Colorectal cancer develops in the colon (the first 4-5 feet [0.6-0.9 meter] of the big intestine) or the rectum (the last couple of inches of the large intestine).
Colorectal cancer affects the lower component of the digestive tract. It occurs most often in individuals over 50 but might develop in younger adults with a family history of colorectal cancer. Most colorectal cancers develop out of polyps, tissue growths that arise out of the tissue that lines the large intestine. Most polyps are benign, but some undergo changes in their genetic makeup that trigger them to eventually become cancerous.
Colorectal cancer usually develops over a period of a number of years. In many instances the patient has no symptoms but is diagnosed as the result of screening for the disease. About half of patients go to their doctor because they have abdominal pain; a third notice a change in bowel habits; and 15 percent have an obstruction (blockage) in their intestines. In some cases these patients may notice that their bowel movements are unusually thin in shape. As a rule, the larger the cancer and the closer it's to the anus, the more likely the patient is to have noticeable changes in bowel habits.
Colorectal cancer is the fourth most typical cancer in the United States. According to the American Cancer Society (ACS), about 112,000 individuals are diagnosed with colon cancer annually; about 41,000 new instances of rectal cancer are diagnosed each year; and about 57,000 persons die each year from colorectal cancer. According to the World Health Organization (WHO) there are about 940,000 new instances of and 500,000 deaths from colorectal cancer reported worldwide each year.
Colorectal cancer is most common in older adults; the average age at the time of diagnosis is 72. Colon cancer in teenagers or young adults is unusual. Rates are equal for men and women. African Americans appear to have higher rates of colon cancer than members of other racial groups in the United States, but the reasons are unclear. The lifetime risk of developing colon cancer in the United States is about 7 percent. Researchers at the National Cancer Institute have identified several factors that increase a person's risk of colon cancer:
The trigger of most cases of colorectal cancer is the change in normally benign intestinal polyps to cancerous tumors. There are several various types of intestinal polyps, but only two carry a risk of developing into cancers. These two kinds can be removed during screening tests for colorectal cancer. The triggers that trigger some polyps to become cancerous aren't completely understood. In addition to changes in bowel habits, abdominal cramping, and signs of intestinal blockage, patients with colorectal cancer may have the following symptoms:
Doctors might use a number of methods to screen for colorectal cancer. The simplest are a digital rectal examination (DRE) and a fecal occult blood test (FOBT). In a DRE, the physician inserts a gloved finger into the lower component of the rectum to feel for tumors. The FOBT requires the patient to take a kit house from the doctor's office and collect a stool sample, which is then returned to the physician or a laboratory to be tested for occult (hidden) blood. Patients must steer clear of eating rare meat and other foods that can affect the test outcomes before using the kit. Other tests that may be utilized to diagnose colorectal cancer include:
The first step in treating colorectal cancer is known as staging. Staging describes the location of the cancer, its size, how far it has penetrated into healthy tissue, and whether it has spread to other parts of the body. Colorectal cancers are classified into five stages:
In spite of progress in early identification and treatment of colorectal cancer, it remains the third leading trigger of death from cancer in the United States. Prognosis for recovery depends on the stage at which the disease is detected and treated. If it doesn't reappear (recur) within five years, it's considered cured. Stage I, II, and III colorectal cancers are considered potentially curable, but most doctors do not consider Stage IV cancer to be curable.
According to the NCI, 93 percent of colon cancer patients and 93 percent of rectal cancer patients who had been diagnosed with Stage I cancer are still alive five years after diagnosis, but only 39 percent of colorectal cancers are detected at this early stage. The five-year survival rate drops to 8 percent for those diagnosed with Stage IV cancer.
Screening tests for colon cancer in adults over age 50 are good preventive measures. The death rate for colon cancer has dropped since 1990, in component simply because of increased awareness and screening by colonoscopy. Colon cancer can nearly always be caught in its earliest and most curable stages by colonoscopy.
People who have either of the two genes for early colorectal cancer, which could be identified by genetic testing, ought to have colonoscopies during their late teens and have their colons removed when they are in their 20s to prevent getting colorectal cancer. Even though further research is needed to find out how large a role diet plays in the development of colorectal cancer, individuals ought to consider lowering the quantity of fat and increasing the amount of fiber in their diets to lower their risk of this kind of cancer.
It's likely that the survival rate for patients with colorectal cancer will continue to rise over the next few decades. The introduction of more effective screening techniques, the development of new drugs to treat cancer, and further advances in surgical technique ought to all be beneficial.
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