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COLO - RECTAL CANCER
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COLO - RECTAL CANCER
Cancer of the lower digestive tract is very common in the U.S.A, and was historically treated with drastic operations. The patient was often left with a bag on the abdomen to drain stool (a "colostomy"). Unfortunately, the death rate from the cancer was high even with these debilitating surgeries, and new research has shown some more effective ways of managing (and often curing) these cancers. These newer treatments commonly allow maintainance of normal toilet activity by avoiding colostomy. They are just as, if not more effective in producing a cure.
It is crucial to be well eductated to make the proper choices in dealing with colon or rectal cancer. This can literally make the difference between life and death. Being knowledgable gives you the peace-of-mind to know you have done everything possible to fight this disease successfully.
What is Colo-Rectal Cancer?
The cells lining the inner colon and rectum are called "columnar epithelial cells," and also "goblet cells" which secrete mucous to help keep the stool soft. These cells invaginate (fold upon themselves) to form glands, and the type of cancer which most commonly arises from glands is called "adenocarcinoma." As with all cells in the body, the production of new cells lining the intestine is under tight control from the "genes" within each cell, which are themselves composed of the basic genetic material "DNA." In the growing child, the cells divide quickly to form the enlarging intestines, but in the adult cells are only produced to replace those that die of injury or lost to old age. Colon cancer, like any cancer, starts in a single cell . This cell loses control of it's division and then starts to reproduce in a haphazard, uncontrolled manner to form a "tumor." A tumor merely means a swelling, it can be caused by most anything and is not necessarily cancer. A "benign" tumor, also called a "polyp" within the intestines, only grows within it's local area; it cannot go to other areas of the body and so is not cancer. In contrast, a "malignant" tumor is capable of spreading to any area of the body, it is cancer. This process of spread is called "metastasis." Sometimes previously benign tumors can become malignant over time, this process is called "malignant degeneration" and happens in some polyps. Most polyps, however, will never become cancerous. If cancer does arise and is not effectively treated, the will ultimately spread to other crucial body areas and kill the patient. Advanced colon cancer most often kills by causing anemia, debility, infection, and organ failure. This is why it is critical to diagnose and treat any cancer as early as possible, when the chances for successful treatment are highest.
How common is Colo-rectal Cancer?
Colo-rectal cancer is the third most most lethal cancer in the United States, after lung and breast cancer, with 156,000 new cases and 68,000 deaths in 1999 . Of these deaths, approx. 58,750 are from colon cancer and 10,000 are from rectal cancer. Over their lifetimes, 7% of Americans will develop a colo-rectal cancer at some point. The disease is rare (3% of cases) in those under 40 years old. Men are effected slightly more often than women. The disease is more common in the Western World than in Asia. However, if an Asian person moves to the United States, there chance for getting colon cancer increases. In the United States, the highest risk areas are in the Northeast, and the lowest in the Southwest. The incidence of colo-rectal cancer has been going up over the past 3 decades, but the death rate peaked in 1985, owing to earlier detection and better treatments.
How and Where Does Colo-rectal Cancer Start?
It usually starts from a polyp, which is a protrusion of gut tissue which starts as being non- cancerous. These polyps are often screened for, and may be removed before becoming cancerous. If a polyp is less than 1 cm. across, it has only a 1% chance of being cancerous, but if it is larger than 2 cm. across, the chance of cancer rises to almost 50% . Polpys become much more common as we grow older, over 80% of people over 70 years old have at least one polyp. The risk for developing Colo-rectal cancer is increased with:
1) A high fat, low fiber diet. (The NCI noted 40 studies making this association). This is thought due these foods taking longer to pass through the colon, thus allowing more contact with cancer-inducing chemicals ("carcinogens") in these foods. In contrast, high fiber foods stimulate the colon to move food through quickly, and lessen the chance for polyps to form. Colo-rectal cancer is rare in societies that eat mostly fruits and vegetables, and the vitamins in these (especially vitamins A and E ) may be protective. This is a reason that colon cancer is rarer in the Far East where less dietary fat is consumed.
2) Family Predisposition Certain cancers, namely colo-rectal, breast, uterine and ovarian, tend to occur with alteration of the same genes, known as the "family cancer syndrome" genes. While not all people with these inherited genes get cancer, many do. Around 15% of new patients with colo-rectal cancer have close family members with disease.
3) Hereditary syndromes causing multiple polyps in the digestive tract. For example, 100% of Familial Polyposis patients will get colon cancer if the colon isn't removed. In this condition, there are thousands of polyps in the colon, and the more polyps, the greater the chances for a cancerous one to arise. Other rarer syndromes include "Turcot's," where there are associated brain tumors, and "Gardner's," with tumors in other glandular areas. The Peutz- Jeghers syndrome has lots of polyps throughout the intestinal tract, but they are the more benign type ("hamartomas") and the risk of cancer is low.
4) Age older than 40 years . Younger patients rarely develop this cancer, but if so it tends to be very aggressive. The average patient is 60 years old. This goes along with more polyp formation as we get older, and a greater risk that the polyps will be abnormal ("dysplastic") with age.
5) Inflammatory bowel disease, especially ulcerative colitis (less in Crohn's). The risk of developing colon cancer with ulcerative colitis is about 2% per year. In these conditions, there are many more new intestinal cells being produced to replace those lost through inflammation and infection. The more new cells formed, the greater chance that a cancerous one will arise.
6) Radiation Exposure to the abdomen or pelvis may trigger cancer, but usually not for 10 to 50 years after the exposure. The chance of developing cancer from medical X-rays is remote, estimated at about 6 cases per million X-ray procedures. Moreover, the type of cancer induced by radiation is more likely to be a muscle, bone or cartilage tumor ("sarcoma") than the much more common adenocarcinoma of the colo-rectum.
7) Chemical Exposure ("carcinogens") from foods or even from substances produced within our own bodies. It is thought that eating burnt foods, nitrites, and various artificial additives and preservatives may increase cancer risk, but it is hard to prove. The more fats a person eats, the more bile salts their gall bladder releases, and these have been shown to promote polyp growth. It is very hard to eat a pure, clean diet in America.
8) Possible link to depression, with decreased immune system response. Generally, digestive diseases have been considered by psychiatry to result from "anger turned inward." It is now known that normal people's immune systems are able to recognize and destroy tiny cancer cells before they can spread. In the diseased or depressed person, the immune system does not function efficiently and may allow cancer to start. The flip side is that a good positive attitude helps cancer patients live longer and better. Over 50% of cancers are in the rectum or lowest portion of the colon, the sigmoid. In the colon, 25% of cancers are in the ascending portion, 15% in the transverse portion, and 10% in the descending portion. There has been a shift toward the right colon in the past 2 decades.
How can Colo-Rectal cancer be Prevented?
Increased intake of fiber and Vitamin A, and decreased fat in the diet, are thought protective against bowel cancers. For high risk patients, early detection with occult blood tests and periodic colonoscopy and polyp removal is appropriate. For the rare very high risk patient, who has a genetic disease with multiple polyps, prophylactic removal of the colon may be reasonable since almost 100% of these patients will get colon cancer if it isn't removed. Any prolonged rectal bleeding, whether bright and red or black and tarry must be promptly evaluated, and not just ignored as "hemorrhoids."
What are the Symptoms of Colo-rectal Cancer?
The most common symptom is blood in the stool . This is bright red with cancers of the rectum and sigmoid colon, but is usually thick, black, and "tarry" if the cancer is higher up in the digestive tract. This type thick tarry blood is called "melena," and is the result of the blood being partially digested. It is important to note that most blood found in the stool is not due to a cancer, but rather a benign condition such as ulcers, bleeding polyps, hemorrhoids or fissures in the anal canal. Nonetheless, persistant bleeding must never be ignored. With any prolonged slow bleeding, It is common to develop Iron-Deficiency anemia, manifested by weakness and paleness, and eventual shortness of breath. This bleeding may be so slow that the patient doesn't even realize it, yet comes to their doctor with anemia. Subsequent evaluation of this bleeding may prove a bowel cancer.
Changes in the stool are often seen. These are chronic diarrhea in many right-sided colon cancers, and pencil-thin stools in left sided or rectal cancer. A feeling of incomplete emptying of the rectum, called "tenesmus" is frequent with rectal cancer.Pain usually occurs only later in the disease, usually due to painful spasms of the intestine, and invasion of the cancer into nerves. If a cancer grows large enough, it can completely block the bowel, causing "bowel obstruction." Symptoms of total bowel obstruction include no appetite, no bowel movements, abdominal pain, bloating, vomiting. This is an emergency and must be treated with surgery. Every colo-rectal surgeon has had the experience of first detecting cancer at the time of this emergency surgery. Other common later ymptoms include abdominal masses as the tumor grows, weight loss, liver enlargement and bone pain with spread to those organs. Nearly all untreated colon cancer will eventually spread to the liver, since this follows the course of the draining (venous) blood from the colon . The liver provides an ideal spongy, blood-rich area for cancer "seeds" to implant and grow. Less than 10% of colon cancers spread to the brain, but a change in motor skills, judgement, memory or sensation is occasionally the first sign noted. Sometimes, the first sign is spread of the cancer to another body area, and the original tumor cannot even be found (but may have been from the digestive tract). This "cancer of unknown origin" is a well described clinical entity, and a different topic.
How is Colo-rectal cancer Detected and Evaluated?
It may be detected before symptoms with screening, or after symptoms cause the patient to seek medical care:
1) Screening: Has been shown to lower the death rate from this cancer, especially if polyps are detected, and removed with a "polypectomy." Patients at higher risk, such as having a family history of colon cancer, should get colonoscopy (where a doctor puts a tube up into the colon to examine it under light anesthesia) every 3 years after age 40. The regular-risk patients should get a yearly digital rectal exam and test for occult blood in the stool every year after age 40, along with their annual physical exam. "Occult blood" in the stool means quantities to small to be noted by the patient; a specially treated card ("guiac test") allows the doctor to smear a little stool on this card, and use a developer which turns the stool smear blue if blood is present. To be sure the test is "negative" (i.e. normal-- no blood present) several consecutive stool samples should be tested. If any test shows blood, the fuller evaluation (below) must be done.
The Cancer Group Institute's materials explain, in plain English, the definition, frequency, risk factors, symptoms, evaluation, historic and latest effective treatments for colo-rectal cancer, as well as screening information. We describe treatments including surgery, radiation, and chemotherapy, and their results. We tell you everything you need to know to help you make the right choices today for a colon or rectal cancer problem.
