Colon Cancer: Best way to beat colon cancer is early detection
Every year, approximately one-hundred fifty thousand individuals are diagnosed with this disease and about fifty-thousand individuals die from it.
Colorectal cancer is the third most common cancer in the United States. Every year, approximately one-hundred fifty thousand individuals are diagnosed with this disease and about fifty-thousand individuals die from it. Colorectal cancer affects both men and women although there is a slight predominance of colon cancer in men and rectal cancer in women. While the exact causes of colorectal cancer are unknown, it is believed that there are associations with environmental, nutritional, as well as hereditary factors.
Before colon or rectal cancer develops there is a pre-existing growth known as a polyp. Polyps are extra tissue that grows most often as a projection into the lumen of the colon or rectum. There are basically two types of polyps. The most common is the adenomatous polyp, which is a tubular, or sausage shaped projection and has an approximate fifteen percent chance of turning into cancer. The second is known as a villous adenoma type polyp, which is more a cauliflower-shaped projection, and almost half will eventually develop into cancer. Because of their potential for becoming cancerous, it is extremely important to find and remove polyps early.
The role of heredity
Inflammatory bowel disease (Crohn’s disease and ulcerative colitis) and conditions involving pre-existing polyps increase the risk for colorectal cancer. There are also certain hereditary syndromes that predispose certain individuals to developing colorectal cancer. Familial adenomatous polyposis is a hereditary condition in which there are literally thousands of polyps in the colon and rectum. Essentially all individuals with this hereditary trait will develop cancer by the age of fifty. Another hereditary syndrome is known as Lynch Syndrome. This non-polyposis colorectal cancer syndrome not only increases the risk of colorectal cancer, it also increases the chances that a person will develop other kinds of cancers such as gastrointestinal malignancies and uterine cancer.
Techniques such as a rectal examination and testing the stool for occult blood are helpful in the detection of colorectal cancer but the most effective means is an examination known as a colonoscopy. A colonoscopy is a long thin tube that can be inserted into the rectum all the way through the large intestine with the ability to visualize the lumen of the colon and rectum for polyp formation. It has the extra ability to remove these lesions to test for possible cancer. It is recommended that most adults obtain a colonoscopy at age fifty and every five to eight years thereafter. Some individuals, however, are at higher risk of colorectal cancer and should have colonoscopy examinations on a more frequent basis. This includes women who have a history of breast, ovarian or uterine cancer as they have a higher risk of developing colon cancer. Persons with a sibling, parent, or child with a history of colorectal cancer have a higher predisposition to colorectal cancer due to the previously mentioned hereditary conditions. Men and post-menopausal women with iron deficiency should be immediately screened by a colonoscopy to check for cancer in the colon or rectum that might be causing the iron loss through bleeding. After a polyp has been diagnosed and removed, a repeat colonoscopy should be performed. The timing of the follow up colonoscopy is based on how many polyps are discovered and how aggressive the polyp appears. The time can be as short as a few months for an aggressive villous polyp and between five and eight years for a single low-grade adenomatous polyp. It is important to discuss each situation with the physician performing the colonoscopy.
Early diagnosis is key
No one will argue that the best way to beat the diagnosis of cancer is early detection and surgery. Surgery has been the time-honored method of removing a portion of the colon or rectum in an attempt to cure the patient of cancer. Radiation is also important, especially in the management of rectal cancer. Unlike the colon, the rectum is fixed in location and cannot move causing a greater chance for the cancer to invade surrounding tissue than there is in colon cancer. It is, therefore, helpful to give chemotherapy and radiation prior to surgery to reduce the size of the lesion and hopefully avoid the need for a colostomy. A colostomy is a form of surgery that results in the patient’s large intestine being re-routed to empty into an alternative site from the anus and instead empty into a bag. This procedure may be necessary if not enough rectum can be spared to effectively remove the cancer and, at the same time, reconnect the two ends of the rectum to successfully achieve fecal continence.
Many patients, however, must deal with a state of advanced disease, which requires more than surgical treatment to manage. Even the addition of radiation, which has been shown to improve the outcomes of colorectal cancer, has been unsuccessful in managing the disease once it has spread to sites outside of the colon, known as metastasic cancer. For several years, there have been limited chemotherapy methods available to successfully treat colon cancer. The oldest medication used, flurouracil or 5-FU, is still being used today, and a vitamin derivative known as leucovorin has demonstrated the ability to enhance its effect against colon cancer. However, despite these two medications, only ten to fifteen percent of patients with advanced colon cancer respond to treatment.
Approximately, ten years ago a newer agent known as irinotecan (Camptosar®) was made available. While initially a single therapy, when added to 5-FU and leucovorin the response rate was twice what was seen with the older treatment. Additionally, there was a longer survival period. More recently, a medication known as oxaliplatin (Eloxatin®) was made available. When combined with 5-FU and leucovorin, it demonstrated a response rate in up to one-half of patients with metastatic cancer. This combination of medications has not only been used to treat advanced colorectal cancer, but has also shown superiority in preventing cancer from recurring in patients that are at high risk for cancer returning after surgery. This latter form of therapy is known as adjuvant therapy and is often done with the most effective chemotherapy after surgery to prevent undetectable cancer cells from showing up later in other organs of the body such as the liver. There have also been three non-chemotherapeutic medications recently approved for the treatment of colorectal cancer. These agents, bevacizumab (Avastin®), cetuximab (Erbitux®), and panitumumab (Vectibix®) are known as biologic modifiers. Biologic modifier forms of therapy are known as “targeted” forms of cancer therapy and interact with receptors on the colorectal cancer cells to deprive them of various growth factors that are required for the continued growth of cancer. When these medications have been combined with the older chemotherapeutic medications, there has been an improvement in the response rate with most patients demonstrating a significant reduction in tumor, even at advanced stages. Newer medications, however, bring more and different side effects, which have to be dealt with during treatment. Patients must also deal with a major increase in treatment expense.
Over the last decade, several improvements have been made in the treatment of colorectal cancer; however, treatment that is more effective is still needed. Early indications that combinations of chemotherapy and the previously mentioned targeted therapies will result in improvements in both treating and preventing recurrent colon cancer.
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"Colon Cancer: Best way to beat colon cancer is early detection"
Dr. Fleming earned his MD degree from the University of Louisville, Kentucky, and completed his fellowship at the University of Kentucky which included an externship at the National Cancer Institute.He became a tenured professor in hematology/oncolog...