Colon and Rectum
The colon is a tunnel that is approximately 5 – 6 feet long. The first 5 feet is the large intestine or colon which connects to the rectum which is approximately 6 inches long. At the other end of the rectum is the anus. The main role of the intestines is to change waste into stool. Food will take about 3 – 8 hours to travel through the large intestine after consumption. During this time, nutrients will be absorbed into the body, while the residual will be removed as waste.
Colorectal cancer
Colorectal cancer is the third most common form of cancer in both men and women in the Western world, with 105,000 new patients being diagnosed annually in the United States. The risk of colorectal cancer increases for people over 50 years old. Most colorectal cancer starts out as adenomatous polyps or benign tumors. In Thailand, cases of colorectal cancer are on the rise in both men and women.
High Risk Group
- People with personal history or family history of adenomatous polyps or hereditary colorectal cancer syndrome.
- Patients who suffer from inflammatory bowel disease or Crohn’s Disease should receive cancer screening test at an earlier age.
- People with familial history of colorectal cancer, such as parents, siblings, or children have 2 – 3 times higher risk of cancer than the general population.
“In reality, approximately 80% of newly diagnosed colorectal cancer patients are not in the risk group.”
Risk Factors
Research shows that lifestyle behaviors contribute to the risk of colorectal cancer:
- High consumption of fatty food and read meat
- Low consumption of fruits and vegetables
- Consumption of high caloric food
- Lack of or little exercise
- Obesity
- Heavy drinkers and smokers
Stages of Colorectal Cancer
- Stage 0 (cancer in situ) – the cancer is in the mucosa or the lining of the colon.
- Stage I – The cancer is in the second and third layers of the colon wall, but has not invaded through to the muscle wall. This stage is also known as Dukes’ A.
- Stage II – The cancer has spread through the muscle layer, but not the lymph nodes. This stage is also known as Dukes’ B.
- Stage III – the cancer has spread through the muscle layer and the lymph nodes, but has not metastasize to other organs. This stage is also known as Dukes’ C.
- Stage IV – the cancer has spread to other organs (such as liver or lungs). This stage is also known as Dukes’ D.
Tell – tale Signs
In the early stages, the patient may not show any signs of bleeding or bloody stool. The stool may change its shape (long thin line) and there may be abdominal cramping.
Rectal cancers tend to have different symptoms than colon cancer. The symptoms include bloody stool, cycling between constipation and diarrhea without any known cause, size of stool has changed, and abdominal pain with or without excretion. If the mass is large enough, it might affect nearby organs, such as urinary incontinence or pain in the perineum or rectum.
Diagnosis
Patients may receive any of the following procedures to determine the stage and spread of cancer:
- Endoscopy to examine the lower gastrointestinal tract
- Some patients may be diagnosed by X-ray using Barium enema
- Blood test to find carcinoembryonic antigen (CEA) (blood marker for colorectal cancer)
- Chest X-ray
- Computer X-ray of the abdominal and pelvic regions
Other than the aforementioned techniques, CT scans, MRIs and endoscopic ultrasound (EUS) may be able to determine the extent of the tumor.
Colorectal Cancer Treatment
Patients with Stage 0 and I Colorectal Cancer
- Surgical removal only
Patients with Stage 2 and 3 Colorectal Cancer
- Patients are at risk of recurrence and should receive radiation therapy and chemotherapy either before or after surgery. Although most patients will have their mass removed, there is a 50 -60% chance of recurrence. Chemotherapy will reduce the risk.
Patients with Stage 4 Colorectal Cancer
- Surgical removal can be performed in conjunction with radiation therapy with or without chemotherapy. Some patients may need surgical management of metastatic cancer to other organs, such as the liver or ovary.
Surgery
Surgical removal can be performed on the affected area of the colon. As for rectal cancer, which is located in the pelvis region, the surgeon will need to use a specific technique to cu through nearby tissue to remove the mass.
Patients who have a very large mass that cannot be surgically removed should receive radiation therapy and chemotherapy to reduce the mass prior to surgical removal. This method is known as down staging.
