Colon and Rectal Cancer
The colon is the part of the digestive system where digested waste material is stored. The rectum is the end of the colon before the anus. Together, the colon and rectum form a long, muscular tube called the large intestine. Tumors of the colon and rectum are growths arising from the inner lining, or mucosa, of the large intestine. Most colorectal cancers start as benign tumors called polyps. Most polyps can be removed during colonoscopy and are not life-threatening. If a polyp grows and progresses to become an invasive cancer, then the tumor can spread to lymph nodes or other organs, such as the liver and lungs. Tumors that spread from the colon or rectum to other organs are called metastases. Metastases are more difficult to treat, but cure is possible in an increasing number of cases with a combination of therapies.
Signs & Symptoms
- Change in bowel habits, including diarrhea, constipation, or a change in the size or consistency of your stool
- Blood in the stool or thick, black stool
- Persistent abdominal discomfort, such as cramps, gas or pain
- A feeling that your bowel doesn't empty completely
- Weakness or fatigue
- Unexplained weight loss
Most people do not experience symptoms until late in the disease course. Therefore, screening for colon and rectal cancer, via colonoscopy, is extremely important. For most patients, colorectal cancer screening should start by the age of 50, but variations do exist depending on several potential risk factors.
Gene mutations that increase the risk of colon cancer can be passed through families, but these inherited genes are connected only to a small percentage of colorectal cancers. Patients who have inherited gene mutations have a significantly higher risk of developing cancer and tumors tend to arise at a younger age. The inherited gene mutation can be detected through genetic testing. If you are concerned about your family's history of colon cancer, then you should talk to your cancer specialist about whether eferral to a genetic counseling service would be appropriate.
Inherited colon cancer syndromes include familial adenomatous polyposis (FAP): FAP is a rare disorder that causes thousands of polyps to develop in the lining of the colon and rectum. People with untreated FAP have a greatly increased risk of developing colon cancer before age 40. FAP patients are also at risk for other tumors, including sarcoma. Also hereditary nonpolyposis colorectal cancer (HNPCC): HNPCC, also called Lynch syndrome, increases the risk of colon cancer and other types of cancer, including endometrial or uterine cancer. Patients with HNPCC tend to develop colon cancer before age 50.
General Treatment Principals
The recommended treatment for colorectal cancer may include surgery, chemotherapy or radiation depending on the stage and location of the cancer at diagnosis. Early stage colorectal cancer and selected patients with metastases will receive recommendations for surgical removal of all tumors. When tumor spread in lymph nodes or the liver is detected, chemotherapy has been proven to be beneficial. As with all cancer types, a comprehensive and individualized assessment is critical to design a treatment plan appropriate for a given patient and given tumor. Treatment plans are formulated by a cancer care team including surgical oncologists, medical oncologists, radiation oncologists, pathologists, and radiologists.
Early stage - Endoscopic Removal
If the cancer is small, localized in a polyp, and in a very early stage, the doctor may be able to remove it completely during a colonoscopy. After the polyp is removed, it is sent to a pathologist, who examines it under the microscope. If a cancerous polyp is completely removed, it may not need further treatment. If invasive cancer is detected, then surgery may be needed to remove that portion of the colon or rectum.
Invasive Cancer - Surgery
If the colon or rectal cancer has grown into or through the wall of the colon, then your surgical oncologist will generally recommend a surgical procedure to remove the part of your colon or rectum. Nearby lymph nodes are also removed and tested for cancer to help determine the prognosis and need for chemotherapy. As discussed below, radiation therapy with or without chemotherapy may be of benefit for certain patients with rectal cancer prior to surgery.
Once the colon is removed, the remaining colon and rectum need to be re-connected, which is referred to as an anastomosis. However, in certain situations an anastomosis may not be safe or feasible. For instance, if the cancer is at the outlet of the rectum, then a colostomy may be necessary. A colostomy involves bringing the colon through the abdominal wall and sewing it open at the skin. An appliance is attached and the intestinal contents empty into a bag. Sometimes the colostomy is only temporary, allowing your colon or rectum time to heal after surgery. But, other times, the colostomy may be permanent. Your surgical oncologist will carefully review these issues with you in consultation prior to arranging for the procedure. When a colostomy is required, specific counseling and training is offered to the patient and family.
Advanced cancer – Surgery and Chemotherapy
In specific cases, when the cancer has spread only to the liver and the patient’s overall health is otherwise fairly good, the doctor may recommend surgery to remove the cancerous lesion (metastasis) from the liver. Chemotherapy be used before or after this type of surgery. In properly selected cases, surgical removal of tumors that have spread to the liver can result in cure. Your surgical oncologist is specially trained in determining which patients are likely to benefit from surgery to remove metastatic tumors.
Laparoscopic Surgery - Colorectal Cancer
All of the surgeries mentioned above can be done with minimally invasive techniques, using a laparoscope. The laparoscopic procedure requires 3 or 4 small incisions, and your surgical oncologist uses a high-definition monitor and camera to visualize the inside of the abdomen. This method reduces pain levels after surgery and length of stay in the hospital. Minimally invasive surgery is not appropriate for all cancer cases. The approach offering the highest chance for cure with the greatest level of safety is chosen in each individual case.