidable. This means you can change them to decrease your risk of developing colorectal cancer. Avoidable risk factors include:

An early diagnosis of colorectal cancer gives you the best chance of curing it.

The American College of Physicians (ACP) recommends screenings for people who are 50 to 75 years old, at average risk of the condition, and have a life expectancy of at least 10 years.

The British Medical Journal (BMJ) recommends screenings for people who are 50- to 79-years-old and whose 15-year risk of developing the condition is at least 3 percent.

Your doctor will start by getting information about your medical and family history. They’ll also perform a physical exam. They may press on your abdomen or perform a rectal exam to determine whether lumps or polyps are present.

Fecal testing

You may undergo fecal testing every 1 to 2 years. Fecal tests are used to detect hidden blood in your stool. There are two main types, the guaiac-based fecal occult blood test (gFOBT) and the fecal immunochemical test (FIT).

Guaiac-based fecal occult blood test (gFOBT)

Guaiac is a plant-based substance that’s used to coat the card containing your stool sample. If any blood is present in your stool, the card will change color.

You’ll have to avoid certain foods and medications, such as red meat and nonsteroidal anti-inflammatory drugs (NSAIDs), before this test. They may interfere with your test results.

Fecal immunochemical test (FIT)

The FIT detects hemoglobin, a protein found in the blood. It’s considered more precise than the guaiac-based test.

That’s because the FIT is unlikely to detect bleeding from the upper gastrointestinal tract (a type of bleeding that is rarely caused by colorectal cancer). Moreover, results for this test aren’t affected by foods and medications.

At-home tests

Because multiple stool samples are needed for these tests, your doctor will likely provide you with test kits to use at home as opposed to having you undergo in-office testing.

Both tests can also be performed with at-home test kits purchased online from companies such as LetsGetChecked and Everlywell.

Many kits purchased online require you to send a stool sample off to a lab for evaluation. Your test results should be available online within 5 business days. Afterward, you’ll have the option to consult with a medical care team about your test results.

The Second Generation FIT can also be purchased online, but the stool sample doesn’t have to be sent to a lab. Test results are available within 5 minutes. This test is accurate, FDA-approved, and able to detect additional conditions such as colitis. However, there’s no medical care team to reach out to if you have questions about your results.

Products to try

At-home tests can be used to detect blood in the stool, an important symptom of colorectal cancer. Shop for them online:

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Blood testing

Your doctor may run some blood tests to get a better idea of what’s causing your symptoms. Liver function tests and complete blood counts can rule out other diseases and disorders.

Sigmoidoscopy

Minimally invasive, sigmoidoscopy allows your doctor to examine the last section of your colon, which is known as the sigmoid colon, for abnormalities. The procedure, also known as flexible sigmoidoscopy, involves a flexible tube with a light on it.

The ACP recommends a sigmoidoscopy every 10 years, while the BMJ recommends a one-time sigmoidoscopy.

Colonoscopy

A colonoscopy involves the use of a long tube with a small camera attached. This procedure allows your doctor to see inside your colon and rectum to check for anything unusual. It’s usually performed after less invasive screening tests indicate that you might have colorectal cancer.

During a colonoscopy, your doctor can also remove tissue from abnormal areas. These tissue samples can then be sent to a laboratory for analysis.

Out of the existing diagnostic methods, sigmoidoscopies and colonoscopies are the most effective at detecting the benign growths that may develop into colorectal cancer.

The ACP recommends a colonoscopy every 10 years, while the BMJ recommends a one-time colonoscopy.

X-ray

Your doctor may order an X-ray using a radioactive contrast solution that contains the chemical element barium.

Your doctor inserts this liquid into your bowels through the use of a barium enema. Once in place, the barium solution coats the lining of the colon. This helps improve the quality of the X-ray images.

CT scan

CT scans provide your doctor with a detailed image of your colon. A CT scan that’s used to diagnose colorectal cancer is sometimes called a virtual colonoscopy.

Treatment of colorectal cancer depends on a variety of factors. The state of your overall health and the stage of your colorectal cancer will help your doctor create a treatment plan.

Surgery

In the earliest stages of colorectal cancer, it might be possible for your surgeon to remove cancerous polyps through surgery. If the polyp hasn’t attached to the wall of the bowels, you’ll likely have an excellent outlook.

If your cancer has spread into your bowel walls, your surgeon may need to remove a portion of the colon or rectum along with any neighboring lymph nodes. If at all possible, your surgeon will reattach the remaining healthy portion of the colon to the rectum.

If this isn’t possible, they may perform a colostomy. This involves creating an opening in the abdominal wall for the removal of waste. A colostomy may be temporary or permanent.

Chemotherapy

Chemotherapy involves the use of drugs to kill cancer cells. For people with colorectal cancer, chemotherapy commonly takes place after surgery, when it’s used to destroy any lingering cancerous cells. Chemotherapy also controls the growth of tumors.

Chemotherapy drugs used to treat colorectal cancer include:

  • capecitabine (Xeloda)
  • fluorouracil
  • oxaliplatin (Eloxatin)
  • irinotecan (Camptosar)

Chemotherapy often comes with side effects that need to be controlled with additional medication.

Radiation

Radiation uses a powerful beam of energy, similar to that used in X-rays, to target and destroy cancerous cells before and after surgery. Radiation therapy commonly occurs alongside chemotherapy.

Other medications

Targeted therapies and immunotherapies may also be recommended. Drugs that have been approved by the Food and Drug Administration (FDA) to treat colorectal cancer include:

  • bevacizumab (Avastin)
  • ramucirumab (Cyramza)
  • ziv-aflibercept (Zaltrap)
  • cetuximab (Erbitux)
  • panitumumab (Vectibix)
  • regorafenib (Stivarga)
  • pembrolizumab (Keytruda)
  • nivolumab (Opdivo)
  • ipilimumab (Yervoy)

They can treat metastatic, or late-stage, colorectal cancer that doesn’t respond to other types of treatment and has spread to other parts of the body.

Having a colorectal cancer diagnosis can be worrying, but this type of cancer is extremely treatable, especially when caught early.

The 5-year survival rate for all stages of colon cancer is estimated to be 63 percent based on data from 2009 to 2015. For rectal cancer, the 5-year survival rate is 67 percent.

The 5-year survival rate reflects the percentage of people who survived at least 5 years after diagnosis.

Treatment measures have also come a long way for more advanced cases of colon cancer.

According to the University of Texas Southwestern Medical Center, in 2015, the average survival time for stage 4 colon cancer was around 30 months. In the 1990s, the average was 6 to 8 months.

At the same time, doctors are now seeing colorectal cancer in younger people. Some of this may be due to unhealthy lifestyle choices.

According to the ACS, while colorectal cancer deaths declined in older adults, deaths in people younger than 50 years old increased between 2008 and 2017.

Certain risk factors for colorectal cancer, such as family history and age, aren’t preventable.

However, lifestyle factors that may contribute colorectal cancer are preventable, and may help reduce your overall risk of developing this disease.

You can take steps now to reduce your risk by:

Another preventive measure is to make sure you get a colonoscopy or other cancer screening after the age of 50. The earlier the cancer is detected, the better the outcome.

When it’s caught early, colorectal cancer is treatable.

With early detection, most people live at least another 5 years after diagnosis. If the cancer doesn’t return in that time, there is a very low chance of recurrence, especially if you had early stage disease.