Contents
In this article, we will take a look at:
- What is Bowel Cancer?
- How does Bowel Cancer occur?
- Who is prone to bowel cancer?
- Symptoms of bowel cancer
- Diagnosis of bowel cancer
- Complications of a bowel cancer
- Treatment for bowel cancer
- In the Spotlight
You can click on any of the links above to navigate to the section of your interest.
What is Bowel Cancer?
To understand this better, let us first define what cancer is. Cancer or malignancy is a condition where there is an uncontrolled multiplication of abnormal cells.
There are various types of cancers and when it occurs in the large intestine (colon) or rectum, it is called bowel cancer. Hence, bowel cancer medically is known as colon cancer or rectal cancer (or collectively colorectal) cancer depending on the exact location of the growth.
Most of the bowel cancers are assumed to originate in the wall linings of the colon or rectum. Such growths are known as polyps or adenomas. In some cases, these growths may remain as polyps and not develop into bowel cancer.
Bowel cancers can be categorized on the basis of the type of cell undergoing abnormal multiplication.
The different types of bowel cancers are:
Adenocarcinoma- This is the most common kind. The glandular cells present on the linings of the bowel contain the tumor.
Squamous Cell Cancer- The squamous epithelium forming the bowel lining is where cancer originates.
Carcinoid Tumours-These have a neuroendocrine origin where usually the stem cells that form the lining of the intestines become malignant. Epithelial cells are affected.
Sarcomas- This is a very rare condition where cancer occurs in the non-epithelial cells.
Lymphoma- The lymph nodes are where the malignancy originates from.
How Does Bowel Cancer Occur?
Usually, bowel cancers begin with small growths that form on the linings of the walls of the colon or rectum, known as polyps. This occurs in the inner lining of the bowel. Many of these polyps are benign and therefore harmless. Some of them, however, become malignant with time.
Malignancy usually occurs when cells undergo mutations, which could be due to genetic causes. The cells no longer follow the usual cell cycle and thereby have an extended lifespan. They also multiply in alarming quantities, thereby forming a mass or tumor.
Bowel Cancer occurs in stages and the TNM staging system is recognized as a standard in staging colorectal cancer. Staging helps the doctors devise the best management plan for cancer as each stage needs different treatments and care.
Stage 0 - It is also known as carcinoma in situ. This is the earliest stage of bowel cancer where the cancer cells have not metastasized (they are contained within the bowel)
Stage 1 - Cancer has spread through the lining and may have penetrated into the muscular layer of the bowel. The lymph nodes have not been breached yet. The cancer is still localised.
Stage 2 - It has two subsections. Stage 2A- Cancer has reached the outer lining of the bowel and no lymph nodes have been affected. Stage 2B- Cancer has reached further beyond the outer lining of the wall and into the adjacent tissues and organs. Stage 3 - It has three subsections: Stage 3A- One to three lymph nodes may be affected, but the adjacent organs and tissues are not affected as the cancer are contained within the inner lining of the bowel Stage 3B- Outer lining, surrounding tissues and one to three lymph nodes are affected. Stage 3C- Four or more lymph nodes have been affected.
Stage 4 - It is the final stage. Other organs are involved. Metastasis through blood and lymph has occurred.
Who is Prone to Bowel Cancer?
Bowel cancer has various risk factors that may predispose a person to it. Some such risk factors are
Age: People over 50 years of age are more prone to colorectal cancer.
Lifestyle: Obesity, alcohol consumption, smoking, red meats are some risk factors.
Presence of Polyps- The larger the number of polyps presents in the bowel, the higher the chance of some of them turning malignant.
Family History: A strong family history is a risk factor especially with two close relatives suffering or having suffered from bowel cancer.
Diseases of the Bowel: People with chronic diseases of the bowel such as Crohn’s disease, Inflammatory Bowel Disease or Ulcerative Colitis lasting for over eight years have a high chance of developing bowel cancer. Other Diseases: Patients who have previously suffered from bowel cancer are more prone to it along with other types of cancers such as endometrial cancer.
Genetic Predisposition
What are the symptoms of bowel cancer? How is bowel cancer diagnosed?
The common symptoms often noted are:
- Pain in the abdominal region.
- Blood in stools
- Constipation or diarrhea
- Narrowing of the stools passed
- Excessive flatulence- too much gas passed often
- Anaemia characterized by weakness, fatigue
- Weight loss- rapid and abnormal
Diagnosis
To diagnose bowel cancer, the following tests are done. Routine physical examination is conducted to look for any abnormal weight loss. Routine blood tests can show a presence of low blood count pointing to anaemia. Faecal Occult Blood Test looks for the presence of minute amounts of blood in the stools and is a screening test.
Colonoscopy confirms the presence of cancer. A colonoscope- which is a bendable tube attached with a camera is inserted through the rectum after cleaning out the patients bowels. As an alternative for physical colonoscopy, virtual colonoscopy can be done using an imaging method such as a CT scan or MRI but it is not as accurate. Sigmoidoscopy allows the doctor to check a specific part of your colon.
What are the complications of bowel cancer?
Recurrence is the main and most significant complication of bowel cancer. The other complications usually seen are-
- Intestinal obstruction causing a blockage so the faecal waste is unable to travel through the intestine.
- Metastasis can occur in later stages and this affects the functioning of the other organs, as cancer spreads to the lungs and the liver usually.
What is the treatment for bowel cancer?
Treatment of colon cancer is stage-wise. Treatment options include:
Surgery, where either polyps can be removed assisted by colonoscopy or parts of the colon can be removed so that the cancer cells are completely removed, depending on the infiltration. Laparoscopic surgery is also done in some cases.
Alternative pathways for the faecal matter to be excreted may be created by surgeons in case major parts of the bowel cannot be saved.
Chemotherapy involves using strong and powerful medicine to destroy and kill the cells that multiply abnormally. Immunotherapy works by modulating the immune system of the body in such a way that the malignancy is controlled. Radiation therapy is used to cause immediate cell death of the malignant cells.
Treatment using targeted drugs is favourable to many of the patients and uses targeted medication that might eventually control and put an end to the malignancy. Pain and Palliative Care is the care provided during the end stage of the disease where the patient’s pain is managed using various medications.
In the Spotlight
- Recent studies have shown that lifestyle choices significantly affect the chances of being affected by colon cancer.
- A study found that 45% of the cases could be attributed to a nonhealthy lifestyle.
- The factors considered in the study were smoking, alcohol habits, improper diet, physical inactivity, and excess body fat.
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