Colon cancer is an overgrowth of tissues in the colon or the large intestine and is commonly found in the humans. Sometimes it is also considered as colorectal cancer as rectum is a continuation of the colon. The colon cancer develops gradually from small polyps in the beginning to fully grown lumps of cancer. These polyps are commonly known as adenomatous polyps which are usually benign clusters of cells. These polyps are small in size and remain asymptomatic for some time or main show a few symptoms over a time period.
Causes of Colon Cancer
Although the actual cause is still not known; but like most of the cancers, colon cancer is also a result of the uncontrolled and the uncoordinated growth or division of the cells of the colon. These cells may remain at the same site forming the clumps or may enter the bloodstream to travel to rest of the body parts. The precancerous growths called polyps usually progress into cancer. The Familial Adenomatous polyposis which is characterized by occurrence of several polyps in the intestine may also gradually develop into colon cancers. Heredity is another known cause which may lead to transfer of genetic mutation to other generations with a risk to develop cancer. Lynch syndrome may also lead to the risk of developing colon cancer.
Signs and Symptoms of Colon Cancer
People suffering from colon cancers may suffer from the following symptoms:
- The cancer may lead to change in the bowel habits which may include diarrhea or constipation or altered consistency of stools.
- There may be a tint of blood in the stools or sometimes frank blood in stools may be noticed.
- People may also feel pain or discomfort persistently along with cramps or gas.
- There might be a feeling of incomplete emptying of the bowel.
- Fatigue or weakness
- Sudden loss of weight.
Some people may not experience any symptoms in the early stages but these symptoms may appear gradually with different size and severity of the disease. The cancer of colon may be classified into 4 stages according to its severity as follows:
Stage I.When the cancer has grown not beyond the mucosal wall of the colon or rectum
Stage II.When the cancer has grown across the wall of the colon and the nearby tissues, except the lymph nodes.
Stage III.When the cancer has affected the nearby lymph nodes but not the other distant organs
Stage IV. When the cancer has affected other organs as well
Diagnosis of colon cancer
Cancers of the colon can be usually diagnosed with the help of colonoscopy which involves examining the colon with a long and thin optical tube attached with a camera to view the internal surface of the large intestine. If a colon cancer is suspected, a small section of tissue may be obtained from the colon for the purpose of biopsy. Other method of diagnosis includes CT scan for forming multiple images of the colon.
Treatment of Colon Cancer
The treatment of colon cancer includes the 3 basic treatment options for any cancer: surgery, chemotherapy and radiation.
- Surgical removal: early stage cancers or small polyps can be removed by endoscopic mucosal resection during colonoscopy or by laparoscopic surgery. Invasive colon cancer can be treated by partial colectomy or sometimes removal of affected lymph nodes as well. Temporary or permanent colostomy may also be performed in case when cancer is at the opening of the rectum. In case of severe cancers, surgeons may relieve the signs and symptoms by removing the lesions surgically.
- Chemotherapy: it includes the use of drugs to prevent the spread of cancer to the lymph nodes or the other body organs, or to prevent its recurrence.
- Radiation therapy: it is usually used in combination with chemotherapy after the surgical removal in order to prevent its recurrence.
- Targeted drug therapy: the lately used methods of treatment include use of drugs likepanitumumab (Vectibix),bevacizumab (Avastin), cetuximab (Erbitux) and regorafenib (Stivarga) to target the specific defects.