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Colon Cancer: Causes, Symptoms, Signs & Treatment

Colon is the longest part of the large intestine and lowermost part of the digestive system. Colon cancer or colorectal is the second major cause of cancer death. The disease is slightly more common in men than women and the risk of colon cancer increases with age. Water and salt from the solid waste after digestion from small intestine get extracted inside the colon, before it moves into the rectum for elimination from the body.

What Is Colon Cancer?

The uncontrolled growth of cells lining the large intestine is known as colon cancer.  In most cases the colon cancer begins as small non cancerous or benign tumors known as adenomatous polyps. Over the course of time some of these polyps may grow into malignant tumors. It is better to have regular screening tests to identify polyps before they turn into colon cancer. The polyps can be removed by colonoscopy.  The cancerous cells may travel through the blood and lymph and may spread to other healthy parts. Colon cancer and rectal cancer are not the same, but they often occur together and are known as colorectal cancer.

Causes Of Colon Cancer

No specific causes are identified for colon cancer. When the cells uncontrollably grow and do not die, it results in cancer. There are certain factors which increase the risk of colon cancer. They include:

  • Genetics –20 % of colon cancers are caused by inherited mutations in the genes
  • Polyps- Adenomas and inflammatory polyps may become cancerous
  • Habits And Diet- Sedentary lifestyle, smoking, alcohol consumption, low fiber diets, fat and calorie rich diets , red meat etc increases the chance of colon cancer
  • Certain Medical Factors- Health conditions such as diabetes, ulcerative colitis, acromegaly, Crohn’s disease and radiation treatment for other cancers increases the risk of colon cancer.

Symptoms Of Colon Cancer

In the earliest stages of colon cancer the person may not experience any symptom. When the cancer reaches the advanced stage the following symptoms are seen:

  • Diarrhea or constipation
  • Changes in stool consistency
  • Stomach pain
  • Weight loss
  • Blood in stool or rectal bleeding
  • Continual urges to defecate
  • Anemia
  • Irritable bowel syndrome

When cancer metastasizes or spreads to other parts, additional symptoms will be present in the newly affected area. The liver is the most common place for metastasis.

Colon Cancer Symptoms In Men

There are not much variation in the symptoms seen in men and women affected by colorectal cancer, the common symptoms in men includes:

• Change in bowel habits, such as constipation or diarrhea
• Narrowing of stools that lasts more than a few days
• Rectal bleeding, blood in the stool or dark stools
• Unintended weight loss
•  Weakness and fatigue

Colon Cancer Symptoms In Women

Some of the common symptoms of colon cancer in women are:

• Changes in bowel movement including constipation or diarrhea
• Feeling of not able to empty the bowel completely
• Rectal cramping or rectal  bleeding
• Blood in stool or thin stools
• Abdominal discomfort and bloating
• Unexplained fatigue, loss of appetite and weight loss
• Pelvic pain

Signs Of Colon Cancer

There are several non-specific signs of colon cancer. The signs may vary according to the position of the tumor in large intestine. A cancer on the right side of the colon cause iron deficiency anemia as loss of blood occurs over a long period of time. The signs of cancer on the right side of colon are:

• Fatigue and weakness
• Shortness of breath

The tumor in the left part of the colon is likely to cause partial or complete bowel obstruction. The most common signs include:

• Diarrhea or constipation
• Red or dark blood in stool
• Abdominal pain
• Stomach cramps and bloating
• Weight loss

Metastatic Colon Cancer

Sometimes the cancer cells from one area of the body can spread to other parts of the body this is known as secondary spread or metastasis.  The cells of the colon cancer can travel through the lymphatic system or bold stream and can spread to the liver, bones or any other organ. The exact cause of metastatic colon cancer is not known.

Colon Cancer Stages

To diagnose colon cancer the physician may conduct colonoscopy or barium enema X-ray. The polyps detected by colonoscopy, they are removed and sent for biopsy to detect cancer cells. After diagnosis the stage of the cancer is identified. The colon cancer stages are identified using the method called the TNM system. T indicates the size and extent of the primary tumor or degree of invasion of cancer cells into the intestinal wall, N indicates the degree to which the cancer has spread to the lymph nodes and M indicates whether the cancer has metastasized to other organs of the body.

Colon Cancer Surgery

Your doctor may suggest colon cancer surgery to slow the spread of cancer, to remove bowel block or to remove secondary invasion. The surgery to remove part or entire colon is known as colectomy. During this surgery the surgeon will remove part of colon having cancer cells and the areas adjoining it. The nearby lymph nodes are also removed as a precaution to avoid secondary cancer. Doctors use endoscopy to remove small localized cancers. Larger polyps are often removed by laparoscopic surgery. In advanced or untreatable cases palliative surgery is employed to relieve the symptoms such as pain, bleeding etc.

Colon Cancer Treatment

The treatment of colon cancer depends on the type of cancer, the size of the tumor, the stage of the cancer, the age of the person, the health status of the patient etc.  There is no single treatment which is effective for colon cancer. The commonly used treatments are

  • Chemotherapy – This uses chemicals which destroy the cancer cells. It is highly effective for metastasized cancer.  There are side effects such as hair loss, nausea, fatigue, and vomiting for this treatment.
  • Radiation Therapy – This use high energy gamma rays to destroy cancer cells. These are effective in shrinking tumors. Side effects of radiation therapy include mild skin changes like sunburn or suntan, nausea, vomiting, diarrhea, and fatigue. Patients tend to lose their appetites experience weight loss, but most of these side effects subside a few weeks after completing treatment.
  • Surgery – If the colon cancer is causing symptoms it is better to operate, to remove the affected colon part. Your doctor will be able to suggest the best treatment option for you after considering various factors.

Regular screening is the best method to detect and prevent colon cancer. Keeping healthy weight, consumption of fiber containing fruits and vegetables, reducing fat and red meat intake and exercising also helps to prevent colon cancer.