What is Colon Cancer?
Colon Cancer also known as Colorectal Cancer or Large Bowel Cancer includes cancerous growths in the colon, rectum and appendix. Screening for Colon cancer should begin at the age of 40 in healthy adults. 70 to 80 percent of colorectal cancer cases occur in adults without specific risk factors. Colon cancer may affect any racial or ethnic group; however, some studies suggest that Americans of northern European heritage have a higher-than-average risk of colon cancer.
What are Types of Colon Cancer?
The Types of Colon Cancer are as under:
• Adenocarcinomas: These are the most common type of Colon Cancer and originate in glands. They account for about 90-95 percent of all colorectal Cancers and have two subtypes, Mucinous and signet ring cell. The Mucinous subtype comprises about 10-15 percent of Adenocarcinomas while the signet ring cell subtype comprises less than 0.1 percent of Adenocarcinomas.
• Leiomyosarcomas: This type of Colon Cancer occurs in the smooth muscle of the Colon. Leiomyosarcomas account for less than two percent of colorectal Cancers and have a fairly high chance of metastasizing.
• Lymphomas: These are the rare and are more likely to start in the rectum than in the Colon. However, lymphomas that start somewhere else in the body are more likely to spread to the Colon than to the rectum.
• Melanomas: This type of Colon cancer is rare. Usually, it results from a melanoma that started somewhere else and then spread to the Colon or rectum. Melanomas account for less than 2% of colorectal Cancers.
• Neuroendocrine Tumors: This tumor is divided into two main categories: aggressive and indolent.
Colorectal cancer, also called colon cancer or large bowel cancer, includes cancerous growths in the colon, rectum and appendix. Colorectal cancers arise from adenomatous polyps in the colon. These mushroom-shaped growths are usually benign, but some develop into cancer over time. Localized colon cancer is usually diagnosed through colonoscopy.
- Leaking of bowel contents into the pelvis can cause inflammation and infection.
- Change in frequency or character of stool.
- Small-caliber or ribbon-like stools.
- Sensation of incomplete evacuation after a bowel movement.
- Rectal bleeding may be hidden and chronic and may show up as an iron deficiency anemia.
- A family history of colorectal cancer and polyps.
- The presence of polyps in the large intestine.
- Chronic ulcerative colitis.
• Colonoscopy: An endoscope is inserted into the rectum and advanced through the colon, through this the doctor can examine the entire colon.
• Diagnosis is confirmed with a colon biopsy - Stage of disease is confirmed by pathologists and imaging tests, such as computerized tomography (CT or CAT) scans.
• Endoscopic ultrasound and magnetic resonance imaging (MRI) may also be used to stage rectal cancer
• Sigmoidoscopy: In this an endoscope is interested in the rectum and moved through the left side of the colon. It cannot be used to view the middle and right sides of the colon.
• Fecal occult blood test (FOBT) along with Complete blood count (CBC to check for anemia and CT, MRI or PET scans of the abdomen, pelvic area.
The staging of colon cancer helps doctors determine a course of treatment. Staging is done on a scale from 0 to 4, with the higher stages indicating a cancer than has spread more throughout the body.
• Stage 0: In this stage, the cancer hasn’t grown beyond the inner layer of the colon or rectum.
• Stage I: The cancer has spread through the colon’s inner lining, but hasn’t spread beyond the colon wall or rectum.
• Stage II: The cancer has grown through the colon or rectal wall, but hasn’t spread to nearby lymph nodes.
• Stage III: The cancer has invaded nearby lymph nodes but isn’t affecting other parts of the body.
• Stage IV: The cancer has metastasized throughout the body to sites such as the liver, lung, ovaries or the lining of the abdominal cavity.
Surgery is the mainstay of treatment and involves in block removal of diseased segment with adequate margins, surrounding tissue and lymph nodes. The names given to such resections are right hemicolectomy, transverse colectomy, left hemicolectomy, sigmoid colectomy, and subtotal colectomy.
• Polypectomy: If the cancer is found in a polyp (a small piece of bulging tissue), the polyp is often removed during a colonoscopy.
• Local excision: If the cancer is found on the inside surface of the rectum and has not spread into the wall of the rectum, the cancer and a small amount of surrounding healthy tissue is removed.
• Resection: If the cancer has spread into the wall of the rectum, the section of the rectum with cancer and nearby healthy tissue is removed. Sometimes the tissue between the rectum and the abdominal wall is also removed. The lymph nodes near the rectum are removed and checked under a microscope for signs of cancer.
• Pelvic exenteration: If the cancer has spread to other organs near the rectum, the lower colon, rectum, and bladder are removed. In women, the cervix, vagina, ovaries, and nearby lymph nodes may be removed. In men, the prostate may be removed. Artificial openings (stoma) are made for urine and stool to flow from the body to a collection bag.
Radiation therapy is a cancer treatment that uses high-energy beams or other types of radiation to kill cancer cells. There are two types of radiation therapy. External radiation therapy uses linear accelerators outside the body to send radiation toward the cancer. Internal radiation therapy (Brachytherapy) uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type and stage of the cancer being treated.
Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping the cells from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly in the cerebrospinal fluid, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). The way the chemotherapy is given depends on the type and stage of the cancer being treated.
Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells without harming normal cells. Monoclonal antibody therapy is a type of targeted therapy being studied in the treatment of rectal cancer.
Monoclonal antibody therapy uses antibodies made in the laboratory from a single type of immune system cell. These antibodies can identify substances on cancer cells or normal substances that may help cancer cells grow. The antibodies attach to the substances and kill the cancer cells, block their growth, or keep them from spreading. Monoclonal antibodies are given by infusion. They may be used alone or to carry drugs, toxins, or radioactive material directly to cancer cells.
Advantages of Minimally Invasive Laparoscopic Colon Cancer Surgery
• Less surgical trauma, shorter hospitalization, Improved cosmetic results.
• Reduced post operative pain, faster recovery and return to daily activities and normal diet.
• Less postoperative pain killer requirement