Overview of Colon Cancer

What is Colon Cancer?

Colon Cancer 

Colon cancer is the cancer of intestine and is also called as colorectal cancer depending on if developing in colon or rectum. That is the third most common cancer in men and the second in women globally. Males have a much greater incidence than females. Colorectal cancer is the third leading cause of death. In addition, the world health organization (WHO) predicts that by 2030, there will be 27 million new cases of CRC.

Anatomy of the colon

A widespread illness begins with unusual growth in the layer colon or rectum and progresses to the entire thickness of the epithelial lining before spreading to nearby lymph nodes and tissue and eventually distant metastases. Age is the major risk factor. Although the condition can occur at any age,

Benign to malignant polyp progression

Risk Factors for Colon Cancer

Some factors that increase your risk of bowel cancer include:

• Inherited genetic risk and family history
• Inflammatory bowel disease such as Crohn’s disease
• High red meat consumption, especially processed meats
• Polyps
• Being overweight or obese
• High alcohol consumption
• Smoking tobacco
• Having a previous diagnosis of bowel cancer.

Symptoms of Colon Cancer

In the early stages, people with bowel cancer often may not experience pain. However, the following symptoms may indicate colon cancer:

• Blood in stools
• Change in the bowel habits, such as thin stools, diarrhoea, and constipation
• Unexplained weight loss
• Fatigue
• Abdominal pain

Bowel cancer is diagnosed by symptoms, medical history and other diagnostic procedures.

Screening and Diagnosis 

By using a non-invasive test for blood in the faeces that can be done at home, known as the faecal occult blood test (FOBT), the test is only for low-risk people with no symptoms of bowel cancer. The FOBT is not for people with a family history of bowel cancer. In this case, you may need screening colonoscopies.

• These procedures include:

Colonoscopy- It is a procedure done for inspecting the inside of the entire colon. It is performed using an instrument called colonoscope, a flexible tube with a tiny camera. If the bowel cancer is confirmed, staging is performed to detect the size, location, and stage of the cancer.

Sigmoidoscopy- It is a test performed for the examination of the inside of the large bowel and the rectum.

Barium enema- In this procedure barium containing fluid is administered into the bowel through rectum. X-ray images are then captured to view inside the bowel.

Staging for Colon Cancer

Staging is performed using ultrasonography or a computed tomography of the abdomen, chest X-rays, Magnetic Resonance Imaging (MRI) scans of the bowel, and complete blood count. Faecal occult blood test- Faecal occult blood test (FOBT) is a test to determine small amounts of blood in the faeces. However, this test does not diagnose colon cancer, hence need to be performed during colonoscopy or sigmoidoscopy.

Treatment of Colon Cancer

Treatments depend on the size, location, and stage of the cancer. Severity of the bowel cancer may range from stage 0 (early stage; restricted to particular area) to stage 4 (advanced stage; spread to other parts of the body). Bowel cancer may be treated using chemotherapy, radiation therapy, and/or surgery.

There are two main categories of treatments for colon cancer.

Local treatments

The most common treatment for bowel cancer is surgery. More often a colectomy is performed, to remove the cancer cells. It is the surgical resection of all or part of the large intestine. The surgery is also called large bowel resection. Colectomy is performed under general anaesthesia by open surgery method or by laparoscopic method. The procedure takes about 1 to 4 hours.

Many early colon cancers (stage 0 and some early stage 1 tumours) and most polyps can be removed during a colonoscopy.1 During a polypectomy, the cancerous polyp is cut at the stalk using a wire loop instrument that is passed through the colonoscope, which is a long, flexible tube with a camera and light at its tip.

A laparoscopic procedure requires a much smaller incision than an open colectomy, so recovery is generally faster.

During a colectomy, the diseased section of the colon is removed, along with an adjacent part of the healthy colon and lymph nodes. Then, the two healthy ends of the bowel are reattached. The surgeon's goal will be for the patient to return to the most normal bowel function possible. This means that the surgeon will take out as little of the colon as possible.

As with other surgeries, colectomy procedure is also associated with complications such as infections, bleeding, and damage to nearby organs.

High fibre diets and vitamins, avoiding smoking and alcohol, managing obesity and a healthy life style can lessen risk of bowel cancer.

Systemic Therapy

Bowel cancer can be treated using anti-cancerous medications or radiation depending on the site and severity of cancer. These treatments can be used as alone or in addition to surgery to destroy the remaining cancer cells and to prevent from further spreading.Unlike radiation, these options affect the entire body, instead of zeroing in on a specific area.

Chemotherapy drugs travel throughout the body and kill cells that are dividing (growing or duplicating) rapidly. Though the treatment doesn't distinguish between cancerous cells and healthy, fast-dividing cells (like those in hair or nails), the latter will be replaced upon completion of chemotherapy.

The majority of people with stage 0 or stage 1 colon cancer will not require chemotherapy. For those with later stage colon cancer, chemotherapy may be given prior to surgery to shrink the tumours before physical removal.

Chemotherapy is also sometimes used to shrink tumours throughout the body when systemic metastasis has occurred (in stage 4 cancer).

Chemotherapy may be administered in conjunction with other colon cancer treatments (for example, surgery or radiation) or by itself.

Some of the chemotherapy drugs used to treat colon cancer include:

• 5-FU (fluorouracil)
• Eloxatin (oxaliplatin)
• Xeloda (capecitabine)
• Camptosar (irinotecan, irinotecan hydrochloride)
• Trifluridine and Tipiracil (Lonsurf)

Some of these agents are given concurrently with chemotherapy once every one to three weeks, including:

• Avastin (bevacizumab)
• Erbitux (cetuximab)
• Vectibix (panitumumab)
• Zaltrap, Eylea (aflibercept)
• Others Cyramza (ramucirumab) may be administered alone. Tyrosine kinase inhibitors, such as Stivarga (regorafenib), are administered orally.

All treatments present a risk of side effects. The benefits of your treatment should outweigh the risks. Your healthcare provider will work with you closely and tailor your treatment program to your needs.

Prognosis for Bowel Cancer

Prognosis refers to the expected outcome of a disease. It is not possible for any doctor to predict the exact course of the disease. An individual's prognosis depends on the type and stage of cancer, as well as their age and general health at the time of diagnosis. This information will also help your doctor to advise on the best treatment options.

And here, my friends, we have finished today’s essay, in which I have provided you with everything that can help you to understand what is colon cancer, and what is the risk of colon cancer. In our next essay, we will talk about the effect of some vitamins and minerals on the occurrence and preventing of cancer

If you want to ask about a specific topic, write it to us in the comments

Written by: Husam Hussein