Colon cancer, also called as colorectal cancer, is a malignant tumor that arises from the glands present in the inner membrane lining the colon. It is exceedingly common in the US where it is the third leading cancer in men and the fourth leading cancer in women. It usually arises from pre-existing polyps or in patients where the lining of the large intestine has been destroyed by long standing ulcerative colitis.
Most of the patients suffering from colon cancer do not have any symptoms until the tumor has grown to a big size. Therefore, it is important for patients with a high risk of developing colon cancer to undergo regular screening. The symptoms, when present, are numerous and non-specific in nature. Some of the common symptoms which may point in the direction of colon cancer include:
- Change in bowel habits
- Change in bowel consistency
- Feeling of incomplete emptying after a bowel movement
- Diarrhea or constipation
- Abdominal cramps
- Dark stools
- Unexplained weight loss
- Rectal bleeding
- Unexplained iron deficiency anemia
However, it is important to remember that these symptoms can also be seen in Crohn's disease and ulcerative colitis (inflammatory bowel disease). So, if a person notices these symptoms, he should be thoroughly examined in order to rule out colon cancer.
As the lumen of the colon on the right side is larger, the tumor may grow to a large size before becoming noticeable. They may cause slow loss of blood through the stools (dark colored stools), leading to symptoms of iron deficiency anemia. These may include shortness of breath, fatigue and lethargy.
The lumen of the colon on the left side is narrower. Therefore, any growth in the left colon may obstruct the movement of the bowels. This may lead to symptoms like constipation or diarrhea, flatulence, abdominal cramps, and change in bowel habits. Bleeding from tumors present on the left side of colon and rectum may lead to loss of fresh blood in the stools.
As the symptoms of colon cancer are non-specific, patients at high risk should undergo regular screening. The high risk factors for developing colon cancer include:
- Patients above the age of 60.
- History of polyps in the colon or rectum
- Presence of ulcerative colitis or Crohn's disease
- African American descent
- Family history of colon cancer
- Survivor of breast cancer
- Persons with a diet containing lot of fats and low on fiber, like red or processed meats
- Familial adenomatous polyposis (FAP)
- Lynch syndrome, better known as hereditary non-polyposis colorectal cancer
- Excessive drinking of alcohol
Diagnosis: Diagnosis of colon cancer is made with the help of barium enema X-rays and colonoscopy. The patient is given an enema containing barium liquid and is subjected to serial x-rays. The barium lines the colon and any tumor or abnormal growth is visualized on the x-rays in the form of dark shadows. During colonoscopy, the colon and rectum can be directly visualized by the surgeon and in case any suspicious growth is seen, biopsy can also be taken simultaneously.
Treatment: Once a diagnosis of colon cancer is made, staging of the cancer is done. Surgery is the treatment of choice in early stages. In more advanced cancers, adjuvant chemotherapy is also prescribed.
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