Colon Cancer


1. What is colon? Where is it located ?

The colon is a part of the body's digestive system. The digestive system is made up of the esophagus, stomach, small and large intestine. The main part of the large intestine is called the colon, which is about 150cm long. This is split into five sections: the caecum, ascending, transverse, descending and sigmoid colon. Some water and salts are absorbed into the body from the colon. The colon leads into the rectum (back passage). Major organs lie around the colon including the duodenum, liver, kidney, spleen, and pancreas.

2. Why have I developed colon cancer?

Development of colon cancer cannot be attributed to any single factor. There are certain risk factors which increase the chance of developing colon caner. Risk factors include
  • Age- colon cancer is more common in older people (50 and above)
  • A family history of cancer of the colon or rectum
  • A personal history of the colon, rectum, ovary, endometrium or breast cancer
  • A history of ulcerative colitis or Crohn's disease (conditions of the colon) for more than 8-10 years
  • Obesity
  • Lifestyle factors- little exercises, drinking lot of alcohol
  • Certain hereditary conditions such as familial adenomatous polyposis, hereditary nonpolyposis colon cancer (HNPCC, Lynch syndrome)
However, patients may develop these cancers even without any of these risk factors being present.

3. What are the symptoms of colon cancer?

The presentation of colon cancer depends on the site of the tumour. A doctor should be consulted if any of the following occur:
  • A change in bowel habits
  • Blood (either bright red or very dark) in the stool
  • Diarrhea, constipation or feeling that the bowel does not empty completely
  • Frequent gas pains, bloating, fullness or camps
  • Weight loss for no reason
  • Feeling very tired
  • Vomiting
In western countries, owing to the higher incidence of colorectal cancer, screening strategies are employed. By this, all patients above the age of 40 years are advised to have a faecal occult blood test every 6 months. If positive, the patent is sent for a colonoscopy. In India, while a formal screening programmme does not exist, it is advisable for adults above the age of 40 years, especially those with a family history of bowel cancer, to get themselves tested for faecal occult blood by visiting their family physician.

Unexplained anemia is another form of presentation. If the cancer spreads to other parts of the body, various other symptoms can develop depending on the site of spread. Colon cancer can also present with complications such as intestinal obstruction, intestinal perforation and bleeding. All the above symptoms can be due to other conditions, so tests are needed to confirm colon cancer.

4. What investigations will I be subjected to?

The best investigations to diagnose colon cancer is colonoscopy with a biopsy of the tumour. A computer tomography (CT) scan of the abdomen and pelvis will help to support the diagnosis of the cancer as well to determine whether the cancer is at an early stage or whether it has spread to the lymphnodes, liver or other organs and if the colon cancer has infiltrated the surrounding organs. Serum CEA (a blood test) is a marker used in colon caner. It is especially useful to follow response to treatment and surveillance. After curative surgery, its level becomes normal. Thus it is routinely performed at follow up to help detect recurrence of the caner. Liver function tests, chest X-ray and or CT scan, etc. are other investigations to decide the stage of the disease. If an operation is being planned, some more tests may be necessary to decide fitness of the patient for general anaesthesia.

5. Are there different types of colon cancer?

Yes, there are different types of colon cancer depending on the type of cell/tissue from which the cancer is arising.
Adenocarcinoma is the most common type of colon cancer. Gastrointestinal stromal tumours (GIST), lymphoma, leiomyoma are some of the less common type of colon cancers. The treatment depends on the type of cancer.

6. At what stage is the cancer?

Accurate staging of the cancer is based on histopathology and will be possible only after surgery. Colon cancer can be broadly classified into

Stage 1: Early cancer: cancer only within the colon with no spread of disease outside of it.
Stage 2: Locally advanced- when the cancer appears large and/or invading other surrounding organs, with enlarged lymphnodes
Stage 4: Metastatic- When the cancer has spread far from the colon, for e.g to the liver, lungs, etc. These patients also usually have some fluid building up in the abdomen.

7. Now that I have been diagnosed to have colon cancer, how will I be treated?

Different types of treatment are available for patients with colon cancer. Three types of standard treatment are used.
  • Surgery
  • Chemotherapy
  • Targeted Therapy
Surgery is the most common treatment for all stages of colon cancer. Some patients may be given chemotherapy after surgery to kill any cancer cells that are left. Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells either by killing the cells of stopping them from dividing. Targeted therapy uses drugs or substances to identify and attack specific cancer cells without harming normal cells.

8. Which kind of surgery is done for colon cancer?

The type of surgery depends on the location of the cancer and extent. There are curative and palliative colectomies. Curative surgeries are done with an aim to remove the entire cancer with a margin of normal tissues around and all the lymphnodes involved(lymphadenectomy). These include:
Right hemicolectomy refers to the resection of the caecum and ascending colon.
Left hemicolectomy refers to the resection of the descending colon, Extended hemicolectomy is when a part of the transverse colon is also resected.
Sigmoid colectomy refers to the resection of the sigmoid colon.
Total colectomy refers to the resection of the sigmoid colon.
Total colectomy refers to the resection of the entire colon.
Subtotal colectomy refers to the resection of the part of the colon or a resection of the entire colon without complete resection of the rectum.
Palliative surgery is done for symptoms control and not with intent for cure. This is because these surgeries are done on patients with advanced disease who have developed complications of the cancer (mentioned above). In an obstructing advanced cancer, only a bypass of the block (colostomy) may be possible. Sometimes, even if a patient is taken up for emergency surgery due to a complications of the cancer, no resection may be possible if the disease is very advanced and the abdomen will just have to be closed without any further surgical intervention.
In some patients with an obstruction who are not fit for surgery, endoscopic stenting of the tumour may be attempted.

9. Are there any alternatives besides surgery?

To date, surgery is the only proven curative option for colon cancer.

10. How do I prepare myself for surgery?

The preparation is generally similar to any major surgery. If you are a smoker it is absolutely essential to stop smoking. Breathing exercises using the incentive spirometry and football bladder should be started. Follow the anesthetist's advice regarding continuation of medications if you are on them. A high protein diet is preferred to improve nutrition.

11. How major is the surgery? What are the possible complications?

Colectomies with lymphadenectomy and other colon surgeries are deemed as major surgeries with a risk of complications and a very small risk of death (<2%). This means that if 100 people are operated, less than 2 of them have a chance of death.
The complications of colectomies (removal of the colon and lymphnodes and joining back (anastomosis) the healthy bowel/intestine) include:
  • Leak of anastomosis
  • Bleeding from the anastomosis
  • Bladder and ureteric injuries
  • Injury to the duodenum
  • Wound infections

12. For how long do I stay in the hospital?

In an uncomplicated case, hospital stay after surgery is 7-10 days. This may be longer when there are complications.

13. Will I need any further treatment after surgery?
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The decision about adjuvant treatment is based on the final histopathology report which will be available approximately 7-10 days following surgery. If any of the lymphnodes are positive and your general condition is good enough then you may be referred to the medical (GI) oncologist for consideration for chemotherapy.

14. What will be my survival after surgery? Are there any chances of the cancer coming back?

The survival depends on the stage of the disease. The average 5 years survival for all stages after curative surgery for colorectal cancer is between 40-75% depending on the stage of the cancer. As of date there is no foolproof way of predicting which patients will have recurrence and which patient will not.

15. Are there any special precautions I need to take to prevent cancer from coming back?

No there are no such proven precautions.

16. How frequently should I follow up after surgery?

After completion of treatment you will be advised to follow up once in 3-4 months in the first 2 years. Then the frequency will be reduced to once in 6 months for the next 2-3 years. Subsequent follow up will be once a year. During each follow-up you will be asked to do certain blood tests, especially CEA. You may also be advised to get an ultrasound of the abdomen and colonoscopy done. Colonoscopy can show recurrence of polyps or cancer in the colon. In addition to checking for cancer recurrence, patients who have had colon cancer may have an increased risk of cancer of the prostate, breast and ovary. Therefore, follow up examinations should include these areas.