Rectal Cancer is defined as the growth of abnormal cancerous cells in the lower part of the colon that connects the anus to the large intestine. The rectum is the last few inches of the large intestine that starts from the end of the colon and ends when it reaches the short, narrow passage leading to the anus. The rectum usually stores bowel for evacuation. Also Read: Pancreatic Cancer: Causes, Symptoms And Treatment

rectal cancer causes

The rectum has 3 layers which are:


Composed of glands, this is the innermost cellular lining of the intestine and mainly secretes mucous that helps in the passage of stool.

Muscularis propria:

This is the middle layer of the rectal wall and is mainly composed of muscles that not only helps in maintaining the shape of the rectum but also helps in expelling out the faeces from the body.


It is the outermost layer and consists of fatty tissues.

Rectum Cancer is more common in men than in women. Rectal cancer is generally witnessed in the form of adenocarcinoma which is cancerous tumours arise in the mucosal layer. Since the rectum is surrounded by lymph nodes, cancerous cells can also spread from the rectum to the lymph nodes on their way to other parts of the body. Also Read: Lymphoma: Causes, Symptoms And Treatment


Although the exact cause is yet unknown, the most common cause of cancer is due to the presence of faulty DNA that causes cells to grow out of control. These abnormal faulty cells do not die but accumulate and form tumours. Rectal cancer can occur due to inherited genetic mutation and syndromes called Lynch syndrome and Familial adenomatous polyposis syndrome.

Other factors include:

  • Older age
  • Polyps in the colon or rectum
  • Inflammatory bowel disease, Crohn’s disease or Ulcerative colitis
  • Breast, ovary or uterine Cancer
  • Obesity
  • Type 2 diabetes
  • A diet lacking vegetables and fruits
  • Lack of exercise
  • Addiction to smoking and drinking


The common signs and symptoms of rectal cancer include:

  • Diarrhoea
  • Constipation
  • Frequent bowel movements
  • Mucous in stool
  • Extreme narrow bowels
  • Blood mixed stool
  • Prolonged rectal bleeding
  • Abdominal pain
  • Painful bowel movements
  • General debility
  • Iron deficient anaemia
  • Sudden weight loss
  • Feeling that the bowel isn’t empty completely


It is strictly advocated to consult a doctor at the earliest if you notice any of the above-mentioned symptoms. The doctor usually does a thorough physical examination and acknowledges the patient’s past medical history. He also performs a few medical tests including:

  • Colonoscopy
  • Faecal occult blood test
  • Endoscopy
  • Digital rectal examination
  • Flexible sigmoidoscopy
  • Rigid sigmoidoscopy
  • Ultrasounds

Stages Of Rectal Cancer:

Stage 0:

Cancer cells usually develop on the surface of the rectal lining (i.e. mucosal layer), sometimes within a polyp.

Stage I:  

Tumorous cells encompassing below the rectal mucosa, and in some cases penetrating the rectal wall.

Stage II:

In this stage, the cancer cells spread into or through the rectal wall, reaching and growing on or sticking to tissues next to the rectum.

Stage III:

Spread of cancer to the lymph nodes next to the rectum, as well as structures and tissues outside the rectal wall.

Stage IV:

The cancerous cells have spread to distant organs or lymph nodes from the rectum.

Once the rectal cancer is diagnosed, it is necessary to stage the cancer cells to avail the most appropriate treatment option. Staging is usually done through the following techniques:

  • Chemistry Panel
  • Complete Blood Count
  • Carcinoembryonic antigen
  • CT-scan of chest
  • MRI of the pelvis


Rectal cancer often requires more than one treatment and is done based on the stage of cancer. The treatment options involve:

  • Surgery: This includes Abdominoperineal resection with end colostomy, Coloanal anastomosis, low anterior resection, local excision and more extensive surgery
  • Chemotherapy
  • Radiation therapy
  • Targeted therapy
  • Immunotherapy
  • Combination therapy