Mesothelioma Info

Colorectal cancer is unchecked cell growth in the large intestine (colon) or rectum that results in tumors that can spread to other parts of the body. The colon and rectum make up the end of the 30-foot-long digestive tract. The colon is the 5 feet of muscular tubing near the end that receives digested nutrients from the small intestine and passes non-absorbed waste on to the rectum (the last 8 to 10 inches of the tract), where they are held before they are expelled through the anus.
Figure 1. Colorectal cancer
Colorectal cancer is unchecked cell growth in the large intestine (colon) or rectum that results in tumors that can spread to other parts of the body.
Colorectal cancer can arise anywhere in the colon or rectum. The majority of cases (60%) occur in the lower part of the colon or rectum. A quarter of cancers show up in the rectum. Colorectal cancer tends to develop slowly over many years, and starts out as precancerous lesions or polyps. When detected and treated early enough, colorectal cancer is usually curable. Unfortunately, however, most cases are detected after the cancer has spread, which is why colorectal cancer is the second-leading cancer killer in the U.S.
Causes

Colorectal cancer occurs when abnormal cells in the lining the colon or rectum proliferate out of control. The cancer may originate on the surface of the intestinal lining or on a bud on a stalk that protrudes from the intestinal wall (polyp). Colorectal polyps are very common. As many as 40% of Americans have them by age 50. Most polyps remain noncancerous (benign), but about 5 to 10% go on to become cancerous (malignant) if they are not removed. As the cancer grows, it begins to invade the intestinal wall. Without treatment, it can infiltrate nearby tissues and lymph nodes and spread through the blood to the liver and other organs.
Symptoms

In its earliest stages, colorectal cancer has few or no symptoms. Therefore, it is extremely important to undergo routine screening tests beginning at age 50. More advanced colorectal cancer can produce changes in bowel habits and bloody stools. If you experience constipation, diarrhea, or pencil-thin stools for more than 10 days, you should see your doctor. Likewise, blood (bright red or black in appearance) in your stool warrants medical attention, even though it does not necessarily mean that you have cancer. Hemorrhoids or rectal tears might be the culprit. Bowel movements also can become discolored after you eat certain foods, or after you take iron supplements. Abdominal pain, bloating, cramps, and gas are other possible symptoms of colorectal cancer. Loss of appetite and weight loss may occur as well.
Table 1. Signs and Symptoms of Colorectal Cancer

Blood (bright red or black) in stoolWeight lossAppetite lossFatigueCramps, bloating, gas painsDiarrhea and/or constipationNarrow stools or other changes in bowel habitsRisk Factors

Colorectal cancer can strike men and women of all ages, but occurs most frequently in older adults. The number of colorectal cancer cases begins to rise in people starting around age 40, and peaks after age 70. If you have colorectal cancer in your family, or if you have already had colorectal cancer or have adenomatous polyps (a hereditary condition that results in hundreds of polyps in the colon or rectum), your risk goes up, and the age at which the risk begins is earlier. Other bowel conditions such as ulcerative colitis and Crohn's disease increase the likelihood of colorectal cancer.
Lifestyle factors such as diet and activity level play a role in colorectal cancer. A diet high in calories and fat—animal fats in particular—may increase colorectal cancer risk; however, this has been questioned. This conclusion comes from the fact that colorectal cancer is not nearly as common in Asia and in other parts of the world where diets tend to be low in animal fat and high in fiber. Colorectal cancer predominantly affects people in affluent Western nations who typically eat less fiber and more animal fat. Race appears to have no influence. Japanese people who live in the U.S. are more likely to get colorectal cancer than those who live in Japan. A lack of exercise and obesity are also associated with higher rates of colorectal cancer.
Diagnosis

A fecal occult blood test (FOBT) can reveal blood that may be hidden in your stool—one of the earliest signs of colorectal cancer. FOBTs are easy to do, and are noninvasive. One common method involves analyzing samples from three consecutive bowel movements. You collect the samples at home, and bring them to your doctor or mail them directly to a laboratory. It is best to use test kits supplied by your doctor rather than ones purchased over-the-counter. The latter are not as reliable.
Doing an FOBT involves placing a bit of stool on a chemically treated paper that changes color after development when blood is present. A positive finding does not mean you have cancer—you may have hemorrhoids or an infection. If you take aspirin or other NSAIDs, this could produce a positive result as well. Likewise, eating certain foods (rare beef, raw broccoli, bean sprouts, cauliflower, oranges, apples, bananas) could be confounding the results. Also, iron supplements may lead to a misreading of the test as falsely positive.
A positive FOBT warrants a more thorough investigation of your colon and rectum. Sigmoidoscopy, colonoscopy, barium enemas, and digital rectal exams are tools that may be used. Sigmoidoscopy and colonoscopy use a flexible, lighted viewing tube (endoscope) inserted through the anus that enables careful inspection of the colon. Sigmoidoscopy only permits examination of the lower two feet of the colon only, whereas colonoscopy offers a complete view of the colon and the rectum. About 70% of colorectal cancers occur in areas that can be seen during sigmoidoscopy. Both procedures can be done on an outpatient basis. A sedative can minimize discomfort during a colonoscopy, the more involved of the two tests.
Before a sigmoidoscopy or colonoscopy, you will be asked to consume a liquid diet and take a laxative, or have an enema to empty your bowel. If your doctor finds suspicious lesions, he or she will take a sample for analysis. If polyps are detected during a colonoscopy, they will likely be removed at this time.
Because a sigmoidoscopy does not provide a complete picture of the colon, it should be accompanied by a barium enema with air contrast study of the upper colon and a digital rectal exam (DRE). Barium is a chalky white substance that can reveal colon abnormalities on an x-ray. For such a test, you will be given a barium enema followed by air to expand your colon, and then x-rays will be taken. Your doctor can feel for rectal abnormalities during a DRE, which involves inserting a gloved, lubricated finger into the anus. DREs are usually done as part of routine pelvic exams for women and prostate checks for men. Unfortunately, a substantial proportion of small to medium-sized polyps, and some cancers, will be missed on a barium enema.
Virtual CT colonoscopy is an experimental test that is less invasive than a traditional colonoscopy. It involves an enema followed by air to expand the colon, followed by a CT scan. Computer images provide three-dimensional views of the colon. This technique is more comfortable than a regular colonoscopy, but may not be as effective for detecting cancer because the doctor is unable to take biopsies. As more experience is gained with this test, it may become an alternative to a first-step screening test. At present, relatively few centers have experience with this, and the test remains insensitive for small polyps or cancers.
If cancer is found, your doctor will determine its grade and stage to help guide decisions regarding your treatment Grade and stage indicate how aggressive your cancer is and whether/how far it has spread. This information is essential for plotting an appropriate treatment plan, which will involve surgery, radiation therapy, chemotherapy, or a combination of these approaches.
A biopsy of the lesion can reveal the grade—how “aggressive” or how different the cells look compared with normal cells. The stage will fall between 0 and 4, depending on the extent of cancer spread within the intestinal wall, whether cancer has invaded neighboring tissues, and whether cancer has spread to the lymph nodes, liver, lungs, or elsewhere in the body. A stage 0 cancer has not yet become invasive; a stage 4 cancer has spread to the liver or some other non-colonic site.
Prevention and Screening

Regular screening can detect colorectal polyps and cancer very early on—before symptoms are apparent, and when cancer can be prevented or cured. Colorectal cancer frequently begins as polyps. Not all polyps turn cancerous, but there is no way to tell which ones will and which ones will not. Therefore, if growths are found, it is best to have them removed, which is usually done at colonoscopy. Colorectal cancer is more than 90% curable when found and treated early, but less than a third of Americans follow the screening protocol necessary for this to happen. Although risk factors are important for determining which type of tests should be administered and how often they should be done, 70% to 80% of colorectal cancers are found in people of average risk. This is why the American Cancer Society (ACS) recommends that all Americans undergo a yearly DRE beginning at age 40. At age 50, annual FOBTs and a sigmoidoscopy every 5 years are advised. The ACS also recommends a colonoscopy every 10 years or a double-contrast barium enema every 5 for people in this age group, although this more aggressive approach is usually reserved for higher risk individuals. Screening should be done earlier and more frequently if you have risk factors for colorectal cancer. Having colorectal polyps, ulcerative colitis, Crohn's disease, or a personal or family history of colorectal cancer puts you at increased risk. A family history of breast or endometrial cancer also slightly elevates your risk.
Following a healthy diet and exercise regimen may help lower your risk for colorectal cancer. Aim for a low-fat, high-fiber diet. Try to get at least five servings of fruits and vegetables and six servings of other plant-based foods such as cereals, breads, rice, pasta, and beans every day. Keep red meat and other foods containing animal fat to a minimum. Some research suggests that taking a multivitamin that has folic acid lowers colorectal cancer risk. Other studies have found that boosting calcium intake through supplements or low-fat dairy products could also lower risk.
It is also important to achieve and maintain a healthy weight. Research shows that excess fat can alter metabolism in such a way that increases the growth rate of cells in the colon and rectum. A moderate exercise regimen—half an hour of physical activity most days of the week—can help you keep your weight under control. These dietary recommendations are best followed on a lifelong basis. Altering one's diet after the appearance of colonic polyps has very little effect on limiting future polyp occurrence.
Taking aspirin and other NSAIDs seems to play a role in preventing colorectal cancer. Several population studies have consistently found that people who take aspirin on a regular basis are at much lower risk for acquiring colorectal cancer and pre-cancerous polyps. However, clinical trials have not explored this issue, nor has an appropriate preventative dose been determined.
Treatment

Urgent Care

Call your doctor if you experience rectal bleeding or a change in bowel habits that lasts longer than three weeks. Seek immediate medical attention if you are unable to pass stool.
Drug Therapy

Your doctor is the best source of information on the drug treatment choices available to you.
Other Therapies

Your doctor may wish to administer radiation before surgery to shrink your tumor or after surgery to kill any lingering cancer cells. If you have rectal cancer, radiation could be the primary treatment. Radiation therapy uses high-energy rays to destroy cancer cells. It is used most frequently for rectal cancer; sometimes as the main therapy. When given before surgery, it can reduce the size of the tumor and make it easier to remove. Post-surgery, it can destroy cancer cells that may have been missed. It can also ease the pain, bleeding, and intestinal blockages that occur with advanced cancers.
Radiation from an outside source is the most common way to deliver the therapy, which is typically given five days a week for many weeks. Each treatment lasts for a few minutes, and is a lot like having an x-ray. Some doctors are experimenting with implanting radioactive seeds directly into and around a tumor. Internal radiation is not often used for people with colorectal cancer. If you have a colon tumor that cannot be removed, your doctor may wish to try this approach. The side effects of radiation—fatigue, skin irritation, loss of appetite, nausea, and diarrhea—are usually temporary.
Therapies that boost the patient's immune system are currently being explored. Immunotherapy uses the body's natural defenses to fight cancer. A variety of clinical trials involving different immune-enhancing therapies for colorectal cancer are underway. Some are looking at whether boosting the immune system overall with certain drugs might help. Others are exploring vaccines that stimulate the immune system to recognize and destroy abnormal cellular changes that occur with colorectal cancer. These are still in the experimental phases, and none have yet been shown to be effective in a clinical trial.
Surgery

If you have colon cancer, your doctor will recommend surgery to remove it. Very early colon cancers (i.e., stage 0 and 1) can be removed through a colonoscope, obviating the need to cut into the abdomen. Laparoscopic surgery for colon cancer is controversial. This minimally invasive procedure involves making very small incisions in the abdomen and using special instruments to remove the cancerous parts of the colon and nearby lymph nodes. Laparoscopic procedures are considerably less traumatic, and have a shorter recovery period than standard surgical procedures, but the risk of cancer recurrence is higher. Some experts think the laparoscopy should be reserved for very old patients in whom easier recovery outweighs risk of recurrence in terms of importance.
The majority of patients with colon cancer undergo segmental resection. For this procedure, the cancerous part of the colon plus some of the healthy tissue surrounding it and nearby lymph nodes are removed, and the healthy sections are rejoined. The amount taken depends on the size and location of the tumor. A surgical resection can cure you. If your cancer has spread or is incurable, the procedure may prolong your life or make you more comfortable.
Before a bowel resection, you will be asked to follow a special diet and fast the preceding night. The surgery will be performed under general anesthesia, and may take several hours depending on the extent of your cancer. If cancer has spread to other areas, such as the liver or lungs, it may be removed at this time.
If your cancer is located so close to the anus that your doctor is unable to rejoin the remaining healthy sections, you will need a colostomy. For a colostomy, your colon will be brought outside your body through your abdominal wall, and stitched to your skin. A bag will be attached to collect intestinal wastes. A temporary colostomy may be needed in the event of an emergency resection. Permanent colostomies are needed in about 15% of cases.
Hospital recovery typically takes 3 to 10 days. During this time, you will have a catheter inserted in your bladder, and you will need to be fed through an intravenous line or a tube in your stomach or bowel. The doctor will frequently ask if you have had gas or a bowel movement, a good sign that your bowel is starting to function normally again. At this point, you can resume regular eating. Once out of the hospital, you should be able to do light activities in as little as a week, but should avoid heavy exertion and lifting for 4 to 6 weeks.
If you have rectal cancer, your doctor will probably recommend surgery to remove it. Surgery is usually the main treatment for rectal cancer, though some cases may be managed with radiation alone. Local excision can remove superficial lesions from the inner layers of the rectum. But in some cases, a resection is necessary. Early cancers can be removed with instruments inserted through the anus without an abdominal operation. More extensive procedures are needed for advanced cancers. If the tumor is in the upper part of the rectum, the remaining healthy segments can be re-attached and stool eliminated normally. If the rectal tumor grows too close to the anus, a colostomy will be needed.
Alternative Medicine

Shark cartilage has been touted as a cancer remedy, but evidence for the claim is slim. Assuming that sharks don't get cancer, some researchers began studying various substances from these fish and found that shark cartilage (the elastic material that makes up a shark's frame as bone makes up a human frame) blocks blood vessel formation. Because tumors need blood and oxygen to grow, scientists hypothesized that shark cartilage might help fight cancer. Other cancer-fighting properties in shark cartilage have been reported, and some animal studies have shown promise for the supplement. But human studies of shark cartilage for cancer have failed to show any real benefit, and it cannot be recommended until positive results are reported.
Prognosis

Your long-term outlook depends on which stage your cancer was in when it was discovered and how well you responded to your treatments. If your cancer was caught early, your chance of cure is high. In general, the five-year survival rate for those whose colorectal cancer is limited to in the intestinal lining is 90%. When cancer penetrates intestinal muscle, the rate is 70-80%. When cancer invades the lymph nodes, the rate drops to 40-50%.
Follow-up

If you have had colorectal cancer, you will need to see your doctor on a regular basis. If your treatments were successful, your doctor will want to see you annually to make sure your cancer has not returned. Follow-up visits generally include physical and rectal examinations, colonoscopy, an abdominal CT scan, and blood tests that reveal tumor markers or anemia. If any of these tests is suspicious, your doctor may request imaging studies such as x-rays, CT scans, and MRIs. If no cancer is found after 3 years, you may only need to see your doctor once every 3 years for colonoscopy. This is because new cancers can develop in the colons of people after resection.