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Colon Cancer
If you have been told you have colon cancer, you are not alone. Unfortunately, cancer of the colon has become quite common in our society. Each year, about 155,000 Americans are diagnosed as having colon cancer. For unknown reasons, residents of urban areas of Northern United States have an especially high risk. In fact, about one in 17 (six percent) will develop cancer of the colon in their lifetime. Only lung cancer takes a greater toll.
Colon cancer is a malignant growth that occurs on the inner wall of the colon or rectum. Unfortunately, when colon cancer develops, there may be few, if any, warning symptoms. In some cases, patients in our practice have had no warning signals or symptoms at all. The cancer can be in your colon for years before you notice any symptoms such as a change in bowel habits, rectal bleeding, abdominal pain, thin stools or unexplained weight loss.
Causes of Colon Cancer
The causes are not fully understood. In most cases, colon cancer is triggered by a complex interaction of several different factors. But, regardless of the cause, we have learned that cancer of the colon first develops as a small non-cancerous growth, or polyp (see more about colon polyps below). Some people develop these little “mushroom-like” growths on the inner surface of the intestinal wall. These polyps can occur anywhere in the colon. There are no symptoms. As time goes on, these small polyps may become larger and larger. Eventually, an uncontrolled growth of malignant cells may occur within a polyp. Left untreated, this cancer can penetrate surrounding tissues and spread to other organs.
Certain factors may increase your risk of developing colon cancer. Your chance of developing colon cancer increases with age. Although young adults are occasionally affected, most colon cancer occurs in people after the age of 40. Contrary to some popular beliefs, both men and women are equally affected. Recently, scientists have identified a specific genetic mutation that may contribute to the risk of colon cancer; so heredity is an important risk factor. Other factors such as insufficient fiber (roughage) in our diet may play a role in the formation of colon polyps and subsequent colon cancer.
Diagnosis of Colon Cancer
Colon cancer can be detected by a variety of tests, including digital rectal exam, sigmoidoscopy, colonoscopy, or radiologic tests like CT scan or barium enema. Of these, colonoscopy is the most accurate diagnostic test for colon cancer. All individuals age 50 and over should have a screening test for colon cancer. Some individuals may be at increased risk of colon cancer and they should be screened at an earlier age, including those with a family history of cancer of the colon, rectum, breast or of the female organs, those who have a history of ulcerative colitis (ulcers in the lining of the large intestines), or those with familial polyposis. When colon cancer is found, your prognosis (chance of recovery) and choice of treatment depend on the stage of your cancer (whether it is confined to the inner lining of your colon or if it has spread to other places) and your general state of health.
Stages of Colon Cancer
Colon cancer stage is determined at the time of surgery. Your doctor needs to know the stage of your disease to plan treatment. The Dukes system, developed many years ago, is widely used to classify colon cancer into several stages:
Pre-Cancerous Polyp – Small polyps are not usually cancerous, but will often become malignant as they grow larger over time. In most cases, polyps cause no warning symptoms. Occasionally, a small cluster of cancer cells are found in the top lining of a removed polyp (carcinoma-in-situ). No further treatment is usually needed.
Stage A Colon Cancer – This early cancer is localized to the inner smooth lining of the colon and has not spread through the muscular wall or outside the colon.
Stage B1 Colon Cancer – Cancer cells have invaded the muscular wall but have not broken through.
Stage B2 Colon Cancer – Cancer cells have invaded the muscular wall and has broken through, but they have not yet gone into the lymph nodes.
Stage C1 Colon Cancer – Cancer cells have broken through the outer protective covering and spread to nearby lymph nodes, but have not yet spread to other parts of the body. One to four lymph nodes are involved.
Stage C2 Colon Cancer – Cancer cells have broken through the outer protective covering and spread to nearby lymph nodes, but have not yet spread to other parts of the body. Five or more lymph nodes are involved.
Stage D Colon Cancer – Cancer has spread to other parts of the body. Most often the liver is involved.
Recurrent Colon Cancer – Recurrent disease means that the cancer has come back (recurred) after it has been treated. It may come back in the colon or in another part of the body. Recurrent cancer of the colon is often found in the liver and/or lungs.
Average Five Year Survival
- Stage A – 95 percent
- Stage B1 – 80 percent
- Stage B2 – 60 percent
- Stage C1 – 60 percent
- Stage C2 – 30 percent
- Stage D – less than 5 percent
Treatments for Colon Cancer
There are treatments for all patients with cancer of the colon. The primary goal of therapy is to cure. If cure is not possible, treatment is often still possible to achieve long term control of the illness and to manage the symptoms associated with cancer. Three kinds of treatments are available:
- Surgery – taking out the cancer.
- Radiation therapy – using high-energy x-rays to kill cancer cells.
- Chemotherapy – using special drugs to kill cancer cells.
Your doctors will decide which of these three treatments is best in your particular case.
Colon Polyps & Cancer Prevention
What is a Colon Polyp?
A colon polyp is an abnormal tissue growth which arises on the inner surface of the colon. The large intestine (aka colon) is six feet long and looks like a hollow pipe with a ribbed inner surface. For many reasons, some individuals grow polyps on the inner wall of the colon. Colon polyps are found in one of two shapes; pedunculated, polyps on stems or stalks that look like mushrooms; or sessile, which are flat and sometimes more difficult to find and remove.
Cancer Risk Associated With Colon Polyps
Colon polyps are important since some may turn into colon cancer over time. While not every colon polyp turns to cancer, it is believed that almost every colon cancer begins as a small, non-cancerous polyp. Fortunately, during colonoscopy these polyps can be identified and removed – thus preventing a possible colon cancer.
Different Tissue Types of Polyps
There are basically four types of polyps that commonly occur within the colon:
Inflammatory
Most often found in patients with ulcerative colitis or Crohn’s disease. Often called “pseudopolyps” (false polyps), they are not true polyps, but just a reaction to chronic inflammation of the colon wall. They are not the type that turns to cancer. They are usually biopsied to verify type.
Hyperplastic
A common type of polyp which is usually very small and found in the rectum. They are considered to be low risk for cancer.
Tubular adenoma or adenomatous polyp
This is the most common type of polyp and the one referred to most often when a doctor speaks of colon polyps. About 70 percent of polyps removed are of this type. Adenomas carry a definite cancer risk which rises as the polyp grows larger. Adenomatous polyps usually cause no symptoms, but if detected early they can be removed during colonoscopy before any cancer cells form. The good news is that polyps grow slowly and may take years to turn into cancer. Patients with a history of adenomatous polyps must be periodically reexamined.
Villous adenoma or tubulovillous adenoma
About 15 percent of polyps removed are of this type. This is a much more serious type of polyp that has a very high cancer risk as it grows larger. Larger sessile villous adenomas may require surgery for complete removal. Follow up depends on size and completeness of removal.
Colon Cancer Risk Factors
Family history of colon cancer is a well-recognized risk factor; however, most cases of colon cancer (over 75 percent) are not associated with any risk factors whatsoever. Despite a popular misconception, colon cancer is also an equal opportunity disease – men and women are equally affected. Most cases are diagnosed after the age of 50 and the risk increases with age. The most common symptom of colon cancer is no symptom at all. You could have a polyp, or even an early cancer, growing in your colon right now and feel perfectly fine. There are no symptoms such as pain, bleeding, or change in bowel habits to warn you – until it is too late. By the time that a colon cancer is large enough to change your bowel habits, it may already be too late.
Left undetected, colon cancer eventually penetrates through the outer colon wall and spreads to other organs, most often lymph nodes and the liver. It has been well demonstrated that if colon cancer is caught in the earliest stages the cure rate could be increased to 90 percent. Even better, it has been repeatedly shown that by detecting and removing colon polyps before they develop into cancer, colon cancer can be prevented. Most polyps can now be painlessly removed during a simple 20 minute outpatient “scope” procedure called colonoscopy. To decrease your risk of colon cancer, you need to have any colon polyps found and removed before they become cancerous.
Colon Cancer Screening
To reduce your personal risk, you should undergo an active program of periodic colon checkups before you have symptoms. Just as you would for routine mammograms and prostate exams, you must go see your doctor when you feel well. Here are three different situations that might arise:
If you have symptoms
Screening programs for colon polyps and cancer are designed for patients who have no symptoms. If you have symptoms such as rectal bleeding, altered bowel habit, have been found to have unexplained iron deficiency anemia or a positive test for hidden blood in your stool (Hemoccult), you need to see your doctor for a full investigation, not a screening exam.
Average-risk individuals with no symptoms
Most people fit into this category. For those with no symptoms and no high risk factors, it is recommended that screening begin at age 50. At a minimum, this should include a three day Hemoccult card test for hidden blood in the stool every year and a flexible sigmoidoscopy, “short scope test,” every five years. Recently, it has been shown that this regimen still misses up to 30 percent of colon cancer and even more polyps. This is why most professional health organizations – like the American Cancer Society – now endorse colonoscopy as a primary screening method. There are three advantages to colonoscopy. First is higher accuracy since the entire colon is visualized. Second, with colonoscopy most polyps can be removed when found. And third, if normal, screening colonoscopy need not be repeated as often.
High-risk individual
While we are all at risk, some of us have a higher risk than others because of certain factors in our medical history. Those who fall into a high risk category should also be screened, but at an earlier age such as 40. The appropriate test should be chosen by your physician depending on the circumstances. Most often, a colonoscopy “full scope” exam is done.
If you fall into one of these high risk categories, it is even more important that you begin a regular screening program. High risk factors include:
- Personal history of colon polyps
- Personal history of colon cancer
- Ulcerative or Crohn’s colitis
- Personal history of breast or uterine cancer
- Family history of colon cancer
- Family history of precancerous polyps
Preventing Colon Polyps
There is no reliable way to prevent further colon polyps. However, the risk of polyps can be lowered somewhat by adding more fiber, extra calcium, and 400 micrograms (mcg.) of the vitamin folic acid to the daily diet. Low dose aspirin may also be protective. One study demonstrated a 40 percent drop in the incidence of recurrent polyps by taking an 81 mg baby aspirin daily. Interestingly, higher doses were less protective. But since polyps can not be reliably prevented, periodic colonoscopy exams are recommended.
Preventing Colon Cancer
If you have a history of adenomatous polyps, your risk of future polyps is about 60 percent – and there are usually no warning symptoms that colon polyps are present. With periodic colonoscopy exams, you can maximize your chances that any new polyp will be detected and removed before cancer cells develop. Rarely, a colon cancer may develop between colonoscopy exams. Fortunately, they are usually small and curable by surgery. Periodic colonoscopy can significantly reduce your risk of colon cancer. Ask your doctor when your next colonoscopy should be done.
The Importance of Getting Your Colon Checked
Colon cancer is one of the most curable and preventable forms of cancer. When detected early, more than 90 percent of patients can be cured. Sadly, recent studies show that only about 12 percent of adults ever bother to have a colon examination. As an individual, you can take charge of your health and dramatically reduce your risk of getting colon cancer by having regular examinations before symptoms develop. Following these simple guidelines can keep you healthy to enjoy the good life you have worked so hard to create.