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

The American Cancer Society estimates 1 in 22 men and 1 in 24 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 1 colorectal cancer is the earliest stage. The stages progress up to stage 4, which is the most advanced stage. Here are the stages of colorectal cancer:

  • Stage 1. The cancer has penetrated the lining, or mucosa, of the colon or rectum but hasn’t spread to the organ walls.
  • Stage 2. The cancer has spread to the walls of the colon or rectum but hasn’t affected the lymph nodes or nearby tissues yet.
  • Stage 3. The cancer has moved to the lymph nodes but not to other parts of the body yet. Usually, one to three lymph nodes are involved at this stage.
  • Stage 4. The cancer has spread to other distant organs, such as the liver or lungs.

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

  • constipation
  • diarrhea
  • changes in stool color
  • changes in stool shape, such as narrowed stool
  • blood in the stool
  • bleeding from the rectum
  • excessive gas
  • abdominal cramps
  • abdominal pain

If you notice any of these symptoms, make an appointment with your doctor to discuss getting a colon 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:

  • excessive fatigue
  • unexplained weakness
  • unintentional weight loss
  • changes in your stool that last longer than a month
  • feeling like your bowels don’t completely empty
  • vomiting

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

  • jaundice (yellow eyes and skin)
  • swelling in hands or feet
  • breathing difficulties
  • chronic headaches
  • blurry vision
  • bone fractures

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

The most common type of colon cancer starts from adenocarcinomas. According to the American Cancer Society, adenocarcinomas make up 96 percent of all colon cancer cases. Unless your doctor specifies otherwise, your colon cancer is likely this type. Adenocarcinomas form within mucus cells in either the colon or rectum.

Less commonly, colorectal cancers are caused from 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 (These usually form in the digestive tract, but rarely in the colon.)

Researchers are still studying the causes of colorectal cancer. While there’s a growing list of risk factors, they act alone or in combination to increase one’s risk for developing colorectal cancer.

Precancerous growths

Abnormal cells accumulate in the lining of the colon, forming polyps. These are small, benign growths. Removing these growths through surgery is a common preventive method. Untreated polyps can become cancerous.

Gene mutations

Sometimes colorectal cancer occurs in family members. This is due to a gene mutation that passes from parent to child. These mutations don’t guarantee you’ll develop colorectal cancer, but they do increase your chances.

There are some factors that may increase your risk of developing colorectal cancer:

Unavoidable 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 unavoidable risk factors are:

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

Avoidable factors

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

  • being overweight or obese
  • smoking
  • heavy drinking of alcohol
  • having type 2 diabetes
  • having a sedentary lifestyle
  • consuming a diet high in processed foods or red meats

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

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 the presence of lumps or polyps.

Blood testing

Your doctor may run some blood tests to get a better idea of what’s causing your symptoms. Though there’s no blood test that specifically checks for colorectal cancer, liver function tests and complete blood count tests can rule out other diseases and disorders.

Colonoscopy

A colonoscopy involves the use of a long tube with a small, attached camera. This procedure allows your doctor to see inside your colon and rectum to check for anything unusual.

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

X-ray

Your doctor may order an X-ray using a radioactive contrast solution that contains the metallic element barium. Your doctor will insert this liquid into your bowels through the use of an 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. When used in diagnosing colorectal cancer, another name for a CT scan is 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. In the case of colorectal cancer, chemotherapy is a common treatment after surgery to destroy any remaining cancerous cells. Chemotherapy also controls the growth of tumors.

While chemotherapy provides some symptom relief in late-stage cancer, it 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.

Medication

In September 2012, the approved the drug regorafenib (Stivarga) to 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. This drug works by blocking enzymes that promote the growth of cancer cells.

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

Treatment measures have also come a long way for more advanced cases of colon cancer. According to the University of Texas Southwestern Medical Center, the average survival rate for stage 4 colon cancer is around 30 months. This is up from the 6 to 8 months that was the average during the 1990s.

At the same time, doctors are now seeing colon cancer in younger patients. This is likely due to poor lifestyle choices that are more common than decades earlier. The American Cancer Society says that, while colon cancer deaths have decreased overall, related deaths in patients younger than 55 have increased 1 percent per year between 2007 and 2016.

Certain risk factors for colon 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:

  • decreasing the amount of red meat you eat
  • avoiding processed meats, such as hot dogs and deli meats
  • eating more plant-based foods
  • decreasing dietary fat in your diet
  • exercising daily
  • losing weight, if your doctor recommends it
  • quitting smoking
  • reducing alcohol consumption
  • decreasing stress
  • controlling preexisting diabetes

Another preventive measure is to make sure you get a colonoscopy after the age of 50 — even if you don’t have risk factors for colon cancer. The earlier the cancer is detected, the better the outcome.

When it’s caught early, colorectal cancer is treatable and often curable. With early detection, most people live at least another five years after diagnosis. If the cancer doesn’t return in that time, you’re considered cured, especially if you’re in the first three stages of the disease.