The colon, a tube five feet long, also known as the large intestine, plays a crucial role in absorbing water and nutrients from food. The rectum, located at six inches of the tract, functions as a storage area for stool before it is expelled from the body through the anus. The colon is segmented into four parts: the ascending colon, the descending colon and the sigmoid colon.

Most cases of cancer originate in the sigmoid colon. In the region just above the rectum. Typically originating from the layer of tissue, these cancers can progress through layers that compose both the colon and rectum. The depth of penetration into these layers dictates the stage of cancer progression. Colorectal cancers often develop slowly over years, usually starting with benign growths called polyps and removing these polyps. Before they turn, it proves to be an effective strategy in preventing colorectal cancer.

Are all cases of colon and rectal cancer fatal? Not necessarily. Timely detection and proper treatment significantly enhance the prognosis for individuals with cancer. With identification, more than 60 percent of colorectal cancer cases can be cured entirely. Therefore, it is crucial to address any symptoms and consider regular screening if there is a family history of cancer.

Screening should begin around age 50, as is expected in the United States.

Who is more likely to develop colon and rectal cancer?

Age plays a role for individuals over 50.
A diet that is low in fibre and high in fat is linked to an increased risk of colon cancer. Consuming meat and processed meat may heighten this risk.
Sedentary lifestyle can increase the risk of colon cancer.
Individuals with diabetes or insulin resistance may face a chance of developing colon cancer.
Excessive weight increases the likelihood of both developing and succumbing to colon cancer compared to those with lesser weight.
Smoking cigarettes might elevate the risk of colon cancer.
Heavy alcohol consumption can also raise the chances of developing colon cancer.
Past abdominal radiation therapy for treating forms of cancer could potentially increase the risk of developing colon cancer.
If you have previously experienced colon cancer or adenomatous polyps, your chances of developing colon cancer in the future are higher.

Signs and Symptoms of colon and rectal cancer

Colorectal cancer sometimes arises without any symptoms. When symptoms do occur, however, they may include the following:

rectal bleeding or blood in the stool
a change in bowel habits (such as diarrhoea, constipation) for no apparent reasons that lasts for more than a few days
abdominal pain
a continuous feeling that you need to have a bowel movement, which does not resolve after passing stool
weakness
tiredness (due to anaemia, which may also cause breathlessness)
unexplained weight loss
can present with blockage (obstruction) in the bowel. Symptoms of this are
- constipation
- vomiting
- abdominal distension
- a bloated feeling
- pain abdomen

*Any rectal bleeding or blood in the stool should be brought to your doctor's attention. Although these symptoms can be caused by conditions other than cancer of the colon and rectum, it's essential always to have them checked by your doctor.

Diagnosis of Colon and Rectal Cancers

Colorectal cancer diagnosis may involve one or more of several procedures:

Proctoscopy – the short tube that goes just into the rectum to examine it
Sigmoidoscopy – longer tube that can be passed further up into the distal part of the large bowel

A colonoscopy inspects the rectum and entire colon using a thin tube with a light and camera on the end. It is inserted into the rectum while the patient lies on their side. Patients often receive a mild sedative during this procedure to ensure their comfort. Any polyps or other growths found during these examinations are usually removed at that time and sent to a laboratory for analysis.

Faecal Occult Blood Test - Also known as a stool blood test, this laboratory test looks for blood in the stool.
Virtual Colonoscopy - Virtual colonoscopy is a new technique that uses CT scans to create a 3-D image that can be used to evaluate the bowel. It is also important to note that while this technique is promising, it does not allow for a biopsy or polyp removal when an abnormality is found.

Tests Required for the Diagnosis of Colon and Rectal Cancer

If tests show that you have colorectal cancer, additional examinations may be performed to determine its extent - a process called staging.

Computed tomography (CT) and magnetic resonance imaging (MRI) scans may be used to see if the cancer has spread to other organs, such as the liver and lungs.
Chest x-ray, which may be performed to see if the cancer has spread to the lungs
Blood test for CEA, a protein that acts as a marker for colorectal cancer

Depending on your specific clinical situation, these additional tests may be ordered:

Positron-emission tomography (PET) scanning may be conducted to determine whether cancer has spread to other parts of the body.
An endorectal ultrasound probe uses sound waves to produce an image of the tumour, and it may be placed in the rectum to see how far a cancer has invaded the rectal wall. This procedure is used for staging rectal cancer only.

What are the stages of colon and rectal cancer?

Stage 1 – cancer has not spread beyond the original tumour.
Stage 2 – Tumors may have grown through the bowel wall and into nearby tissues but have not spread to new body parts.
Stage 3 – Tumor cells can be found in nearby lymph nodes.
Stage 4 – The tumour has spread to other parts of the body.

Treatment Options for Colon & Rectal Cancer

Surgical removal of the cancer along with adjacent healthy colon or rectum is the gold standard treatment for the cure of this cancer. However, the use of chemotherapy and radiotherapy before and after the surgery increases the chances of cure, decreases the recurrence of cancer and increases the survival of the patient.

Surgery. Cancerous tumours in the colon can be safely removed with surgery. The type of surgery depends on the tumour's size and location. Partial colectomy is a surgical procedure in which a part of the colon or the rectum containing the tumour is taken out along with a surrounding healthy tissue, which is reconnected later. Sometimes, a colostomy is performed in which the healthy end of the large intestine is brought out on the anterior abdominal wall as a stoma.

Right hemicolectomy for right sided colon cancer

Right hemicolectomy for right sided colon cancer

Left hemicolectomy for left-sided colon cancer

Left hemicolectomy for left-sided colon cancer

Sigmoid colectomy for sigmoid colon cancer

Sigmoid colectomy for sigmoid colon cancer

Anterior resection for upper and middle rectal cancer

Anterior resection for upper and middle rectal cancer

Abdominoperineal resection for lower rectal and anal canal cancers

Abdominoperineal resection for lower rectal and anal canal cancers

Chemotherapy

It is usually initiated after the colon tumour is surgically removed to prevent recurring tumours. A combination of anticancer drugs may be administered orally or directly into the bloodstream. It is used along with radiation therapy for rectal cancers.

Radiotherapy

High-energy rays kill cancer cells and stop their growth while harming normal cells as little as possible. It is sometimes used before surgery to shrink the tumour size so that the tumour can be completely removed during surgery.