Everything You Need to Know About Colon Cancer

Table of Contents

Signs and Symptoms
Risk Factors
When to See a Doctor
Staging of Colon Cancer
Living with Colon Cancer
Frequently Asked Questions


Colon cancer refers to the uncontrolled growth of cells in the colon. This disease almost always develops from abnormal growths in the colon called precancerous polyps. As such, colon cancer screening is so important in the fight against this disease.

In the United States, colon cancer is the third most common cancer diagnosed in both men and women. Plus, it has the distinction of being the third leading cause of death from cancer among American men and women.

Signs and Symptoms

Signs and symptoms of colon cancer vary. Early in the course of the disease, many people may have no symptoms at all.

As the colon cancer progresses, early-stage signs and symptoms may manifest. This includes:

  • Blood in your stool, which can be visible or not visible;
  • Diarrhea or constipation;
  • Changes in the caliber and/or consistency of your stool, and;
  • Abdominal pain/discomfort, which may be accompanied by cramping, bloating, or gas.

Late-stage signs and symptoms of colon cancer may include:

  • Unexplained weakness;
  • Excess fatigue;
  • Unexplained/unintentional weight loss;
  • Feeling of incomplete emptying of your bowels, and;
  • Nausea and vomiting.

Lastly, if colon cancer spreads, or metastasizes, to other parts of the body, the signs and symptoms may include:

  • Jaundice;
  • Shortness of breath;
  • Swelling of the hands and feet;
  • Headaches, which can be chronic, and;
  • Unusual bone fractures.

Risk Factors

There is a multitude of risk factors that may increase your chances of developing colon cancer. Some of these risk factors cannot be changed, while others can be.

The most common non-modifiable risk factor for colon cancer is advancing age. The American Cancer Society estimates that 90 percent of colon cancer diagnoses occur in individuals who are 50 or older. Some other non-modifiable risk factors are:

Some modifiable risk factors for colon cancer include:

  • Overweight or obesity;
  • Smoking;
  • Excessive alcohol consumption;
  • Lack of regular physical activity, and;
  • Low-fiber, high-fat diet.


Since most colon cancers develop from precancerous polyps, screening efforts to find them early are imperative. It is imperative because this is when the treatment works best.

Colon cancer screening does indeed save lives. In fact, almost 90 percent of individuals whose colon cancers are found early, localized, and treated fittingly are still alive five years after treatment.

The U.S. Preventive Services Task Force recommends colon cancer screening commence at age 50 with strategies including:

  • Stool Tests: Ones that are appropriate for colon cancer screening include the fecal occult blood test, fecal immunochemical test (FIT), and FIT-DNA (or stool DNA) test. They are typically repeated yearly if negative. The exception is the FIT-DNA test, which you should get every one to three years.
  • Flexible Sigmoidoscopy: “Flex sig” for short. It uses a thin, flexible tube with a light source to check for colon polyps/cancer in the last two feet of the colon. It is repeated every five years — or every 10 years if combined with a FIT — if negative.
  • Colonoscopy: Similar to a flex sig, except your doctor will visualize your entire colon. It is repeated every 10 years in individuals who do not have an increased risk of colon cancer. Currently, it is the preferred colon cancer screening method, as any encountered polyps can be removed. Plus, it is the follow-up test of choice for any abnormalities found during one of the other screening tests.

Lastly, other screening techniques include double-contrast barium enema or virtual colonoscopy. These may be repeated every five to 10 years or five years, respectively, if negative.


As far as colon cancer prevention or at least decreasing your risk, you should consider:

  • A low-fat diet rich in fruits, vegetables, and whole grains;
  • Regular exercise for at least 30 minutes, five or more times per week;
  • Avoiding alcohol or at least limiting consumption;
  • Avoiding tobacco use, and;
  • Aspirin therapy.

When to See a Doctor

If you suspect you may be experiencing signs or symptoms of colon cancer, you should make an appointment with your doctor to discuss the matter. Furthermore, if you are at average risk for colon cancer, you should see your doctor for colon cancer screening commencing at age 50. This has the potential to become a prevention method, especially in the case of colonoscopy.

Lastly, if you suspect your risk for colon cancer has increased, you should discuss this with your doctor to determine when to begin screening, which test is appropriate for you, and how often to obtain screening.


Your doctor will start by performing a thorough medical history focusing on your symptoms and family history. This is followed by a thorough physical examination, including a rectal examination.

Although there is no specific blood test for the diagnosis of colon cancer, your doctor may check your liver function tests and complete blood count. Colon cancer — especially if has spread to other parts of the body — or other medical conditions may adversely affect these tests.

Other diagnostic strategies for colon cancer may include imaging studies, such as double-contrast barium enema and virtual colonoscopy.

Staging of Colon Cancer

If diagnosed with colon cancer, you and your doctor will want to know the extent of your cancer. This is accomplished through a process called staging. This process helps determine which treatments are most appropriate for you. Abdominal, pelvic, chest CT scans, and biopsies are usually utilized in the staging of colon cancer.

Roman numerals ranging from 0 to IV are used to indicate the stages of colon cancer. They are:

  • Stage 0: This is the earliest stage of colon cancer. The cancer has not grown beyond the mucosa (innermost layer of the colon).
  • Stage I: The colon cancer has grown beyond the mucosa and into the submucosa (middle layer of the colon).
  • Stage II: The colon cancer has grown beyond the mucosa and submucosa into the outer layers of the colon (muscularis propria and serosa).
  • Stage III: The colon cancer has grown beyond the outer layers of the colon and to one to three lymph nodes. However, it has not spread to distant sites in the body.
  • Stage IV: Also known as metastasis. As such, it is the most advanced form of colon cancer. The colon cancer has grown beyond all layers of the colon, spread to lymph nodes, and distant parts of the body, such as lungs, liver, bone, or brain.


There are several types of colon cancers. The most common type is adenocarcinoma, which accounts for 96 percent of colon cancers. Two subtypes of adenocarcinoma, mucinous and signet ring cell, deserve special mention because they tend to have a worse prognosis as compared to other types of adenocarcinoma.

Other less common types of colon cancer include:

  • Carcinoid Tumors: Starts in the hormone-producing cells of the colon.
  • Gastrointestinal Stromal Tumors: Starts in the interstitial cells of Cajal.
  • Lymphomas: Namely a type of non-Hodgkin lymphoma that originates in the colon.
  • Sarcomas: Namely leiomyosarcomas or cancers of smooth muscle.


The prognosis for your colon cancer is most commonly referred to as the five-year survival rate.  For particular colon cancers, its stage at diagnosis determines the prognosis.

The Surveillance Epidemiology and End Results (SEER) database from the National Cancer Institute estimates the following five-year relative survival rates based on colon cancer stage:

SEER Stage5-Year Relative Survival Rate Colon Cancer
Localized (confined to only part of body)90%
Regional (spread to lymph nodes)71%
Distant (metastasized)14%
All SEER stages combined64%


If left untreated, the complications of colon cancer may include:

  • Bleeding, which can be visible from the rectum and leads to iron deficiency anemia;
  • Blockage of the colon or bowel obstruction, or;
  • A hole in the colon or bowel perforation.

These complications may be considered surgical emergencies and can become life-threatening.

Other potential complications of colon cancer include:

  • Recurrence of cancer in the colon;
  • Spread of cancer to other organs or tissues with subsequent dysfunction/failure, and;
  • Diagnosis of second primary colon cancer.


The treatment of colon cancer depends on many variables, including the stage of cancer. The aims of colon cancer treatment are the removal of cancer, prevention of its spread, and reduction of any uncomfortable symptoms.

Colon cancer treatments come in two broad categories:

  1. Local Therapies: Treat colon cancer without affecting the rest of the body. These include surgery and radiation therapy.
  2. Systemic Therapies: Treat colon cancer using drugs. You can receive these drugs orally or directly into the bloodstream. These include chemotherapy, targeted therapy, and immunotherapy.


Surgery for colon cancer may include:

  • Polypectomy: Removal of the cancerous polyp. Used for stage 0 and some stage I colon cancers.
  • Local Excision: Removal of some tissue in the wall of the rectum. The rectum is the vault at the end of the colon. Used for stage 0 and some stage I colon cancers.
  • Colectomy: Removal of the colon. Used for more advanced colon cancer (stages II through IV). There are two types: partial and total colectomy. All types of partial colectomy, as well as total colectomy, can be performed via minimally invasive laparoscopy or via a large abdominal incision. It may be accompanied by an ostomy, which can be temporary or permanent.

Radiation Therapy

Radiation therapy is not commonly used in the treatment of colon cancer. Despite that, it may be useful in select cases, such as:

  • Before surgery to decrease tumor size and allow for easier removal;
  • During surgery to kill any residual cancer cells;
  • After surgery to kill any residual cancer cells;
  • To ease complications such as bleeding, bowel obstruction, or pain, and;
  • To help treat metastatic colon cancer.

Side effects of radiation therapy may include:

  • Burns;
  • Nausea;
  • Vomiting;
  • Fatigue;
  • loss of appetite, and;
  • Weight loss.

Most of these side effects resolve within several weeks after cessation of treatment.


Almost all individuals diagnosed with stage III colon cancer receive chemotherapy after surgery for a total of six to eight months. This is adjuvant chemotherapy.

Occasionally, chemotherapy with or without radiation therapy may be used before surgery to shrink the tumor and make it easier to remove. This is neoadjuvant chemotherapy.

Also, in individuals with stage IV disease, chemotherapy may be used to help ease symptoms by shrinking the tumor. It may even prolong life in these individuals.

Some chemotherapy drugs used to treat colon cancer include:

  • 5-fluorouracil (5-FU);
  • Irinotecan (Camptosar);
  • Oxaliplatin (Eloxatin), and;
  • Trifluridine and tipiracil (Lonsurf).

Side effects of chemotherapy may include:

  • Hair loss;
  • Mouth sores;
  • Nausea;
  • Vomiting;
  • Diarrhea;
  • Fatigue, and;
  • Increased susceptibility to infections.

Targeted Therapy

Targeted therapy involves drugs that specifically block or inhibit either the growth of cancer cells or the formation of new blood vessels. These two functions are crucial to the perpetuation of colon cancer. Specifically, targeted therapy can block:

  • Epidermal Growth Factor Receptor (EGFR): A protein needed for cancer cell growth.
  • Vascular Endothelial Growth Factor (VEGF): A protein needed for the formation of new blood vessels; also referred to as angiogenesis.
  • Kinases: Several molecules that are responsible for both cancer cell growth and angiogenesis.

Examples of targeted therapy for colon cancer include:

  • Cetuximab (Erbitux) and panitumumab (Vectibix), which target EGFR;
  • Bevacizumab (Avastin) and ramucirumab (Cyramza), which target VEGF, and;
  • Regorafenib (Stivarga), which target kinases.

Targeted therapy will sometimes work when standard chemotherapy drugs don’t. Plus, they often have different and less severe side effects compared to standard chemotherapy regimens.

Targeted therapy drugs can be used alone or in combination with surgery, radiation, and standard chemotherapy.


Immunotherapy focuses on drugs that have the potential to boost your immune system. This boost will hopefully lead to better recognition and destruction of colon cancer cells. Immunotherapy accomplishes this by blocking key proteins on immune cells, which boosts your immune response.

These drugs are known as “checkpoint inhibitors”. If your colon cancer is still growing, despite chemotherapy, you may be a candidate for a checkpoint inhibitor. Examples include pembrolizumab (Keytruda), nivolumab (Opdivo), and ipilimumab (Yervoy).

Side effects of this class of medications may include:

  • Potentially life-threatening immune reactions;
  • Fatigue;
  • Diarrhea;
  • Rash, and;
  • Itching.

Living with Colon Cancer

For some, there is a beginning and end to their colon cancer treatment. For others, their colon cancer never totally goes away. This leaves them with regular treatments to keep the cancer at bay.

Whether you are living with or after colon cancer, there are things you can do to reduce your risk of first-time or recurrent disease. This includes:

  • Eating a Healthful Diet: Preferably a diet rich in a variety of fruits and vegetables, along with whole grains, plenty of chicken, and/or fish. This should provide the vitamins, minerals, fiber, and antioxidants that are crucial in combatting colon cancer. Make sure there is little or no red meat.
  • Exercising Regularly: Most experts agree that you should strive for a minimum of 30 minutes per day at least for times per week. Make sure to discuss with your doctor for an appropriate and realistic exercise prescription.
  • Drinking Alcohol in Moderation If at All: It’s best to abstain from drinking alcohol with a diagnosis as serious colon cancer. However, if you choose to drink alcohol, try to limit your intake to no more than one drink per day for a woman and no more than two drinks per day for a man.
  • Quitting Smoking: There are plenty of over the counter and prescription medications for smoking cessation that can be recommended by your doctor.
  • Maintaining a Normal Weight: As you already know, there is a connection between being overweight or obese and some types of cancer, including colon cancer. Fortunately, all the above measures combined should result in the appropriate weight loss.

Frequently Asked Questions

Should I Get a Colonoscopy?

The obvious answer to this question is yes.

In fact, it is estimated that 60 percent of deaths from colon cancer could be prevented with routine screening colonoscopy commencing at age 50. The proportion increases to 90 percent of deaths prevented when you add lifestyle changes to screening colonoscopy.

Do I Need to Miss Work for My Colonoscopy?

Yes. Since the sedatives are administered prior to the procedure, you will need time for the medication to wear off completely. Depending on the patient, this can take several hours.

Additionally, you will need someone to drive you home after your procedure for this same reason.

What Can I If I’m Concerned About the Costs and Insurance Coverage for My Colon Cancer Screening Test?

The Affordable Care Act requires both private insurers and Medicare to cover the costs of colon cancer screening tests starting at age 50. As a result, there should be no out-of-pocket costs for these tests in most cases.

What Is a Colorectal Surgeon?

Colorectal surgeons are experts in the surgical and non-surgical treatment of diseases of the colon, rectum, and anus. They are board-certified and well-versed in the treatment of both cancerous and non-cancerous diseases of the aforementioned areas.

Do I Need to See Any Other Doctors or Health Professionals for Colon Cancer?

Depending on your treatment, your colon cancer team could consist of a(n):

  • Gastroenterologist: Specialist in the study of the stomach and intestines.
  • Oncologic Surgeon: Well-versed in the treatment of cancer with surgery.
  • Colorectal Surgeon: Well-versed in the treatment of diseases of the colon, rectum, and anus.
  • Radiation Oncologist: Treats cancer with radiation.
  • Medical Oncologist: Treats cancer with medicines such as chemotherapy, targeted therapy, or immunotherapy

Additionally, health care professionals such as physician assistants, nurse practitioners, nurses, psychologists, nutritionists/dieticians, and social workers may be a part of your health care team.


Despite colon cancer being the third leading cause of cancer-related deaths, it is highly treatable when caught early in many cases. One of the main determinants of your prognosis is the stage of cancer, which to a certain extent also determines your treatment plan.

When treated at an early stage, colon cancer has a significant five-year survival rate. If colon cancer does not reoccur within five years, doctors consider you cured.

art4stock / Shutterstock

Nov 14, 2019