Colorectal Cancer Facts
Description of Colorectal Cancer
The term “colorectal cancer” refers to cancers that occur in the lower part of the digestive system – primarily in the colon or rectum. The body’s solid waste is stored in the colon; the rectum is the end of the colon adjacent to the anus. Together, the colon and rectum form the large intestine, a long, muscular tube. Colorectal cancer, is also called colon cancer or large bowel cancer, includes cancerous growths in the colon, rectum and appendix. It is the third most common form of cancer and the second leading cause of cancer-related death in the Western world. Colorectal cancer causes 655,000 deaths worldwide per year, including about 16,000 in the UK, where it is the second most common site (after lung) to cause cancer death.[1] Many colorectal cancers are thought to arise from adenomatous polyps in the colon. These mushroom-like growths are usually benign, but some may develop into cancer over time. The majority of the time, the diagnosis of localized colon cancer is through colonoscopy. Therapy is usually through surgery, which in many cases is followed by chemotherapy.
Tumors of the colon and rectum are growths that form on the inner wall of the large intestine. Benign tumors are called polyps. A polyp may look like a wart when it is small, and when it grows it may resemble a cherry on a stem.
Polyps of the colon and rectum almost always are benign. Usually they produce no symptoms, although they may cause painless rectal bleeding or bleeding that cannot be seen by the naked eye. Polyps of the large intestine routinely are removed surgically, and are not life threatening.
If benign polyps are not removed from the large intestine, they can become malignant over time. Most cancers of the large intestine are believed to develop from polyps. >Colorectal cancer can invade and damage nearby tissues and organs. Cancer cells also can break away and spread to other parts of the body, such as the liver and lungs, where new tumors form. The spread of cancer from its point of origin to distant organs is called metastasis. Once metastasis has occurred in colorectal cancer, a complete cure of the cancer is unlikely.
Colon Cancer Statistics
Colorectal cancer is a relatively common cancer, ranking second in the United States. In 2005, approximately 145,290 new cases of colorectal cancer (71,820 men and 73,470 women) will be diagnosed in the United States. Researchers estimate that more than 56,000 people will die from the disease; slightly more men than women, accounting for ten percent of all cancer deaths in 2005. Blacks in America have the highest rate of incidence; Hispanics have the lowest rates. The cumulative lifetime risk for the disease is one in 20. Excluding skin cancers, colorectal cancer is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that about 108,070 new cases of colon cancer (53,760 in men and 54,310 in women) and 40,740 new cases of rectal cancer (23,490 in men and 17,250 in women) will be diagnosed in 2008.
Colorectal cancer is extremely curable when caught early. As the disease progresses, survivability rates slide downward. The death rate (the number of deaths per 100,000 people per year) from colorectal cancer has been dropping for more than 20 years. There are a number of likely reasons for this. One is that polyps are being found by screening and removed before they can develop into cancers. Screening is also allowing more colorectal cancers to be found earlier when the disease is easier to cure. In addition, treatment for colorectal cancer has improved over the last several years. As a result, there are now more than 1 million survivors of colorectal cancer in the United States.
Clolrectal Cancer Diagnosis and Colon Cancer Detection
Today’s early detection strategies mean that health professionals are catching colorectal cancers in their very early stages, when they are highly treatable. A simple screening procedure called a colonoscopy can find polyps before they ever have a chance to become cancerous.
Colorectal cancer can take many years to develop and early detection of colon cancer greatly improves the chances of a cure. Therefore, screening for the disease is recommended in individuals who are at increased risk. There are several different tests available for this purpose.
In many cases, colorectal cancers occur without symptoms, making colonoscopy the best way to check for early signs of colorectal cancer. In addition, there are some warning signs to watch for, including very dark or bright red blood in the stool; unexplained weight loss; persistent exhaustion; changes in the shape, frequency, and consistency of stools; or pain, cramps or bloated feelings in the stomach.
In a colonoscopy, a doctor inserts a lighted tube into the rectum and colon to look for polyps or other changes such as inflammation or bleeding. Research has shown that removing polyps during a colonoscopy significantly decreases the risk that colorectal cancer will develop.
Other commonly used detection methods include a digital rectal exam to feel for any abnormalities by hand, a test to examine the stool for traces of blood, or an X-ray.
Advances in screening technology, and publicizing the importance of routine screenings, have helped to reduce significantly the number of deaths from colorectal cancer.
If signs of cancer are detected using the methods listed above, a doctor will likely take a biopsy – a small tissue sample from the affected area – in order to diagnose definitively or rule out cancer. Polyps removed during a colonoscopy often are biopsied.
Doctors may also use blood tests to look for other common signs of colorectal cancers, such as a high level of a protein called CEA (carcinoembryonic antigen), or an increased number of red blood cells. Neither proves colorectal cancer definitively, however. A Fecal occult blood test (FOBT) tests for blood in the stool. Two types of tests can be used for detecting occult blood in stools i.e. guaiac based (chemical test) and immunochemical. The sensitivity of immunochemical testing is superior to that of chemical testing without an unacceptable reduction in specifity.
If cancer is diagnosed, it is critical for doctors to determine first whether the cancer is limited to the colon or rectum, or if it has begun to metastasize to other areas of the body. This evaluation typically involves using advanced imaging to allow doctors to see a three-dimensional picture of the inside of the body. Any spread of cancer to other organs, such as the lungs or liver, must be discovered or ruled out before an appropriate treatment plan can be created for a patient.
Virtual colonoscopy is being developed as a new way to detect polyps and colon cancer early, without a traditional colonoscopy. This procedure uses a series of X-rays and computer technology to produce images of the colon. It is still being tested to gauge its effectiveness, and is not a standard method of screening at this time.
Colorectal Cancer Prevention and Risk
Many uncontrollable factors, such as age, family medical history, or past cancer diagnoses, increase colorectal cancer risk. Age is by far the greatest risk factor. However, there are lifestyle choices one can make to lessen risk.
People who smoke more than 20 cigarettes a day are 250 percent more likely to develop polyps than are nonsmokers who otherwise share the same risk factors (e.g., age, family history). People who drink alcohol have an 87 percent greater likelihood of having polyps compared to nondrinkers. Those who both smoke and drink are 400 percent more likely to develop polyps compared to their peers who neither smoke nor drink. Clearly, avoiding smoking and excessive drinking are critical to preventing colorectal cancer.
Eating a healthy diet also appears to be an important factor in preventing colorectal cancer. Most doctors stress that a diet rich in fruits, vegetables, fiber and legumes can decrease risk. It appears that the phytochemicals in some vegetables have preventive properties. Diets laden with red meat and excessive saturated fat, conversely, seem to increase colorectal cancer risk.
There is increasing evidence that diets high in calcium and folic acid can reduce the risk of colorectal cancer, as well. Research is underway to gather more data supporting this association. Researchers are also studying nonsteroidal anti-inflammatory drugs (NSAIDs) and daily consumption of aspirin to see if these medications can help to prevent colorectal cancer.
Scientists are also improving their understanding of how being overweight and sedentary can contribute to an increased risk of colorectal cancer. So far, evidence shows that maintaining a healthy weight and integrating regular exercise into one’s daily routine can have a measurable positive impact.
The WCRF panel report Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective finds the evidence “convincing” that alcoholic drinks increase the risk of colorectal cancer in men.
The NIAAA reports that: “Epidemiologic studies have found a small but consistent dose-dependent association between alcohol consumption and colorectal cancer even when controlling for fiber and other dietary factors. Despite the large number of studies, however, causality cannot be determined from the available data.”
“Heavy alcohol use may also increase the risk of colorectal cancer” (NCI). One study found that “People who drink more than 30 grams of alcohol per day (and especially those who drink more than 45 grams per day) appear to have a slightly higher risk for colorectal cancer.” Another found that “The consumption of one or more alcoholic beverages a day at baseline was associated with approximately a 70% greater risk of colon cancer.”
One study found that “While there was a more than twofold increased risk of significant colorectal neoplasia in people who drink spirits and beer, people who drank wine had a lower risk. In our sample, people who drank more than eight servings of beer or spirits per week had at least a one in five chance of having significant colorectal neoplasia detected by screening colonoscopy.”. This proves that if you were thinking of getting a Beer Gift Basket for someone you love that you could actually be doing them a favor. Just be sure that the beer baskets are enjoyed in moderation.
Other research suggests that “to minimize your cancer risk, it’s best to drink in moderation.”
On its colorectal cancer page, the National Cancer Institute does not list alcohol as a risk factor: however, on another page it states, “Heavy alcohol use may also increase the risk of colorectal cancer”
Drinking may be a cause of earlier onset of colorectal cancer.
Latest Colon Cancer Research
Educating the public about the value of screening has helped to reduce death rates from colorectal cancer. On the research front, doctors are developing better drugs and new detection tools as ways to offer patients more accurate screening, improved care and enhanced survivability. In addition, researchers continue to improve their understanding of how genetics and lifestyle choices impact colorectal cancer risk.
One of the most promising developments in colorectal cancer has been the development of new drugs for late-stage colorectal cancer patients. These targeted therapies aim for a specific cell in the body, unlike other forms of chemotherapy which do not discriminate between cancerous and healthy cells. Before the advent of targeted drugs, there were few options for late-stage colorectal cancer patients.
Recently, the U.S. Food and Drug Administration approved two new drugs – Avastin™ (bevacizumab) and Erbitux™ (cetuximab) – which work to keep tumors from getting certain inputs they need in order to grow. Avastin™ blocks blood flow to the tumor, starving it of essential oxygen and nutrients. This landmark concept, called anti-angiogenesis, was first proposed by Dr. Judah Folkman of Harvard University. The mode of action of Erbitux™ is to interfere with cellular signals that encourage tumors to grow. Doctors now (August 2005) have six drugs to use in the fight against advanced colorectal cancers and, in some cases, to double the survival rate.
Scientists are learning more about some of the inherited and acquired changes in DNA that cause cells of the colon and rectum to become cancerous. Recent discoveries of inherited genes that increase a person’s risk of developing colorectal cancer are already being used in genetic tests to inform people most at risk.
Advances in understanding how these genes work are expected to eventually lead to new drugs and gene therapies to correct these gene problems. Early phases of gene therapy trials are already in progress.
Work also is underway to develop methods that leverage the body’s own immune system to fight cancer. These “cancer vaccines,” trick the immune system to recognize the cancer as foreign, and encourage the body to mount a fight against it.
Chemoprevention is the use of natural or man-made chemicals to lower a person’s risk of developing cancer. Researchers are testing whether certain supplements, minerals (such as calcium), and vitamins (such as folic acid or vitamin D) can lower colorectal cancer risk.
Some studies have found that people who take multivitamins containing folic acid (also known as folate), vitamin D supplements, or calcium (through either diet or supplements) may have a lower colorectal cancer risk than people who do not. Research to clarify the possible benefits of these and other substances, such as selenium and curcumin, is now under way.
Finally, doctors are combining several types of drugs and chemotherapies to increase the effectiveness of the overall chemotherapy.
Colorectal Cancer Treatment
Surgery is the frontline treatment for early-stage colorectal cancer – that which has not yet spread. Doctors remove the tumor, and possibly surrounding lymph nodes. In rare cases, patients may need to have a colostomy, in which doctors create a hole in the colon for waste to pass through into a bag, which is worn externally by the patient.
For more advanced cancers that may have metastasized, doctors use surgery, chemotherapy and radiation in various combinations. Sometimes chemotherapy is administered before surgery to shrink the tumor. Chemotherapy and radiation are used to kill any traces of cancer that were not removed surgically.
Treatment for advanced colorectal cancer will involve combinations of multiple treatment approaches, aimed primarily at extending life.
Many clinical trials are testing new chemotherapy drugs or drugs that are now used against other cancers (such as cisplatin or gemcitabine). Other studies are looking at ways to combine drugs already known to be active against colorectal cancer, such as irinotecan or oxaliplatin, to improve their effectiveness. Newer studies are also looking at adding targeted therapies such as cetuximab or bevacizumab to chemotherapy as part of adjuvant therapy. Still other studies are testing the best ways to combine chemotherapy with radiation therapy and/or immunotherapy.
Colorectal Cancer Resources
National Colorectal Cancer Research Alliance
1-213-240-3900
http://www.eifoundation.org/national/nccra/splash/index.html
National Cancer Institute
1-800-4-CANCER
www.cancer.gov
Colon Cancer Alliance
1-877-422-2030
www.ccalliance.org
American Cancer Society
1-800-ACS-2345
www.cancer.org