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Colorectal Cancer Prevention

Posted on Nov 16, 2011 05:07am

Dr. Maria Oquendo

Definition: "Colorectal cancer" is cancer that occurs in the colon and/or rectum. These cancers start in the lower digestive tract.

Polyps: The Source of Most Colorectal Cancers
Colorectal cancer almost always develops from a benign growth, which doctors call a "polyp." Cancer may result if the polyp is allowed to remain in the large intestine and grow. ­

Ninety-five percent of colon cancers are thought to originate from a polyp. If polyps are found and removed when they are benign, the person will not develop colon cancer from them. If a benign polyp develops into a malignant tumor, the cancer cells have the ability to leave the original tumor site and travel ("metastasize") to distant locations in the body and invade other organs. Colon cancer is often fatal if the cancer cells have spread unchecked through the lymphatic system or bloodstream to adjacent and/or distant tissues. Colorectal cancer has a strong tendency to metastasize to the liver, which represents the leading cause of death for people with the disease. The lungs are also a frequent site of distant metastasis, followed by the adrenal glands, ovaries in women and then bone.

Early Screenings and Detection are the Keys to Survival and/or Cure
The majority of colorectal cancers would likely have been avoided if the people had only undergone regular and appropriate screenings. Colon cancer kills nearly 60,000 Americans every year and, in adult men, these cancers are second in prevalence only to lung cancer. In women, colon cancer is the third most prevalent cancer, after lung and breast cancer.

It is tragic that the vast majority of the deaths were avoidable if the people had only undergone the relatively minor inconvenience of periodic screenings. Many of those people saw or heard public service announcements urging periodic screening tests, yet didn't act. Don't let that be you or a loved one.

Make sure you know all your risk factors and have screenings, as recommended by the American Cancer Society (ACS) and specialists. You can call the American Cancer Society [(800) ACS-2345] to receive an important and free information kit to help you talk to your doctor about colon cancer testing. This information resource kit includes a brochure outlining the benefits of testing, a list of questions to ask your doctor, and a seven minute informational DVD entitled, "Get Tested for Colon Cancer: Here's How," which reviews the various colon cancer tests as well as test preparation. By taking charge of your health, you can markedly decrease the chance that you will die from colorectal cancer.

Prevalence of Colorectal Cancer by Regions
In the US, the incidence of colon cancer is higher in the North and East, but that is little comfort to those in the West and South who develop colon cancer. Colorectal cancer is more prevalent in Asia and Latin America than it is in Africa. It is not clear whether this is due to genetics, diet or lifestyle, or a combination of these factors.

Colorectal Cancer Treatments - Great Promise for the Future
Current treatment for colorectal cancer does not afford the patient as many options as breast or prostate cancer. A woman with breast cancer can often make a decision whether to have a mastectomy (removal of the entire breast) or lumpectomy (removal of a targeted part of the breast). A man with prostate cancer, depending on the stage of his cancer, can wait and see before deciding on treatment with his doctor or have the prostate removed. With colon cancer, the only choice is to remove the cancer, whether it is confined to a polyp or has spread into the colon wall.

There have been advances in non-surgical treatment of advanced colorectal cancers, like new ways to administer chemotherapy so that people can usually be treated on an outpatient basis. There are also better drugs to treat the nausea caused by chemotherapy, and drugs to increase abnormally low red and white blood cells. Increasing the red blood cells can help restore energy, and increasing the white blood cells can help avoid serious infections.

One of the most exciting breakthroughs has been in the development of a new class of cancer treatment drugs that are called "angiogenesis inhibitors." These choke off development of the blood vessels that cancers need to survive and grow.

Researchers are looking at ways to stimulate the immune system so that it can more effectively challenge colorectal and other tumors. Research also continues into gene therapies, which could not only result in novel ways to treat colorectal cancer, but could enable a defective gene to be corrected before it causes a polyp to become cancerous.

Survival Rates
The newer drugs for more advanced colorectal cancer may be safer and more comfortable. But, the somber reality, as leading Gastroenterologist and co-author of What to Do if You Get Colon Cancer: A Specialist Helps You Take Charge and Make Informed Choices, Dr. Paul Miskovitz , advised CBS Cares, is that someone diagnosed with colon cancer today has comparable chances of survival to someone who was diagnosed in 1975. This further reinforces the crucial role of routine screenings and early detection if cancer is present.

As previously mentioned, colorectal cancer can be prevented through routine screening and polyp removal. If the polyp has become cancerous, early detection and treatment dramatically affects survival. For example, individuals diagnosed with colon cancer in the earliest stage of the disease have a greater than 90 percent chance of beating it. By contrast, another study has shown that with traditional colorectal treatments, only ten percent of patients are alive after five years if the cancer has spread to distant organs. Too many people delay or avoid routine screenings, as evidenced by the fact that only four in ten colon cancers are currently diagnosed at the early, most treatable stage.

The Symptoms and Signs
Many colorectal cancers present no symptoms for a considerable time and, when they do, vague abdominal discomfort is so commonplace patients may ignore it. Colorectal cancer may also be signaled by a change in bowel habits, obstruction of the bowel, blood in the stool and iron deficiency related anemia.

The symptoms of colorectal cancer can also easily be confused with those of non cancerous conditions - for example, diverticulosis, colitis, hemorrhoids and irritable bowel syndrome. Symptoms can provide a clue that someone has colorectal cancer and anyone with serious or persistent gastrointestinal symptoms should see their doctor. But the presence of symptoms does not necessarily mean that someone has colorectal cancer and the absence of symptoms does not mean that colorectal cancer is not brewing. The ACS and experts all agree that routine and periodic screenings are, by far, the most reliable approach to detecting colorectal cancer.

Risk Factors for Colon Cancer:

•Age, which is the most common risk factor. More than 70 percent of cases of colorectal cancer occur in those whose only risk factor is being over the age of 50.
•A personal history of colorectal cancer (having had it before)
•A personal history of colorectal polyps
•A pre-existing bowel condition or disease (such as ulcerative colitis), especially one that causes inflammation of the colon and/or rectum
•Family history due to a gene defect. Evidence is very strong that heredity plays a major role in the development of colorectal cancer. Someone who has a first degree relative with colorectal cancer has a 300 percent greater likelihood of developing colorectal cancer.
•The ACS indicates that Jews of Eastern European descent (Ashkenazi Jews) are at much greater risk of colorectal cancer than the population at large.
•A diet of foods high in fat, especially from animal sources. Frequent charcoal broiled/barbequed foods may also contribute to risk, as do diets lacking plenty of fruits and vegetables. More details on diet are provided below.
•Lack of regular exercise (a minimum of 30 minutes of moderate exercise is recommended on five or more days of the week - consult your doctor before starting to exercise)
•Being overweight (especially around the waist and stomach)--nearly three quarters of Americans are overweight. Few people need more than 2,000 calories a day, yet the daily average is closer to 3,700. Being overweight also triggers a range of other health problems and issues
•Smoking (we knew that smoking causes lung cancer, but smokers are also 30 to 40 percent more likely to die of colorectal cancers)
•Heavy use of alcohol

More on Diet
Dietary habits and nutrition are important in the prevention or cause of colorectal cancer. In summary, a diet high in fresh fruits and vegetables, restrained in calories, alcohol, red meat and animal fat, helps reduce your risk of colorectal cancer. High fat foods and animal proteins should be consumed in moderation. If meat is to be part of the diet, it should preferably be organic and hormone-free. The experts also recommend that it be predominantly white meat, such as chicken and turkey.

The surprise about fiber: Surprisingly, there is not clear scientific proof that a high fiber diet reduces the risk of colorectal cancer. But, the experts recommend a high fiber diet, because it promotes colon health, facilitates regular bowel movements and may well reduce colorectal cancer risks. In addition, fiber helps reduce cholesterol levels.

The truth about broccoli: by contrast to a widely held perception, cruciferous vegetables such as broccoli and cauliflower have not been scientifically proven to have anti-cancer properties. However, the experts strongly recommend inclusion of such vegetables in one's diet, and many believe that they may reduce cancer risks. For example, it has been suggested that proliferation of colon cancer cells has been significantly reduced by concentrations of an element ("sulforaphane") found in cruciferous vegetables.

It has also been suggested that calcium, folate, selenium, fish oil and phytochemicals are important elements in diets that enhance protection against colorectal cancer.

In addition to the above, despite some debate, many experts recommend limiting cured (smoked and pickled) meats because excess consumption could increase risks of colorectal cancer.

The Women's Health Initiative is investigating whether a diet high in calcium and Vitamin D can protect against colorectal cancer. This raises the question whether a diet low in calcium or Vitamin D may increase the risk of colorectal cancer.

For those with colorectal cancer, some experts recommend avoiding sugar, because tumor cells use glucose from the breakdown of sugar as their primary energy source. It has also been suggested that sugars can compromise immune function and trigger increases in insulin that further accelerate cancer cell division.

Screening Tests
There are numerous possible screening tests, which are set out on the ACS's website (www.cancer.org). Many experts believe that the most accurate screening tool is the fiberoptic colonoscopy, which enables your doctor to see the entire length of your colon. Research has shown that the colonoscopy has detected polyps that other tests may miss. If the doctor performing the procedure finds a polyp, s/he will remove it, thereby eliminating it as a potential source of cancer in the future.

Various experts state that for people who have symptoms consistent with colorectal cancer, such as rectal bleeding, iron deficiency anemia, alteration in bowel habits, bowel obstruction or abdominal pain and distension, a colonoscopy (versus other screening options) should be performed to examine the entire colon.

During a colonoscopy, you will be sedated, usually with intravenous medications, to totally relax you. You will usually feel little or no pain due to being sedated and because, as noted by Dr. Miskovitz, the colon cannot experience many of the triggers for pain.

For a colonoscopy to be accurate, your colon must be flushed clean. The doctors have a formidable array of prescription laxatives and enemas to choose from.

As mentioned, there are other screening tests as outlined on the ACS's website and in Dr. Miskovitz's book. But, as noted, none are as sensitive or accurate as the colonoscopy.

Future Screening Tests
It is expected that at some not too distant point, there will be genetic tests to detect risks of colon cancer. For example, future tests may be able to find genes that cause colorectal tumors before the tumors develop. Research is also well underway to develop genetic tests that would diagnose actual colorectal cancer . These include tests to detect DNA changes in the stool.

The virtual colonoscopy has attracted much publicity and also has great promise. The procedure uses computer generated images of the colon from a CT Scan (referred to by many patients as a Cat Scan). The patient is not, however, spared the preparation of taking potent laxatives to ensure that the colon is cleared of all fecal matter, and the body is exposed to some radiation. In addition, if polyps are found, a regular colonoscopy must be performed anyway for their removal.

However, the virtual colonsocopy is less invasive, much less expensive, does not require sedation and takes less time than the fiberoptic colonoscopy.

More research needs to be done on the virtual colonoscopy, which is not a recommended screening test by the ACS at this time.

Lifetime risk in the US of Getting Cancer
In the US, one in four deaths are from cancer. Men have a one in two lifetime chance of developing cancer, while women have a one in three chance. Lifetime risk is the probability that someone will die from cancer over the course of his or her lifetime.

What to do if you or a family member has colorectal cancer
The most important thing is to place yourself in the hands of a knowledgeable doctor and to become as informed as possible about the disease. There are various things you can do to maximize your health. For advice on finding the right doctor and for information on lifestyle and dietary changes that could help your health, CBS Cares has provided a list of suggested websites and books following the interview with Dr. Miskovitz.