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Colon Cancer

Colon Cancer

General Promotion

Colon and rectal cancers are mostly caused by polyps in these areas. About one million people worldwide are diagnosed with colon and rectal cancer each year. The disease is very important because it is one of the types of cancer that causes the most loss of life.

Another name for cancer of the large intestine or colon and rectum (CRC); is colorectal cancer. The lifetime probability of developing CRC is slightly higher in men than in women. This rate; 4.5 percent for men and 3.2 percent for women. CRC mostly develops from adenomas (polyps).

These benign tumors originating from the colon or rectal mucosa often go undetected because they remain silent for many years. The incidence of adenomas increases with age. However, although the process of cancer development from adenoma has been largely clarified, the external factors affecting this process are still being discussed.

Colon and Rectum Cancer (CRC) Prevention Ways

The main condition for protection from colon and rectum cancers is not to neglect the necessary screening tests. It is the primary way to prevent colon cancer to have occult blood in the stool, colonoscopy or sigmoidoscopy tests as recommended by your physician who evaluated your family history and medical history.

On the other hand, avoiding cigarettes, tobacco products, and alcohol, adopting an active lifestyle in terms of sports and exercise, not overconsumption of fat and red meat, and adopting a diet rich in whole grains and fiber foods are also protective against colon cancer.

What is Colon Cancer? How frequent is it in Turkey?

Cancers that occur on the inner surface of the large intestine, which is about 1.5 meters long, are called colon cancer. This type of cancer occurs with the uncontrolled growth of cells and cell communities in the layer that covers the inner surface of the large intestine.

The last 15-20 cm of the large intestine is called the rectum, and the cancers that appear here are called rectal cancer. “Colorectal cancers” is also a very common term to describe two types of cancer.

According to the data of the Ministry of Health, colorectal cancers are among the top 5 most common cancers in our country.

Are There Risk Factors Like Age, Gender, Having Bowel Diseases?


Colon cancer can occur at any age. The average age of onset is 63. However, according to studies, one-third of patients diagnosed with colorectal cancer are younger than 55 years of age.


There is no difference in incidence between men and women.

Other Risk Factors

Although the exact cause of colorectal cancer is not known, the risk factors that increase the development of colorectal cancer are as follows:

  • Advanced age,
  • Presence of polyps in the intestine (especially those with adenomatous pathology),
  • Presence of colorectal cancer patients in the family
  • Presence of certain genetic disorders (patients with non-hereditary polyposis colon cancer) and/or familial polyposis syndromes characterized by hereditary polyps in the colon and rectum, which have caused significant changes in genes,
  • Presence of inflammatory bowel disease (Ulcerative colitis or Crohn's disease) that may cause cancer by disrupting the intra-intestinal cell type within a certain period of time,
  • Having a history of ovarian, breast and uterine cancer in women
  • Excessive consumption of processed and animal foods, less consumption of fruits and vegetables and smoking,

People with these risk factors should be screened for bowel cancer from an earlier age.

What are Colon Cancer Symptoms?

The onset of colon cancers is cell growths in the intestine, namely polyps. However, polyps often do not cause any complaints at first. As polyps begin to become cancerous, grow in size, or increase in number, they cause the following changes in a person's bowel habits:

  • New onset constipation or vice versa, change in stool consistency (in favor of diarrhea) or odor,
  • Anemia caused by iron deficiency,
  • Thinning of the thickness of the stool, blood mixed with the stool or bleeding from the anus after going to the toilet,
  • Abdominal pain, loss of appetite and involuntary weight loss.


The above findings alone do not indicate colorectal cancer. However, if you have these complaints, you should definitely consult your doctor for the necessary controls. In addition, if you have a family history of bowel cancer, breast, ovarian or cervical cancer along with one of these symptoms, do not neglect to consult your doctor.

Can These Symptoms Also Occur due to Hemorrhoids or Changes in the Bowel?

Bleeding from the rectum can also be seen due to hemorrhoid disease or anal fissures rather than colorectal cancer symptoms, especially in young people, those with chronic constipation, those who do not have alarm complaints (such as weight loss, loss of appetite, anemia). It is often not possible to tell the true cause of these complaints without further investigations.

Does Ulcerative Colitis Cause Colon Cancer?

Ulcerative colitis or Crohn's disease is chronic inflammation of the tissues lining the large intestine. Both are risk factors for developing colorectal cancer disease.

Especially in people who have had ulcerative colitis for more than 10 years (even if they have responded to treatment), the probability of developing colorectal cancer is considerably increased. For this reason, routine screening colonoscopies should be performed in these patients whether or not they have complaints related to their disease.

In Crohn's disease, the probability of developing colorectal cancer increases in areas with intestinal strictures due to this disease. Continuing to smoke definitely increases the risk of developing colorectal cancer in the presence of these two diseases.

What Tests Are Used for Early Diagnosis of Colon Cancer?

Tests for early screening of colon cancer include:

  • Colonoscopy,
  • Checking for occult blood in the stool,
  • Computed tomography (CT) colonography
  • Flexible sigmoidoscopy,
  • DNA tests in stool.

What is Colonoscopy Procedure?

Colonoscopy is to enter the large intestine, which has previously been cleaned of stool, through the anus, with an instrument with a light and camera at the end, and inflate the intestine slightly by giving air and examine the inside of the intestine. It usually takes about 30-45 minutes.

If deemed necessary during the procedure, biopsies can also be taken from the mucosal covering of the intestine and tissues with abnormal appearance. If polyps are seen, they can be removed in the same session. Existing bleeding foci can also be stopped during colonoscopy. Procedures such as colonoscopy can be approached with reservations.

Is This Procedure Painful and Painful?

Colonoscopy can be performed by giving pain-reducing drugs or by making the person light sleep in the presence of an anesthesiologist. For this reason, colonoscopy is definitely not a painful procedure as it is thought and feared.

The most tedious part of the colonoscopy procedure is the cleansing of the intestine by feeding with various drugs and plenty of watery foods the day before colonoscopy (preparation for colonoscopy). This preparation process and the method of performing the procedure are explained in detail by the physician/nurse/health personnel before the procedure, and the fears of the patients can be reduced.

How Often Should Colonoscopy Be Repeated?

Colonoscopy screening is started at the age of 50 in people who do not have a family history of bowel cancer and have no bowel complaints, and should be repeated every 10 years in the absence of any polyps.

For people with a first-degree relative with bowel cancer or breast, uterine and ovarian cancers before the age of 65, the age of screening with colonoscopy is 40 years. If the age of 1st degree relative of the person is 10 years before the age of 40, it should be screened at an early age.

In patients with ulcerative colitis, colonoscopy control is required every year when the disease age exceeds 10 years.

In people with genetically inherited polypoisis syndromes in the family, screening should begin at the age of 15-18 years.

Depending on the number and pathological types of polyps detected in screening colonoscopy, control colonoscopy is performed at intervals of 1-3-5 or 10 years. If screening is aimed only for left colon tumors, flexible sigmoidoscopy every 2-3 years can be used for screening between long colonoscopic examinations.

Unless there are necessary conditions, the statements that "colonoscopy should be done every year" are not true.

In cases where the patient does not prefer colonoscopy, CT colonographies can be performed every 5 years. However, only diagnosis can be made in CT colonographs, when any polyp or mass is seen, colonoscopy will be required to take a biopsy from those lesions.

Testing for occult blood in the stool should be done once a year until the first colonoscopy screening. DNA tests in the stool are also among the screening tests performed every 2-3 years.

What Should Be Considered To Protect From Colon Cancer?

In order to be protected from colon cancer, it is necessary to eat healthy and to have screening tests at the right time intervals within the specified recommendations.

A diet rich in vegetables, fruits and fiber, avoiding processed and animal protein-based foods, regular exercise, and not smoking are the methods of protection from bowel cancer.


Colon and rectal cancer symptoms include blood in the stool, change in stool habits in the form of diarrhea or constipation, thinning of the stool like a pencil, frequent need to go to the toilet but insufficient defecation, intermittent, sometimes colic-like abdominal pain and bloating, pallor due to occult blood loss, mucus in the stool , weakness, weakness, feeling of mass in the abdomen.

Colon And Rectum Cancer (CRC) Risk Factors

The main known risk factors for the formation of colon and rectal cancers are:

  • Advanced age
  • Male gender
  • Presence of colon cancer in the family,
  • The person has previously had cancer of the large intestine, breast, ovary or uterus,
  • Presence of polyps in the colon,
  • Presence of a chronic inflammatory bowel disease such as ulcerative colitis or Crohn's disease,
  • Environmental factors: Frequent consumption of animal fat and red meat (especially beef, pork and lamb), diet low in fiber (fiber), obesity, excessive caloric intake and low physical activity, excessive smoking and alcohol consumption.

Diagnostic Methods

After consulting your family and medical history, your doctor will perform a physical examination and request some tests if she suspects colorectal cancer.

Diagnosis of colorectal cancers The diagnosis of colorectal cancers is first made by evaluating the samples taken during endoscopic examinations (colonoscopy, rectoscopy, sigmoidoscopy, virtual colonoscopy) in the pathology laboratory. After the diagnosis of cancer is finalized, imaging methods are used in the evaluation of the disease and determining the stage of the disease.

Chest X-ray, abdominal computed tomography (CT), ultrasonography (US), magnetic resonance imaging (MR), endorectal ultrasonography (ERUS), positron emission tomography (PET) are the examinations requested according to the characteristics of the patient and the tumor. As a result of this evaluation, the stage of the disease is determined and treatment is planned.

In addition, blood tests such as complete blood count and biochemical tests are used to determine the course of the disease and other possible effects on the body. CEA (carcinoembryonic antigen), one of these blood tests, is an increasing marker in colon cancers and can be used in the diagnosis and follow-up of the disease.

Treatment Methods

Colon and rectal cancers are treated with various methods. Surgery, chemotherapy (drug therapy) and radiotherapy (radiation therapy) are the most commonly used treatments.

It is important to obtain information about the general condition of the patient and the prevalence of the disease before making a treatment plan for colon and rectal cancer. For this reason, it is necessary to know in which stage of CRC it is in the treatment.

Colon and Rectum Cancer Classified in 4 Stages

Stage I: It is the earliest disease stage. Cancer cells occupy the inner and middle layers of the intestine. There is no involvement in lymph nodes and distant organs.

Stage II: Cancer cells occupy all layers of the intestine, reach the outermost layer, and can spread to neighboring organs or organs. There is no involvement in lymph nodes and distant organs.

Stage III: Regardless of the level of involvement in the intestinal wall, there is tumor spread in the lymph nodes adjacent to the intestine.

Stage IV:  It constitutes the most advanced stage of the disease. Regardless of the tumor spread in the intestinal wall or lymph nodes, there are metastases in organs such as liver, lung, peritoneum, bone, brain.

The main treatment for colon and rectal cancer at all stages is surgery. However, the type of surgical treatment may change depending on the location, size, stage of the tumor in the colon and rectum, and whether the patient presents with tumor complications (such as obstruction, perforation, bleeding) in emergency conditions.

Today, laparoscopy applications in the surgical treatment of colon and rectum cancer are becoming more and more common. The main techniques used are:

In some small rectal tumors, cutting and removing only the tumor part through the anus is called local excision.

Resection is the removal of a part (or all) of the large intestine and a part (or all) of the rectum, depending on the location of the tumor.

In this surgical technique, the adjacent lymph nodes are removed together with the intestine. If the tumor has spread to neighboring organs, these organs must also be removed during radical surgery. The healthy intestinal ends remaining from the removed intestine are brought together and sutured (anastomosis).

After colon or rectal resections, an artificial anus (ileostomy or colostomy) can be created by suturing the small intestine or colon to the abdominal wall for various reasons. The intestinal contents are emptied from this artificial anus into the plastic bag attached to the abdominal wall. This may be permanent in some patients. However, in some patients, since there is no medical need, the artificial anus is closed, allowing patients to defecate in a normal way.

Appropriate number and size of liver and lung metastases can be surgically removed (metastasectomy).

In advanced stage colon and rectum cancers that cannot benefit from radical surgical treatment, palliative surgical interventions that will increase the patient's comfort of life can be applied (for example, colostomy opening).

III. and IV. Chemotherapy and/or radiotherapy are added to the treatment before and/or after the surgery of the patients in the second stage.

Systemic Treatment of Large Intestine (Colon and Rectum) Cancer

Systemic treatment of colon cancer is in the form of intravenous administration of some drugs. These drugs are chemotherapy drugs and some targeted drugs.

Even if colon cancer is diagnosed at an early stage and completely removed from the body by surgery, some tumor cells can travel to various parts of the body via lymph and blood vessels. Despite all imaging and diagnostic methods, these cells called “micrometastases” may not be detected.

If these cells are not destroyed, they multiply and grow over time, causing the disease to reappear (metastasis) in any part of the body. For this reason, adjuvant chemotherapy is applied after surgery depending on the stage in large bowel cancers.

Targeted drugs are widely used in the treatment of colon cancer. These drugs are used only in stage IV disease, they have no effect in the preventive treatment of early stage disease. Like chemotherapy, they are administered intravenously and are effective throughout the body.

In some studies, it has been shown that when these drugs are used together with chemotherapy, they increase the benefit of chemotherapy by 25-30%. In this way, by reducing the tumor masses in the body, they increase the probability of success of the surgical removal of tumor areas (metastasectomy) from the liver and lung, which is very important in patients with colon cancer and is frequently performed.

It also has positive effects in terms of prolonging lifespan. In addition, these drugs usually do not have side effects similar to chemotherapy such as weakness, fatigue, nausea and vomiting.

It has been found that some newly developed targeted drugs in resistant colon cancers that continue to progress despite the use of many chemotherapy drugs, prolong the life span and slow the course of the disease.