Colorectal cancer: Symptoms, treatment, risk factors, and causes

Colorectal cancer, also known as bowel cancer, colon cancer, or rectal cancer, is any cancer that affects the colon and the rectum.

The American Cancer Society estimate that about 1 in 21 men and 1 in 23 women in the United States will develop colorectal cancer during their lifetime.

It is the second leading cause of cancer death in women, and the third for men. However, due to advances in screening techniques and improvements in treatments, the death rate from colorectal cancer has been falling.

Colorectal cancer may be benign, or non-cancerous, or malignant. A malignant cancer can spread to other parts of the body and damage them.


Anatomy of the large intestine
The large intestine is also called the colon or large bowel.

Symptoms of colorectal cancer include:

changes in bowel habits

diarrhea or constipation

a feeling that the bowel does not empty properly after a bowel movement

blood in feces that makes stools look black

bright red blood coming from the rectum

pain and bloating in the abdomen

a feeling of fullness in the abdomen, even after not eating for a while.

fatigue or tiredness

unexplained weight loss

a lump in the abdomen or the back passage felt by your doctor

unexplained iron deficiency in men, or in women after menopause

Most of these symptoms may also indicate other possible conditions. It is important to see a doctor if symptoms persist for 4 weeks or more.


Treatment will depend on several factors, including the size, location, and stage of the cancer, whether or not it is recurrent, and the current overall state of health of the patient.

Treatment options include chemotherapy, radiotherapy, and surgery.

Surgery for colorectal cancer

This is the most common treatment. The affected malignant tumors and any nearby lymph nodes will be removed, to reduce the risk of the cancer spreading.

The bowel is usually sewn back together, but sometimes the rectum is removed completely and a colostomy bag is attached for drainage. The colostomy bag collects stools. This is usually a temporary measure, but it may be permanent if it is not possible to join up the ends of the bowel.

If the cancer is diagnosed early enough, surgery may successfully remove it. If surgery does not stop the cancer, it will ease the symptoms.


Chemotherapy involves using a medicine or chemical to destroy the cancerous cells. It is commonly used for colon cancer treatment. Before surgery, it may help shrink the tumor.

Targeted therapy is a kind of chemotherapy that specifically targets the proteins that encourage the development of some cancers. They may have fewer side effects than other types of chemotherapy. Drugs that may be used for colorectal cancer include bevacizumab (Avastin) and ramucirumab (Cyramza).

A study has found that patients with advanced colon cancer who receive chemotherapy and who have a family history of colorectal cancer have a significantly lower likelihood of cancer recurrence and death.

Radiation therapy

Radiation therapy uses high energy radiation beams to destroy the cancer cells and to prevent them from multiplying. This is more commonly used for rectal cancer treatment. It may be used before surgery in an attempt to shrink the tumor.

Both radiation therapy and chemotherapy may be given after surgery to help lower the chances of recurrence.


Ablation can destroy a tumor without removing it. It can be carried out using radiofrequency, ethanol, or cryosurgery. These are delivered using a probe or needle that is guided by ultrasound or CT scanning technology.


Malignant tumors can spread to other parts of the body if left untreated. The chances of a complete cure depend enormously on how early the cancer is diagnosed and treated.

A patient’s recovery depends on the following factors:

the stage when diagnosis was made

whether the cancer created a hole or blockage in the colon

the patient’s general state of health

In some cases, the cancer may return.

Having polyps increases the risk of colorectal cancer.

older age

a diet that is high in animal protein, saturated fats, and calories

a diet that is low in fiber

high alcohol consumption

having had breast, ovary, or uterine cancer

a family history of colorectal cancer

having ulcerative colitis, Crohn’s disease, or irritable bowel disease (IBD)

overweight and obesity


a lack of physical activity

the presence of polyps in the colon or rectum, as these may eventually become cancerous.

Most colon cancers develop within polyps (adenoma). These are often found inside the bowel wall.

Eating red or processed meats may increase the risk

People who have a tumor suppressor gene known as Sprouty2 may have a higher risk of some colorectal cancers.

According to WHO (World Health Organization) colorectal cancer is the second most common tumor among both men and women, after lung tumors.

Around 2 percent of people aged over 50 years will eventually develop colorectal cancer in Western Europe.

Colorectal cancer tends to affect men and women equally. However, men tend to develop it at a younger age.

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