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Cancer Types - Colorectal Cancer
The colon is the the large intestine. It has four sections.
The first section is called the ascending colon. It extends upward on the right side of the abdomen.
The second section is called the transverse colon since it goes across the body to the left side.
There it joins the third section, the descending colon, which continues downward on the left side.
The fourth section is known as the sigmoid colon because of its S-shape.
The sigmoid colon joins the rectum, which, in turn, joins the anus, or the opening where waste matter passes out of the body.
What is colorectal cancer?
Colorectal cancer is malignant cells found in the colon or rectum. The colon and the rectum are part of the large intestine, which is part of the digestive system. Because colon cancer and rectal cancers have many features in common, they are sometimes referred to together as colorectal cancer. Cancerous tumors found in the colon or rectum also may spread to other parts of the body.
Excluding skin cancers, colorectal cancer is the third most common cancer in both men and women. It is estimated by the American Cancer Society that 153,760 colorectal cancer cases are expected in 2007. The number of deaths due to colorectal cancer has decreased, which is attributed to increased screening and polyp removal.
What are the symptoms of colorectal cancer?
The following are the most common symptoms of colorectal cancer. However, each individual may experience symptoms differently.
People who have any of the following symptoms should check with their physicians, especially if they are over 50 years old or have a personal or family history of the disease:
- a change in bowel habits such as diarrhea, constipation, or narrowing of the stool that lasts for more than a few days
- rectal bleeding or blood in the stool
- cramping or gnawing stomach pain
- decreased appetite
- vomiting
- weakness and fatigue
- jaundice - yellowing of the skin and eyes
The symptoms of colorectal cancer may resemble other conditions, such as infections, hemorrhoids, and inflammatory bowel disease. It is also possible to have colon cancer and not have any symptoms. Always consult your physician for a diagnosis.
What are the risk factors for colorectal cancer?
Risk factors may include:
A risk factor is anything that may increase a person's chance of developing a disease. It may be an activity, such as smoking, diet, family history, or many other things. Different diseases, including cancers, have different risk factors.
Although these factors can increase a person's risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop the disease, while others develop disease and have no known risk factors. But, knowing your risk factors to any disease can help to guide you into the appropriate actions, including changing behaviors and being clinically monitored for the disease.
- age
Most people who have colorectal cancer are over age 50, however, it can occur at any age. - diet
Colorectal cancer is often associated with a diet high in fat and calories, and low in fiber.
- polyps
Benign growths on the wall of the colon or rectum are common in people over age 50, and are believed to lead to colorectal cancer. - personal history
People who have had colorectal cancer, as well as ovarian, uterine, or breast cancers, have a slightly increased risk for colorectal cancer. - family history
People with a strong family history of colorectal cancer or polyps in a first-degree relative (in a parent or sibling before the age of 60 or in two first-degree relatives of any age), have an increased risk for colorectal cancer. - ulcerative colitis
People who have ulcerative colitis, an inflamed lining of the colon, have an increased risk for colorectal cancer. - obesity
- physical inactivity
- high-fat and/or low-fiber diet
- alcohol consumption
- diabetes
What causes colorectal cancer?
The exact cause of most colorectal cancer is unknown, but the known risk factors listed above are the most likely causes. Less than 10 percent of colorectal cancers are caused by inherited gene mutations. People with a family history of colorectal cancer may wish to consider genetic testing. The American Cancer Society suggests that anyone undergoing such tests have access to a physician or geneticist qualified to explain the significance of these test results.
Persons with a family history of colorectal cancer may wish to consider genetic testing. The American Cancer Society suggests that anyone undergoing such tests have access to a physician or geneticist qualified to explain the significance of the results.
Prevention of colorectal cancer:
Although the exact cause of colorectal cancer is not known, it is possible to prevent many colon cancers with the following:
- diet and exercise
It is important to manage the risk factors you can control, such as diet and exercise. Eating more fruits, vegetables, and whole grain foods, and avoiding high-fat, low-fiber foods, plus exercising appropriately, even small amounts on a regular basis, can be helpful. - drug therapy
Some studies have shown that low doses of nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, and estrogen replacement therapy for post-menopausal women may reduce the risk of colorectal cancer. Discuss this with your physician. - screenings
Perhaps most important to the prevention of colorectal cancer is having screening tests at appropriate ages. Because some colorectal cancers cannot be prevented, finding them early is the best way to improve the chance of successful treatment, and reduce the number of deaths caused by colorectal cancer.The following screening guidelines can lower the number of cases of the disease, and can also lower the death rate from colorectal cancer by detecting the disease at an earlier, more treatable stage.
Methods of screening for colorectal cancer:
Screening methods for colorectal cancer, for people who do not have any symptoms or strong risk factors, include the following:
- digital rectal examination (DRE) - a physician or healthcare provider inserts a gloved finger into the rectum to feel for anything unusual or abnormal.
- fecal occult blood test - checks for hidden (occult) blood in the stool. It involves placing a very small amount of stool on a special card, which is then tested in the physician's office or sent to a laboratory.
- fecal immunochemical test (FIT) - a test that is similar to a fecal occult blood test, but does not require any restrictions on diet or medications prior to the test.
- One of the following:
- sigmoidoscopy - a diagnostic procedure that allows the physician to examine the inside of a portion of the large intestine, and is helpful in identifying the causes of diarrhea, abdominal pain, constipation, abnormal growths, and bleeding. A short, flexible, lighted tube, called a sigmoidoscope, is inserted into the intestine through the rectum. The scope blows air into the intestine to inflate it and make viewing the inside easier.
- colonoscopy - a procedure that allows the physician to view the entire length of the large intestine, and can often help identify abnormal growths, inflamed tissue, ulcers, and bleeding. It involves inserting a colonoscope, a long, flexible, lighted tube, in through the rectum up into the colon. The colonoscope allows the physician to see the lining of the colon, remove tissue for further examination, and possibly treat some problems that are discovered.
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- barium enema with air contrast (Also called a double contrast barium enema.) - a fluid called barium (a metallic, chemical, chalky, liquid used to coat the inside of organs so that they will show up on an x-ray) is given into the rectum to partially fill up the colon. An x-ray of the abdomen shows strictures (narrowed areas), obstructions (blockages), and other problems.
| Screening Guidelines for Colorectal Cancer |
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Colorectal cancer screening guidelines for 2007 from the American Cancer Society for early detection include:
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Diagnostic procedures for colorectal cancer:
In addition to a complete medical history and physical examination, diagnostic procedures for colorectal cancer may include the following:
- digital rectal examination (DRE) - a physician or healthcare provider inserts a gloved and lubricated finger into the rectum to feel for anything unusual or abnormal. This test can detect cancers of the rectum, but not the colon.
- fecal occult blood test - checks for hidden (occult) blood in the stool. It involves placing a very small amount of stool on a special card, which is then tested in the physician's office or sent to a laboratory.
- sigmoidoscopy - a diagnostic procedure that allows the physician to examine the inside of a portion of the large intestine. A short, flexible, lighted tube, called a sigmoidoscope, is inserted into the intestine through the rectum. The scope blows air into the intestine to inflate it and make viewing the inside easier.
- colonoscopy - a procedure that allows the physician to view the entire length of the large intestine. It involves inserting a colonoscope, a long, flexible, lighted tube, in through the rectum up into the colon. The colonoscope allows the physician to see the lining of the colon, remove tissue for further examination, and possibly treat some problems that are discovered.
- barium enema - a fluid called barium (a metallic, chemical, chalky, liquid used to coat the inside of organs so that they will show up on an x-ray) is given into the rectum to partially fill up the colon. An x-ray of the abdomen shows strictures (narrowed areas), obstructions (blockages), and other problems.
- biopsy - a procedure in which tissue samples are removed (with a needle or during surgery) from the body for examination under a microscope; to determine if cancer or other abnormal cells are present.
- blood count - to check for anemia (a result of bleeding from a tumor).
What are the stages of colorectal cancer?
When colorectal cancer is diagnosed, tests will be performed to determine how much cancer is present, and if the cancer has spread from the colon to other parts of the body. This is called staging, and is an important step toward planning a treatment program. The National Cancer Institute defines the following stages for colorectal cancer:
| Stage 0 (Cancer in Situ) | The cancer is found in the innermost lining of the colon. |
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| Stage I (also called Dukes’ A colon cancer) | The cancer has spread beyond the innermost lining of the colon to the second and third layers and the inside wall of the colon. The cancer has not spread to the outer wall of the colon or outside of the colon. |
| Stage II (also called Dukes’ B colon cancer) | The cancer has spread outside the colon to nearby tissue. However, the lymph nodes are not involved. |
| Stage III (also called Dukes’ C colon cancer) | The cancer has spread to nearby lymph nodes, but has not spread to other organs in the body. |
| Stage IV (also called Dukes’ D colon cancer) | The cancer has spread to other parts of the body, such as lungs. |
Treatment for colorectal cancer:
Specific treatment for colorectal cancer will be determined by your physician based on:
- your age, overall health, and medical history
- extent of the disease
- your tolerance for specific medications, procedures, or therapies
- expectations for the course of this disease
- your opinion or preference
After the colorectal cancer is diagnosed and staged, your physician will recommend a treatment plan. Treatment may include:
- colon surgery
Often, the primary treatment for colorectal cancer is an operation called a colon resection, in which the cancer and a length of normal tissue on either side of the cancer are removed, as well as the nearby lymph nodes. - radiation therapy
Radiation therapy is the use of high-energy radiation to kill cancer cells and to shrink tumors. There are two ways to deliver radiation therapy, including the following:- external radiation (external beam therapy) - a treatment that precisely sends high levels of radiation directly to the cancer cells. The machine is controlled by the radiation therapist. Since radiation is used to kill cancer cells and to shrink tumors, special shields may be used to protect the tissue surrounding the treatment area. Radiation treatments are painless and usually last a few minutes.
- internal radiation (brachytherapy, implant radiation) - radiation is given inside the body as close to the cancer as possible. Substances that produce radiation, called radioisotopes, may be swallowed, injected, or implanted directly into the tumor. Some of the radioactive implants are called “seeds” or “capsules."
Internal radiation involves giving a higher dose of radiation in a shorter time span than with external radiation. Some internal radiation treatments stay in the body temporarily. Other internal treatments stay in the body permanently, through the radioactive substance loses its radiation within a short period of time. In some cases, both internal and external radiation therapies are used.
- chemotherapy
Chemotherapy is the use of anticancer drugs to treat cancerous cells. In most cases, chemotherapy works by interfering with the cancer cell’s ability to grow or reproduce. Different groups of drugs work in different ways to fight cancer cells. The oncologist will recommend a treatment plan for each individual. Studies have shown that chemotherapy after surgery can increase the survival rate for patients with some stages of colon cancer. Chemotherapy can also help relieve symptoms of advanced cancer.
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