Colon and Rectal Cancer

Colon and Rectal Cancer

Do you know in the recent decade more young people have developed colon and rectal cancer? According to studies, millennials have double the risk of colon and four times more risk of rectal cancer when compared to people born in the 1950s. This trend has raised several questions about the lifestyle, environmental factors, and screening techniques for colorectal cancer (CRC). Till now, it is not clear why people, especially younger than 50 years get CRC. Keeping these facts in mind, the biggest focus is on preventing, detecting and treating CRC as early as possible.

Colon and Rectal Cancer

Colon and rectal cancers are abnormal growths in the colon and the rectum (parts of the lower region of the digestive system). These cancers have many common features, so they are usually grouped as colorectal cancer.

Colorectal cancer is the third most common cancer in men and the second most common in women, globally. (1) In India, colon cancer is the eighth most common in men and ninth most common in women, whereas rectal cancer is in the ninth position in men and it doesn’t figure in the top 10 cancer in women. (2)

According to World Health Organisation, about 36,687 men and 20,064 women were newly diagnosed with colorectal cancer in 2018. Also, 20,056 people died of rectal cancer and 19,548 died of colon cancer.

Colorectal Cancer Causes and Risk Factors

Colorectal cancer occurs when the cells lining the colon or the rectum begin to grow and divide abnormally, resulting in the formation of a mass of tissue, known as a polyp. Not all polyps are cancerous, only some that continue to grow may become cancerous. The cancerous cells in the polyps may invade the other tissues and lymph nodes and metastasize to distant parts of the body.

The exact cause of colorectal cancer is not yet unknown. However, the following may increase the risk factors for colorectal cancer:

Non-modifiable risk factors:

  • Age
  • Family history
  • Personal medical history
  • Inherited syndromes

Modifiable Risk Factors:

  • Diet rich in refined and processed foods
  • Physical inactivity
  • Smoking
  • Alcohol consumption

Signs and symptoms of colorectal cancer:

CRC usually doesn’t cause any signs or symptoms immediately. But, if it does, then it might cause the following:

  • Incomplete bowel emptying
  • Narrower stools than usual
  • Loose stools or constipation
  • Blood in stools or rectal bleeding
  • Abdominal pain/ cramps
  • Bloating
  • Frequent flatulence
  • Tiredness

 Visit a doctor immediately, if these symptoms persist for more than two weeks.

Screening for CRC:

Regular screening is the only way to detect and beat CRC during the early stages. According to recent American Cancer Society guidelines, a person with an average risk of CRC must begin screening at 45 years and proceed until 75 years. After the first screening, the person is advised to have a screening every ten years.

People with a high risk of CRC must start screening before the age of 45 and should get screened more often.

Colorectal Cancer Diagnosis:

Diagnosing CRC during the early stages improves the survival rate to about 90%. Initially, the patient’s history, including the information about the incidence of symptoms, family history of CRC or polyps, and personal medical history is collected. Later, a physical examination and a digital rectal examination are done.

Physical examination: It is performed to examine the abdomen and other parts of the body to detect any enlarged organs or abnormal masses.

Digital rectal examination: It is performed by inserting a lubricated, gloved finger in the rectum to detect the presence of any abnormal masses.

If the doctor suspects colorectal cancer then the following diagnostic tests are recommended:

Colonoscopy: It is performed both as a screening and confirmatory test for CRC. This test involves the insertion of a colonoscope (a thin, long, tube-like instrument with a light, outlet for air, and camera) into the colon and the rectum to view any abnormalities.

CT Colonography: A colonoscope is inserted into the patient’s colon and the air is passed to inflate the colon. The patient is now passed through the CT scanner, which takes multiple and detailed images of the colon and the rectum.

Stool tests: Stool samples are collected and examined to determine any abnormal signs of colorectal cancer. Faecal immunochemical test (FIT) or Immunochemical faecal occult blood test (iFOBT), Guaiac-based faecal occult blood test (gFOBT), and stool DNA test are some stool tests employed for diagnosing CRC.

Flexible Sigmoidoscopy: In this test, a sigmoidoscope (a thin, flexible, lighted tube fitted with a video camera) is inserted into the rectum and passed to the lower part of the colon to detect polyps or cancer.

Biopsy: If abnormalities are found in any of the diagnostic tests, a biopsy is advised. In this test, special surgical tools are passed inside the colon or rectum to collect a tissue sample. This tissue is further examined in the laboratory.

Blood test: People with CRC may experience bleeding that may result in anaemia. Additionally, it helps in determining the health of the kidney and the liver. A blood test might also be done to detect the presence of a chemical known as carcinoembryonic antigen, which might indicate CRC.

Staging of CRC:

Staging of cancer helps to know about the severity, size, extent and spread of cancer. The stage of CRC are as follows:

  • Stage I: Cancer has grown through the inner lining and entered into the muscular layer of the colon or rectum.
  • Stage IIA: Cancer has grown into the colorectal wall.
  • Stage IIB: Cancer has grown through the muscular layer of the colon and the rectum and extended to the lining of the abdomen.
  • Stage IIC: The tumour has spread through the colon or rectal walls and has invaded nearby structures.
  • Stage IIIA: Cancer has grown through the walls of the colon or rectum. It has spread to 1 to 3 lymph nodes or forms a tumour nodule in tissues around the colon or rectum.
  • Stage IIIB: Cancer has grown through the wall of the colon/ rectum or to surrounding organs. It has spread to 1 to 3 lymph nodes or forms a nodule of tumour in tissues around the colon or rectum that do not appear to be lymph nodes.
  • Stage IIIC: Cancer has grown through the wall of the colon/ rectum. It has spread to 4 or more lymph nodes.
  • Stage IV: Cancer has spread to distant parts of the body.


Colorectal cancer treatment depends on the location and stage of cancer. Also, the patient’s age, medical history, and overall health condition are considered.

Treatment modalities for CRC include:

Colorectal Cancer Surgery:

Surgery is the common treatment option for all stages of CRC. Surgery is done to remove the tumours and surrounding tissues where cancer might have spread. Depending on the location and stage of cancer the doctor might recommend any of the following surgeries:

Colon cancer surgeries:

  • Polypectomy
  • Open colectomy
  • Laparoscopic colectomy
  • Colon obstruction surgery
  • Colostomy

Rectal cancer surgeries:

  • Local resection
  • Total mesenteric excision
  • Pelvic exenteration


Chemotherapy is the use of drugs to kill cancer cells. It is either given orally or in the form of an intravenous injection. Chemotherapy is usually given after the surgery to prevent the recurrence of cancer or before the surgery to shrink the tumour.

Radiation therapy:

It involves the usage of high-energy beams to shrink and destroy cancer cells. Radiation therapy is usually combined with surgery/chemotherapy. For colorectal cancer, radiotherapy is usually used to target rectal cancers than colon cancers.

Targeted therapy:

It involves the administration of certain medicines to block the growth and spread of cancer cells. Targeted therapy acts by inhibiting the action of specific molecules, enzymes, or proteins that are responsible for the growth and progression of cancer.


Immunotherapy boosts the body’s natural defence system against cancer. It involves the use of substances derived or made from living organisms. Immunotherapy acts by recognizing and attacking cancer cells or by boosting the function of immune cells.

Prevention of Colorectal Cancer

Cancer prevention has always been a top objective, but the promise of cancer prevention remains unfulfilled. However, there are a few approaches that help in lowering the risk of colorectal cancer. These include:

  • Getting screened regularly
  • Maintaining a healthy body weight
  • Exercising regularly
  • Eating a healthy diet
  • Avoiding alcohol consumption
  • Smoking cessation


Recent evidence has changed our understanding of cancer, its biology, and the complex interaction of risk factors. The desired actions are always clear and simple to state, but execution always remains a formidable challenge. One can overcome this, by moving beyond the challenges and taking necessary actions to reduce the global burden of cancer.

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