What is Colon (Colorectal) Cancer?

Polyps developing from the cellular lining that covers the inner surface of the large intestine undergo transformation and form colon and rectal cancer masses.

What is a Polyp?

Polyps are mushroom-like protrusions formed as a result of the unhealthy and irregular growth, division, and proliferation of the cells covering the inner surface of the large intestine. Over time, they may transform into cancer, penetrating the deeper layers of the colon wall and surrounding blood vessels, and spreading to other organs of the body.

What Causes Colorectal Cancer?

The exact causes of colorectal cancer are not fully known; however, it is considered that the disease arises from both hereditary and lifestyle factors. Lifestyle factors such as smoking, lack of physical exercise, and obesity may increase the risk of developing the disease. Genetic factors determine a person’s predisposition to the disease, while dietary and lifestyle factors influence which individuals at risk will actually develop it. Often, no specific cause can be identified, and it is accepted that the accumulation of random genetic changes in the cells lining the colon and rectum leads to cancer transformation.

Why is it Important?

Colon and rectal cancers are the second most common cause of cancer-related deaths in both men and women. Among all diagnosed cancer patients in our country, colorectal cancers rank third for both men and women. The general risk in the population is 5%, while the risk rises to 10–15% in those with a family history of colorectal cancer. For patients with ulcerative colitis and those with specific genetic mutations in family members, the risk exceeds 50%.

In the United States, colorectal cancers have surpassed breast and prostate cancers in cancer-related deaths and now rank second only to lung cancer.

What Are the Symptoms?

Colon cancer is a silent disease and may often cause no symptoms.

  • Blood in the stool

  • Anemia (iron deficiency)

  • Changes in bowel habits

  • Thinning of the stool

  • Abdominal discomfort (gas, bloating, fullness, cramps, etc.)

  • Vomiting

  • Diarrhea, constipation, or a sensation of incomplete evacuation

  • Frequent gas pains

  • Unexplained weight loss

  • Rectal bleeding

  • Persistent fatigue or weakness during previously easy activities

If any of these symptoms persist for more than two weeks, consult your doctor. If bleeding is present, immediate medical evaluation is necessary. Particularly in individuals over the age of 40 with detected iron deficiency, a colonoscopy is recommended. Although these symptoms are not specific to colon cancer, persistent symptoms lasting more than two weeks should be evaluated.

Can It Be Prevented?

YES! Polyp-related colorectal cancer is preventable. The disease develops from benign polyps (mushroom-shaped growths originating from the inner lining of the colon). Removing these polyps before they turn cancerous can prevent cancer development.

A diet low in fat and rich in fruits and vegetables, along with regular exercise, can reduce the risk of developing colon cancer. When detected early, colorectal cancers can be cured in up to 90% of cases. In the United States, it is estimated that screening and early treatment programs can prevent approximately 40,000 deaths each year due to colorectal cancer.

Who Is at Risk?

The risk of developing colon cancer increases with age. All men and women over the age of 50 are equally at risk. Therefore, colorectal cancer screening is recommended for both men and women aged 45 and older. Individuals with a personal or family history of colorectal cancer or polyps are at increased risk.
High-risk individuals should begin screening before the age of 45, including those with a personal or family history of inflammatory bowel disease (Ulcerative Colitis, Crohn’s Disease); colorectal cancer or polyps; or a history of ovarian, endometrial (uterine), or breast cancer.

How Can I Get Screened for Colon Cancer?

Current screening methods include the fecal occult blood test, flexible sigmoidoscopy, double-contrast barium enema, colonoscopy, and digital rectal examination. Among these, colonoscopy has the highest diagnostic accuracy and allows simultaneous removal of polyps, making it the gold standard method.

How Common is Colon Cancer?

According to GLOBOCAN data, colorectal cancer was the third most common cancer (10%) worldwide in 2018 and the second most common cause of cancer-related deaths (9%). Among women over 75, colon and rectal cancers have surpassed breast cancer as a leading cause of cancer-related death.

How Can Colorectal Cancer Be Prevented?

If you are 45 years or older, consult a physician to undergo a colonoscopy for screening. Reduce your intake of animal fats and focus on a diet rich in fruits, vegetables, and fiber. Stay physically active and avoid smoking. Adhering to colon cancer screening programs enables early removal of polyps and prevents cancer development.

THE ROLE OF GENETICS

Genes are inherited from each parent. They determine various physical traits (e.g., eye color) and may predispose individuals to certain diseases. All cancers, especially colon and rectal cancers (CRC), have hereditary components that can increase an individual’s risk. Genes are the underlying reason why CRC and many other diseases occur more frequently in some families. Therefore, it is important to inform your physician about any known cancer cases in your family.

TYPES OF COLON AND RECTAL CANCERS

There are three main subtypes of colorectal cancer, two of which are genetic in origin:

  • Sporadic (random) colorectal cancer: 50–60%

  • Familial colorectal cancer: 30–40%

  • Hereditary colorectal cancer: 4–6%

Sporadic Colorectal Cancer
This is the most common subtype. Ninety percent of patients are diagnosed at age 50 or older. It is not directly linked to family history or genetic predisposition. When a family member is diagnosed with colon cancer for the first time, it is recommended that other close relatives begin screening earlier (at age 40).

Familial Colon Cancer
Some families are predisposed to developing colon cancer. The risk is higher when two or more relatives are diagnosed with colorectal cancer, especially before age 50. First-degree relatives (parent, sibling, or child) of a person diagnosed with colorectal cancer have double the risk compared to the general population.

For those with a close relative diagnosed with colorectal cancer or polyps, colonoscopy screening should begin at age 40 or 10 years earlier than the age at which the relative was diagnosed. If results are normal, colonoscopy should be repeated every 5 years.

Hereditary Colon Cancer
Hereditary colorectal cancers develop due to the transmission of specific genetic mutations. The syndromes known to cause hereditary colon cancer include:

  • Hereditary Non-Polyposis Colorectal Cancer (HNPCC) – Lynch Syndrome

  • Familial Adenomatous Polyposis (FAP)

  • Attenuated Familial Adenomatous Polyposis (AFAP)

  • Peutz-Jeghers Syndrome

  • MYH-Associated Polyposis (FAP)

  • Juvenile Polyposis

  • Hereditary Polyposis

Colon Cancer Treatment

The most effective approach in colon cancer treatment is an individualized plan based on the stage of the disease. When detected early, surgical treatment offers a very high success rate. In appropriate cases, adjuvant treatments such as chemotherapy or radiotherapy may also be applied. A treatment process carried out by an expert multidisciplinary team improves both quality of life and survival. To learn more about colon cancer treatment and the most suitable options for you, contact us. Taking early action greatly affects the success of treatment.

COMMON MISCONCEPTIONS

Myth: There is nothing I can do to prevent colon cancer.
Fact: You can reduce your risk with a low-fat diet rich in fruits and vegetables and regular exercise. Most colorectal cancers develop from polyps. Screening colonoscopies allow for the removal of polyps before they turn cancerous.

Myth: Colon cancer is always fatal.
Fact: When detected early, colon cancer is curable. Ninety-one percent of patients with localized (early-stage) colon or rectal cancer survive beyond five years after diagnosis. However, only 30% of patients are diagnosed at this stage; the remaining 70% seek medical attention after the tumor has spread beyond the colon wall or to other organs.

Myth: Colonoscopy is only necessary for people with symptoms.
Fact: Early-stage colorectal cancer often causes no symptoms; it can only be detected through regular screening. Screening aims to detect hidden cancer in individuals with no complaints. All men and women aged 45 and older without additional risk factors should undergo regular colorectal cancer screening. In high-risk individuals, screening should start earlier depending on the level of risk.

Myth: Only people with a family history of colon cancer develop the disease.
Fact: In 75% of newly diagnosed colorectal cancer cases—apart from being 50 years or older—there are no known individual or familial risk factors.

Myth: Colorectal cancer occurs only in elderly men.
Fact: Colorectal cancer is the second leading cause of cancer-related deaths in both men and women. The risk increases with age, and those who do not undergo screening are often diagnosed at advanced stages.

Myth: Colonoscopy is a difficult and painful procedure.
Fact: Colonoscopy is not painful. Patients are sedated for comfort during the procedure. The bowel preparation the day before is often feared unnecessarily. Spending a bit more time in the restroom the day before ensures that the entire colon can be thoroughly examined, reducing the chance of missing any lesions. Inadequate preparation may require repeating the colonoscopy.

Myth: Having a polyp means I already have cancer and need surgery.
Fact: Polyps are precancerous lesions that can develop into cancer. If detected early, they can be removed before this transformation occurs, preventing colon cancer. Colonoscopy thus reduces deaths caused by colon cancer. Most benign polyps are removed during colonoscopy. Larger ones can also be removed endoscopically by an experienced physician. Rarely, cancer cells may be found in removed polyps, and surgery may be necessary—but even then, the detected cancer is usually at an early stage. Today, laparoscopic or robotic surgery allows colon and rectal operations to be performed successfully without the need for open surgery.