Colorectal Cancer

This article has been written to help patients with colorectal cancer. It will help them to understand the disease and consider the best treatment options for them.

Anatomy of the colon

The small intestine is almost twenty feet in length while the colon is measured about 5 feet in length. The large intestine starts from the cecum and ends at the rectum. The main parts of a colon or large intestine are:

  • The right portion of the colon is called Ascending colon
  • The middle part of the colon is called the Transverse colon
  • The left part of the colon is called Descending colon
  • The lower part of the colon is called the Sigmoid colon

The ascending colon starts from the cecum exactly at the region where the small intestine discharges into the colon. The transverse colon moves at the top of the colon circuit from the left side to the right side. The descending colon moves from the transverse colon to the downside  , sigmoid colon. The rectum and colon are connected by an S-shaped sigmoid colon. The rectum elongates almost eight inches towards the anus. There is a transitional zone present between the keratinized and non-keratinized stratified squamous epithelium cells. The anus is the last part of GIT and is almost 4 to 6 cm long.

All the parts and organs of GIT are in correspondence to ensure the safe intake and defecation of the products. There are billions of bacteria in the lining of the colon that aids in process of reabsorption.

Both nervous systems such as the parasympathetic system and sympathetic system are involved with GIT. They start sending signals and aids in the coordinated symphony movements that help in the movement of contents from GIT to the colon passing through the small intestines. The enzymes released from the pancreas, intestinal glands liver helps in the formation of chyme activate the movements of the food. The churning movements help the food contents to contact with intestinal lining ( villi) from the lumen. There is the release of water and mucus. Mechanical and chemical digestion takes place throughout the GIT.

The contents of the bowel move forward by rhythmic and propulsive movements known as segmentation and peristalsis respectively. These are circular and longitudinal. The contents are moved into the cecum and colon through the peristalsis. Almost 1 liter of illeal contents is stored in the colon every day. The water and electrolytes are removed from the illeal content as it moves through the ascending colon, the contents become more concentrated and a solid form of contents enter the sigmoid colon. Then it moves into the rectum and is finally expelled through the anus.

When the stool comes in contact with rectal walls the process of defecation is stimulated. The anal sphincters are relaxed and the stool is expelled out. Following things can cause dysfunction of the normal rectal and anal control:

  • Tumors
  • Blockage
  • Nerve damage

Colorectal cancer

If there is an increased production of cells in the lining of the colon and colon lumen then this condition is called colorectal cancer. The extra cells continue to divide without any restrictions and turn into a tumor. These cells have no proper shape and orientation. If they come in contact with the healthy cells they can destroy them too. The tumors are painless and they keep growing inside the body until they become very large. Tumor cells can be poorly, moderately, or well-differentiated.

If there is a growth or bumps present on the epithelial mucosa at the intestinal lining the condition is referred to as adenomatous polyp. This adenomatous polyp is a reason for almost 95% of cancer cases. Polyps may be:

  • Cancerous
  • Raised
  • Flat
  • Benign
  • Precancerous

A polyp leads to severe conditions such as dysplasia, carcinoma in situ cancer, and metastasis. If the polyps are removed earlier then it will save a patient from severe conditions.


Some risk factors enhance the chances for a patient to develop colorectal cancer. These are:

  • Age: People with age 50 or above have higher chances to develop colorectal cancer
  • History: Patients with a history of any polyps, tumors, or surgeries have higher risks of colorectal cancer
  • Heredity
  • Smoking
  • Crohn’s disease or colitis
  • Diet with high fats
  • Red meat
  • Energy drinks
  • Inactive lifestyle

Late signs and symptoms

Though colorectal cancer is curable if diagnose earlier but in many cases, the symptoms are very late. The symptoms depend on the size, location, kind of the tumor.

For instance, the tumors present in the left side of the abdomen don’t cause any obstruction and there is no change in the stool and bowel movements.

But the tumor on the left side grows into the lumen and causes an obstruction that leads to vomiting, diarrhea, less stool output, bloating, and abdominal pain.

Earlier screening

Colonoscopy now is considered the best screening option for determining colorectal cancer. It’s very easy and helps in the detection of the polyps residing in the colon. A person of age 50 and above must go for the screening and people with a family background should start screening above age 40.

Other common methods of screening are:

  • Sigmoidoscopy
  • Biopsies
  • Ct scanning
  • MRI


There are four total stages of colorectal cancer written as 0 to IV.

Colorectal cancer has a very slow progression. There are chances to detect the polyp at an earlier stage and start treatment.


Cancer has many options as treatment. The most common treatment worldwide are:

  • Chemotherapy
  • Radiotherapy
  • Surgery

The type of treatment is decided after determining the stage of cancer and the condition of the patients.

Almost 75% of colorectal cases are treated with removal of the polyps or the tumors along with lymph nodes. The main surgeries are termed as:

  • Anastomosis
  • Resection of colostomy
  • Abdominoperineal resection

If only a small portion of the colon is removed then the remaining parts can be stitched together. But if there is major surgery and the whole colon is removed then a colostomy is needed which results in a stoma on the abdomen.

Surgery is the best option for patients with stage 0 to II cancer.

The patients at stages III & IV need chemotherapy. Chemotherapy involves drugs that enter the body and destroy the cancerous cells.

Radiotherapy is another option for patients with colorectal cancer. Ultraviolet rays can help in shrinking the tumor and it can be removed after the surgery.