Colorectal Cancer: What Is It?

Colorectal cancer (CRC), also known as bowel cancer, colon cancer or rectal cancer, is the development of cancer from the colon or rectum.

The colon or large intestine is the final part of the digestive tract and Rectum is the last several inches of the large intestine, closest to the anus.

The colon extracts water and salts from solid waste before they are removed from the body and is the site in which flora aided(largely bacterial) fermentation of unabsorbed material occur.

Colorectal Cancer is the growth of abnormal cells in the lining of the large intestine (also called the colon) or the rectum.

Cause & Risk factors associated with Colorectal Cancer

Colorectal cancer happens when there is a growth of abnormal cells in the lining of the large intestine (also called the colon) or the rectum. It can strike both men and women.

The growths on the inside of your intestines, most of them being harmless, but some can turn into colorectal cancer if not removed early.

Most colorectal cancers are due to old age and lifestyle factors, with only a small number of cases due to underlying genetic disorders.

There are certain risk factors associated with it, which increases the chance of occurrence of Colorectal Cancer.

Risk Factors You Can't Control

Some things you just canʼt help, such as:

  • Your age -- most people with it are older than 50
  • Polyps or inflammatory bowel disease
  • Family history of colorectal cancer or precancerous colon polyps

Risk Factors You Can Control

Try to avoid these things that can raise your odds of getting the disease:

  • Eating a lot of red or processed meats, or those cooked at high temperatures
  • Obesity (having too much fat around the waist)
  • Not exercising enough
  • Smoking
  • Heavy alcohol use

What Are the Symptoms?

Symptoms may not appear until a later stage, but if they do, gastrointestinal problems are common symptoms.

They include:

  • diarrhea or constipation
  • changes in stool consistency
  • loose and narrow stools
  • rectal bleeding or blood in the stool
  • abdominal pain, cramps, bloating, or gas
  • pain during bowel movements
  • continual urges to defecate
  • weakness and fatigue
  • unexplained weight loss
  • irritable bowel syndrome (IBS)
  • iron deficiency anemia

If the cancer spreads to a new location in the body, additional symptoms can appear in the new area. The liver is most commonly affected.


Tests That Find Colorectal Cancer: Screening tests are key to an early diagnosis.They are -

Colonoscopy & Sigmoidoscopy

What Is a Colonoscopy?

Itʼs a test of your colon and rectum. This test uses a tube with a tiny camera to look at the whole colon and rectum. It can help prevent colorectal cancer by finding tumors early.Your doctor will then remove the polyps. One should have a colonoscopy every 10 years once they turn 45yrs.

What Is a Sigmoidoscopy?

It is a procedure that lets your doctor look inside your sigmoid colon by using a flexible tube with a light on it


If a test shows a possible tumor, the next step is a biopsy. During the colonoscopy, your doctor takes out polyps and gets tissue samples from any parts of the colon that look suspicious.

Fecal Blood Tests

The test show whether you have blood in your stool, which can be a sign of cancer.

Medical imaging

A colorectal cancer is sometimes initially discovered on CT Scan. Imaging tests such as PET and MRI may be used in certain cases.

Blood testing

Your doctor may run some blood tests to get a better idea of whatʼs causing your symptoms. Liver function Test (LFT) and Complete Blood Count (CBC) can rule out other diseases and disorders.

The Stages of Colorectal Cancer

Experts "stage" any cancers they find -- a process to see how far the disease has spread. Higher stages mean you have a more serious case of cancer. Tumor size doesnʼt always make a difference. Staging also helps your doctor decide what type of treatment you get.

  • Stage 0: Cancer is in the innermost lining of the colon or rectum.
  • Stage I: The disease has grown into the muscle layer of the colon or rectum.
  • Stage II: Cancer has grown into or through the outermost layer of the colon or rectum.
  • Stage III: It has spread to one or more lymph nodes in the area.
  • Stage IV: It has spread to other parts of the body, such as the liver, lungs, or bones.

How can you Prevent Colorectal Cancer?

  • Healthy Diet-Eat a nutritious diet and control your body fat.
  • Exercise-getting 150 minutes per week of moderate exercise, like brisk walking, or 75 minutes per week of vigorous exercise, like jogging.
  • Screening-screening for this cancer is effective for both early detection and for prevention.Any polyps that are detected can be removed, usually by colonoscopy or sigmoidoscopy and thus prevent them from turning into cancer. Screening has the potential to reduce colorectal cancer deaths by 60%


The treatment of colorectal cancer can be aimed at cure or palliation. The decision on which aim to adopt depends on various factors, including the patientʼs age, health and preferences, as well as the stage of the tumor.

  • At early stage- surgery can be curative.
  • Later stages (for which metastases are present)- treatment is often directed at palliation, to relieve symptoms caused by the tumour and keep the person as comfortable as possible.


  • If the cancer is found at a very early stage, it may be removed during a colonoscopy using a variety of techniques including EMR or Endoscopic mucosal resection and ESD or Endoscopic submucosal dissection . For people with localized cancer, the preferred treatment is complete surgical removal with adequate margins.
  • ColectomySurgery to remove part or all of the colon is called a colectomy. The surgeon removes the part of the colon containing the cancer and the surrounding area. Nearby lymph nodes are also usually removed. The healthy portion of the colon will either be reattached to the rectum or attached to a stoma depending on the extent of the colectomy. A stoma is an opening made in the wall of the abdomen. Waste will pass into a bag, removing the need for the lower part of the colon. This is called a colostomy.
  • Some small, localized cancers can be removed using endoscopy. Laparoscopic surgery, using several small incisions in the abdomen, may be an option to remove larger polyps. Palliative surgery may relieve symptoms in cases of untreatable or advanced cancers. The aim is to relieve any blockage of the colon and manage pain, bleeding, and other symptoms.


In both cancer of the colon and rectum, chemotherapy may be used in addition to surgery in certain cases. The decision to add chemotherapy in management of colon and rectal cancer depends on the stage of the disease.

Chemotherapy administers chemicals that interfere with the cell division process by damaging proteins or DNA in order to damage and kill cancer cells. These treatments target any rapidly dividing cells, including healthy ones. The healthy cells can usually recover from any chemically-induced damage, but cancer cells cannot.

Chemotherapy is generally used to treat cancer that has spread because the medicines travel through the whole body. Treatment occurs in cycles, so the body has time to heal between doses.

Common side effects include:

  • hair loss
  • nausea
  • fatigue
  • vomiting

Radiation Therapy

Radiation treatment damages and kills cancer cells by focusing high-energy gamma-rays on them.

Radioactive gamma-rays are emitted from metals such as radium, or from highenergy xrays. Radiotherapy can be used as a standalone treatment to shrink a tumor or destroy cancer cells, or alongside other cancer treatments. Radiation treatments are not often used until a later stage. They may be employed if early stage rectal cancer has penetrated the wall of the rectum or traveled to nearby lymph nodes. Side effects may include:

  • mild skin changes resembling sunburn or suntan
  • nausea
  • vomiting
  • diarrhea
  • fatigue
  • appetite and weight loss

Most side effects resolve a few weeks after completing treatment.

Palliative Care

Palliative care is recommended for those who has advanced colon cancer or who has significant symptoms.

It can be beneficial to improve the quality of life for both the person and his or her family, by improving symptoms, anxiety and preventing admissions to the hospital.

In people with incurable colorectal cancer, palliative care can consist of procedures that relieve symptoms or complications from the cancer but do not attempt to cure the underlying cancer, thereby improving quality of life.


When discovered early, colon cancer is highly treatable .Up to 90 percent of patients whose colorectal cancer is diagnosed and treated in the early stages can be cured.

  • Dr. Ronak Malani

    Gastroenterologist & Colorectal Cancer Specialist