Cancer is out of control cell growth. When cells in the large intestine or colon experience uncontrolled cell growth it leads to colon cancer. The large intestine is a 6 feet long hollow tube that runs from the cecum to the rectum. The colon by itself is divided into four parts, the ascending colon, the transverse colon, the descending colon and the sigmoid colon. The muscles lined along the wall of the colon squeeze material as they pass along, extracting water, salt and nutrients. These then move to the rectum to be expelled.
Colon cancer can start with noncancerous, benign tumors in the walls of the large intestine. Some of these adenomatous polyps grow malignant over a period of time turning into cancer.
The rectum forms terminal part of the digestive system. The last 6 inches of the colon constitutes the rectum and anal canal. The anus is the opening of the large intestine outside the body. The main function of the rectum is to store stool and prepare for its evacuation. The rectal wall is made up of three layers the mucosa, muscularis propria and mesorectum. The rectum also constitutes of lymph nodes which are part of the immune system. Adenocarcinoma is the most common form of rectal cancer. Rectal cancer develops from the mucosa. The cancer cells spread to the lymph nodes affecting their surveillance over harmful materials in the body.
- Colon cancer
- Individual above 40 years of age
- Polyps such as adenomas, hyperplastic and inflammatory polyps
- Hereditary nonpolyposis colorectal cancer (HNPCC)
- Genetic abnormalities – mutations in DNA, genetic predisposition of family members
- Diet low in fibre, fruits and vegetables
- Rectum cancer
- Advanced age
- Polyps in the rectum
- Family history of colon cancer
- Inflammatory bowel disease such as ulcerative colitis
- Low fibre, low calcium diet, high in fat
- Personal history of colorectal cancer, cancer of ovary, endometrium or breast
- Having HNPCC or lynch syndrome
- Colon cancer and rectum cancer
- Irritable bowel syndrome
- Iron deficiency
- Alternating diarrhea and constipation
- Blood in stool
- Narrow stools
- Change in consistency of stool
- Pain and cramps in the abdomen – general discomfort of the abdomen such as bloating and gas
- Frequent urges to pass stool
- Weakness and fatigue
- Unexplained weight loss
Some common tests that any colon and rectum cancer patient would undergo are as below.
Colonoscopy; This is an endoscopic test which uses a tube with a light at the end to look for polyps, tumors and associated abnormalities.
Virtual colonoscopy: Images of the inside of the colon are obtained with the use of an x-ray.
Sigmoidoscopy: An endoscope is advanced to view the left side of the colon.
Colon biopsy: A piece of colon tissue is extracted during colonscopy to be examined under the microscope.
Fecal occult blood test: FOBT is done to detect small amounts of blood in stool.
CBC: a complete blood count is done looking for signs of anemia.
Barium enema x-ray: X-rays are taken after special fluid is squirted into the rectum.
Fecal occult blood test: Stool is examined for traces of blood.
Colonoscopy: A long, flexible tube with light is used to check the rectum.
Rectal examination: A physical examination will suggest the presence of any lumps in the rectum.
Proctoscopy: This is also called a rectoscope which is used to examine the anal cavity and rectum. It is only about 25 cm long.
Biopsy: A small sample of tissue is collected and examined in the laboratory for the presence of malignant cells.
Endorectal ultrasound: This device takes pictures of the rectum upon insertion.
MRI: Magnetic resonance imaging uses high definition scan techniques to diagnose the spread of cancer.
A combination of surgery and chemotherapy for colon cancer. Rectal cancer will require radiotherapy in addition.