Colorectal cancer is a confusing term that merges two different diseases (colon and rectal cancer), causing confusion among the general population.

Dr. Purnendu Bhowmik, a colon cancer doctor in Kolkata, explains the differences and similarities between colon and rectal cancer.

Two Parts of the Same Organ

The rectum and colon are part of the large intestine. Therefore, in the case of both colon and rectal cancer, the large intestine gets affected. However, the two diseases occur in different places.

Colon cancer occurs anywhere in the colon. The colon is nearly 5 feet long and its primary function is absorbing water from the stool.

Rectal cancer originates in the rectum. The rectum is the colon’s last 12 centimeters (nearly 5 inches). This is where the body stores stools until a person have a bowel movement.

The type and complication of the surgical treatment to treat these two conditions are determined by their location, says Dr. Purnendu Bhowmik, who performs laparoscopic colorectal surgery in Kolkata.

For instance, most of the colon is located in the large space between the bottom of the ribcage and the pelvis, making surgery comparatively easier to conduct.

On the other hand, the rectum is located amidst a crowded neighborhood containing the bladder, uterus and vagina for women or the prostate for men, making surgery difficult.

Shared Symptoms and Diagnosis

Colon and rectal cancer have similar symptoms. These include:

  • Constipation or diarrhoea
  • Stomach or gas pains
  • Black, dark, or red coloured stools
  • Feeling weak or tired

The process of diagnosis is also similar for both types of colorectal cancer. Colonoscopy is the standard procedure. The method involves using a long, thin, flexible tube to see the inside of a patient’s rectum and colon.

Suppose the doctor notices areas that could harbour cancer. In that case, they will remove small tumor samples to examine if the cells are cancerous. Many people develop polyps in the colon, which aren’t cancerous but may need to be removed before they become a problem.


Surgery is the first treatment for colon cancer and involves the removal of a section of the colon. The surgery is called a partial colectomy.

The separated sections of the colon are often reconnected to allow patients to have a regular bowel movement, says Dr. Purnendu Bhowmik, a colon cancer doctor in Kolkata. However, in some cases, reconnection is not possible and the patient would need to undergo a colostomy.

In the case of a colostomy, one end of the colon gets rerouted through an incision in the abdominal wall to develop a stoma. A stoma is an opening on the abdomen where a pouch for collecting faeces is attached.

If a patient’s colon cancer spreads to the lymph nodes or affects a thick section of the colon, a doctor may recommend chemotherapy to destroy the cancer cells.

In the case of rectal cancer, surgery is the primary treatment if doctors think that they can remove the tumour altogether. Additionally, doctors may also recommend chemotherapy and radiation therapy. The therapies help kill any remaining cancer cells or shrink a tumour before surgery.

Doctors try to remove any tissue affected by cancer during rectal cancer surgery without damaging the anal sphincter muscle. The anal sphincter muscle is located at the end of the rectum. The muscle controls the release of stools through the anus. In cases where a rectal tumour occurs too close to the sphincter muscle, the patient will need to undergo a colostomy.If you experience the symptoms of colorectal cancer, consult Dr. Purnendu Bhowmik as early as possible. Early diagnosis of the disease will lead to a better outcome of colon cancer treatment in Kolkata.