Definition of colon cancer: Cancer that forms in the tissues of the colon (the longest part of the large intestine). Most colon cancers are adenocarcinomas (cancers that begin in cells that make and release mucus and other fluids).
Definition of rectal cancer: Cancer that forms in the tissues of the rectum (the last several inches of the large intestine closest to the anus).
Colon cancer is a disease in which malignant (cancer) cells form in the tissues of the colon.
The colon is part of the body’s digestive system. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of the esophagus, stomach, and the small and large intestines. The first 6 feet of the large intestine are called the large bowel or colon. The last 6 inches are the rectum and the anal canal. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).
Gastrointestinal stromal tumors can occur in the colon.
Health history can affect the risk of developing colon cancer.
Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Talk with your doctor if you think you may be at risk. Risk factors include the following:
- A family history of cancer of the colon or rectum.
- Certain hereditary conditions, such as familial adenomatous polyposis and hereditary nonpolyposis colon cancer (HNPCC; Lynch Syndrome).
- A history of ulcerative colitis (ulcers in the lining of the large intestine) or Crohn disease.
- A personal history of cancer of the colon, rectum, ovary, endometrium, or breast.
- A personal history of polyps (small areas of bulging tissue) in the colon.
Possible signs of colon cancer include a change in bowel habits or blood in the stool.
These and other symptoms may be caused by colon cancer. Other conditions may cause the same symptoms. Check with your doctor if you have any of the following problems:
- A change in bowel habits.
- Blood (either bright red or very dark) in the stool.
- Diarrhea, constipation, or feeling that the bowel does not empty all the way.
- Stools that are narrower than usual.
- Frequent gas pains, bloating, fullness, or cramps.
- Weight loss for no known reason.
- Feeling very tired.
- Vomiting.
Tests that examine the colon and rectum are used to detect (find) and diagnose colon cancer.
The following tests and procedures may be used:
- Physical exam and history: An exam of the body to check general signs of health, including checking for signs or disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- Digital rectal exam: An exam of the rectum. The doctor or nurse inserts a lubricated, gloved finger into the rectum to feel for lumps or anything else that seems unusual.
- Fecal occult blood test: A test to check stool (solid waste) for blood that can only be seen with amicroscope. Small samples of stool are placed on special cards and returned to the doctor or laboratory for testing
Colonoscopy
A procedure to look inside the rectum and colon for polyps, abnormal areas, or cancer.
A colonoscope is inserted through the rectum into the colon. A colonoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer.
Treatment for colorectal cancer depends on the stage at which cancer was discovered. Early stage colorectal cancer is best treated with surgery. Approximately 95% of Stage I and 65-80% of Stage II colorectal cancers are curable with surgery. Rectal cancer however, may require additional radiation therapy to minimize the risk of recurrence. Advanced stage (Stage III and Stage IV) often consists of a combination of therapies, including: surgery, chemotherapy, and radiation.
Although staging of your cancer is an important indication of the type of treatment you may receive, it is not the sole factor in defining your specific treatment. All treatment decisions at Tulane Comprehensive Cancer Clinic are determined on an individual basis based on discussions with surgical medical and radiation oncologists, because no two cancers and no two people are identical. Several other factors are considered in your individual assessment, including your age, general health, family history of cancer, other medical conditions, and whether it is a new cancer or one that has recurred. Since each patient’s situation is unique, you should ask your doctor for a detailed explanation of the implications of the stage of your cancer chemotherapy.
Cancer Chemotherapy
Chemotherapy uses drugs to destroy cancer cells. Chemotherapy can be used to destroy cancer cells after surgery, to control tumor growth or to relieve symptoms of colon cancer. Your doctor may recommend chemotherapy if your cancer has spread beyond the wall of the colon or if your cancer has spread to the lymph nodes. In people with rectal cancer, chemotherapy is typically used along with radiation therapy.
Radiation Therapy
Cells that might remain after surgery, to shrink large tumors before an operation so that they can be removed more easily, or to relieve symptoms of colon cancer and Radiation therapy uses powerful energy sources, such as X-rays, to kill any cancer rectal cancer. Radiation therapy is rarely used in early-stage colon cancer, but is a routine part of treating rectal cancer, especially if the cancer has penetrated through the wall of the rectum or traveled to nearby lymph nodes. Radiation therapy, usually combined with chemotherapy, may be used after surgery to reduce the risk that the cancer may recur in the area of the rectum where it began.
Targeted Drug Therapy
Drugs that target specific defects that allow cancer cells to proliferate are available to people with advanced colon cancer, including bevacizumab (Avastin), cetuximab (Erbitux) and panitumumab (Vectibix). Targeted drugs can be given along with chemotherapy or alone. Targeted drugs are typically reserved for people with advanced colon cancer. Some people are helped by targeted drugs, while others are not. Researchers are working to determine who is most likely to benefit from targeted drugs. Until then, doctors carefully weigh the limited benefit of targeted drugs against the risk of side effects and the expensive cost when deciding whether to use these treatments.
For more information:
http://www.cancer.org/cancer/colonandrectumcancer/index
http://www.cancer.net/cancer-types/colorectal-cancer
http://www.medicinenet.com/colon_cancer/article.htm
http://www.cdc.gov/cancer/colorectal/
http://www.cancer.gov/cancertopics/types/colon-and-rectal
