What is Colorectal Cancer and Can I Prevent It?

Colorectal cancer develops when cells in the colon, rectum, or both begin to multiply uncontrollably. If left untreated, colorectal cancer may spread to other parts of the body.

Colorectal cancer is the fourth-most commonly diagnosed and second-most deadly form of cancer in the United States. The average age of diagnosis for colorectal cancer is 66, with African Americans having a 35% higher mortality rate. The good news, however, is that it is preventable and curable with early detection.

The colon is a muscular tube that is, on average, five feet long. It is also known as the large intestine. It receives the waste products from the food digested in the small intestine. The main job of the colon is to absorb water and electrolytes from the waste. The rectum, which is the last several inches of the large intestine, receives and holds the waste matter, or stool, until it can be passed as a bowel movement.

Growths in the inner lining of the colon or rectum are called polyps. Polyps are usually the precursors of colon cancer or rectal cancer.  However, not all polyps turn into cancer. A polyp is more likely to become cancerous if:

  • It is larger than 1 cm.
  • It has dysplasia, or abnormal cells. This can be determined after the polyp is removed and examined.

The colon and rectal walls consist of multiple layers. Colorectal cancer starts in the mucosa, the innermost layer, and spreads to the other layers. It can also spread to nearby lymph nodes and to distant parts of the body if left undetected and untreated.

Risk Factors for Colorectal Cancer

Several factors increase a person’s risk of getting colorectal cancer, including:

  • Family history and genetic factors. A family history of the disease raises the risk. Inherited syndromes such as familial adenomatous polyposis and Lynch syndrome also increase the risk.
  • Personal history of colorectal cancer or polyps.
  • Age. Risk increases with age.
  • Race. In the US, African Americans have the highest colorectal cancer risk.
  • Inflammatory bowel diseases. Inflammatory bowel illnesses, like ulcerative colitis and Crohn’s disease, raise the risk.
  • Low-fiber, high-fat diet.
  • Not exercising regularly.
  • Diabetes.
  • Obesity.
  • Smoking.
  • Drinking alcohol.
  • Radiation therapy for cancer. Radiation treatment in the abdomen for cancer raises colorectal cancer risk


Polyps in the colon do not always produce recognizable symptoms. This can cause colorectal cancer to go undetected for extended periods. Eventually, warning signs may begin to occur, including:

  • Changes in bowel habits
  • Blood in the stool or rectal bleeding
  • New or worsening abdominal pain
  • A sense that bowel movements are not complete
  • Fatigue or weakness
  • Unintentional weight loss

Prevention and Early Detection

The American Cancer Society says regular screening can prevent colorectal cancer because polyps can take 10 to 15 years to develop into cancer. Early-stage colorectal cancer has a five-year survival rate of 90%. However, roughly 60% of colorectal malignancies get beyond that stage.  The CDC says screening for colorectal cancer should begin at age 45 and continue at regular intervals. It should ideally start at age 40 for African Americans.

Types of Colorectal Cancer Screening Tests

With proper screening, it is possible to identify and treat precancerous polyps before they become cancerous.


There are three types of stool tests available for cancer screening: gFOBT, FIT, and stool FIT-DNA.

  • The gFOBT, guaiac-based fecal occult blood test, is a once-a-year, at-home test. A patient sends a small stool sample to a doctor who checks it for the presence of blood using the chemical guaiac. This test is the least specific of the three stool-based tests and is not highly recommended by most gastroenterologists.
  • The FIT, fecal immunochemical test, works the same way, except it uses antibodies to check for blood in the stool. This also is an annual test.
  • A FIT-DNA test requires the collection of an entire bowel movement that the patient sends to a doctor. The doctor then checks the stool for blood and altered DNA. Experts recommend this test every three years

It is important to mention that if any of these tests are positive, colonoscopy is recommended so that any polyps present can be removed.


Visual tests for colorectal cancer screening involve more preparation and are more invasive. These tests include:

  • Colonoscopy: This test involves a physician using a thin, flexible tube that is attached to a video camera and monitor to view the full length of the colon and rectum. The tube also can be equipped with surgical tools so the doctor can take tissue samples and remove polyps. It may be done every 10 years or more frequently for people with an increased risk for colorectal cancer.
  • CT colonography: A physician inserts a small tube into the anus and pumps air into the rectum and colon followed by performing X-rays to check for polyps. If polyps are seen, a colonoscopy should then be performed to remove them.
  • Flexible sigmoidoscopy: This is similar to a colonoscopy, however the physician only views the rectum and sigmoid colon.


Biopsies help doctors confirm suspected cases of colorectal cancer. Your doctor will use a colonoscope to extract a tiny tissue sample which is sent to the lab for testing. If the biopsy confirms the presence of cancer, doctors may perform other tests to classify the cancer and form treatment plans.

Maintaining a Healthy Lifestyle for Prevention

To help aid in the prevention of colorectal cancer, it is important to:

  • Avoid red and processed meats while following a diet that is high in fruits, vegetables, and whole grains.
  • Avoid alcohol when possible and drink in moderation.
  • Avoid smoking and other forms of tobacco.
  • Maintain a healthy weight by exercising regularly and eating healthy foods.

Treatment Options for Colorectal Cancer

Colorectal cancer has five stages, and the treatments change with each one. Most patients will need to see a surgeon and/or an oncologist (cancer doctor) after being diagnosed with colorectal cancer.

During stage 0 and stage 1, the cancer has not spread beyond the colon wall or into nearby lymph nodes. Surgery is generally all that is necessary in the early stages, but it may be paired with other treatments in later stages, including chemotherapy, radiation therapy, and immunotherapy.

Improving Your Odds

People age 45 and older should prioritize colorectal cancer screenings to help prevent the disease. Early detection also gives patients more treatment choices.

At the Florida Medical Clinic, our gastroenterologists can help you choose the correct screening method for you. Our on-site pathology reduces diagnostic and treatment time while our sophisticated electronic records system allows seamless communication with your doctors.

Meet Dr. Cassandra Gandle

Dr. Cassandra Gandle earned a Bachelor of Arts degree in Biology and a Bachelor of Arts in Art History in 2013 at Johns Hopkins University. She completed her medical school at Tulane University School of Medicine. She completed her residency and gastroenterology fellowship at the Baylor College of Medicine in Houston, Texas.

Dr. Gandle was born and raised in the Tampa area and returned to Florida to become a part of the Florida Medical Clinic’s Gastroenterology team, where she provides evidence-based care to each patient. Outside of her medical career, Dr. Gandle enjoys health and fitness and art history.



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