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Colorectal cancer

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The colon infected with Adenocarcinoma

Colorectal cancer (also called colon cancer) is a cancerous growth in the large intestine (colon), rectum, or appendix. The tumor usually develops into a polyp and if caught early is completely curable. It is ranked as the third most common disease in both males and females in the United States. A recent statistics review in 2009 by the American Cancer Society reported an amount of 106,100 cases for colon cancer and 40,870 cases for rectal cancer in the United States alone. The odds for contracting Colorectal Cancer within a person’s lifespan are about 1 in 19, though. When the risks are combined, the result can be somewhere close to 49,920 deaths. The good news is that due to increased screening processes by hospitals and better care for cancer, the death rate has been winding down within the last two decades. [1]

Types

Main Article: Cancer

Cancer is the uncontrolled growth of abnormal cells that spread throughout the body and attack it. The process of a cancer moving from one place to another is called metastatic. In the digestive system, both the colon and the rectum make up the large intestine. It is here that we find Colon Cancer located inside the wall of the large intestine. There are two types of tumors within the colon that are important to note. First are benign tumors, called polyps. These are non-cancerous tumors which will not harm the colon, but in time, may change into cancers. Because of this, these tumors are considered a minor risk. However dangerous tumors or cancers have more influence. They can easily travel into the bloodstream and affect other areas of the body like the lungs and the liver.[2]

The five different types of Colorectal Cancer are Adenocarcinoma, Leiomyosarcoma, Lymphoma, Melanoma, and Neuroendocrina Tumors. The most common of these is Adenocarcinoma. This disease occurs when a malignant tumor in epithelial tissue rapidly grows within a gland. The two types of Adenocarcinoma are signet ring cell Adenocarcinoma, named for the shape of the cells, and mucinous Adenocarcinoma, named for the large amount of mucous within the cells. In the three muscle layers of the colon, where almost two percent of all Colorectal Cancers take place, we find Leiomyosarcoma. Sarcomas are cancers in connective tissue. They can be made up of bone tumors and soft tissue sarcomas. Symptoms include bleeding and pain in these areas. When dealing with Leiomyosarcoma, early detection is very important because it is a rare disease that metastasizes fast to other areas in the body. The majority of cancerous tumors result from polyps with sizes ranging from two centimeters on up. Anything larger has a thirty to fifty percent chance of becoming malignant. By this time though, the tumor has been present for years, making surgery the only option. Statistics show that by the age of 50, 1 in 4 people have polyps. [3]

Diagnosis

Micrograph of tubular Adenoma in the colon

In order to diagnose Colon Cancer, doctors and physicians must conduct a screening process on patients that range from either a digital rectal examination (DRE), an annual fecal occult blood test, a double-contrast barium enema every 5 to 10 years, a flexible sigmoidoscopy every 5 years, or a total colonoscopy every 10 years. These are recommended for lower risk patients in their 50's with no family history of colon cancer. But African-Americans are offered these choices when they've hit their 40's. [4]

In patients with signs of Colon Cancer and a higher risk level, a biopsy is considered necessary. A biopsy is where the physician goes in, removes a sample of tissue from the colon, and examines it under a microscope for a better diagnosis of the problem. One of the screening processes that was mentioned above, the digital rectal examination (DRE), is done by feeling inside the colon for tumors. And yes, these tumors are large enough where they can be felt by a finger. Another procedure is the fecal occult blood test which checks for the tiniest sample of blood in the waste. Once the cancer is inferred, further testing such as urinalysis, blood tests, and imaging tests is done. [5]

The staging of Colon Cancer is affected by many factors like how far the cancer is spreading throughout the colon and rectum and if the tumors have grown into the intestine wall. This kind of information is essential for determining how dangerous the cancer is or even if prevention is an option. To correctly label which stage the disease is in, the patient must first go through different tests such as biopsies, MRI scans, PET scans, and more. A physician usually uses either pathologic or clinical staging to detect which stage the Colon Cancer is in. This staging system is called the TNM system which stand for three facts. T suggests if the tumors have amassed within the walls of the intestine and if they have spread to areas close by. N indicates whether or not the disease has advanced to the lymph nodes. And M signifies the expansion of the cancer into other organs, most commonly though are the liver and lungs. [6]

Causes

Polyps in the colon

Researchers have come up with 15 different basic causes of Colon Cancer: age, alcohol, diabetes, diet, environment, ethnicity/race, family history, gender, genetics, IBD (Inflammatory Bowel Disease), lack of exercise, obesity, personal history, polyps, and smoking.[7] This disease is not in any way infectious. But a large part of colon cancer comes from diet, a family medical history of cancer, and the number of polyps growing in the intestine. Diet is an essential part of everyday life. Overindulging or even neglecting it can lead to severe consequences. A high fat ingestion can form cancerous chemicals (carcinogens) within the body. That’s why in countries where the intake of fats and junk foods is high, their cancer rates increase, but in countries where the fat intake is low, the rate reduces. Healthy foods such as vegetables can lower the risk and rid the intestine of the harmful substances. [8]

Treatments

The four main kinds of treatment for colorectal cancer are surgery, radiation therapy, chemotherapy, and targeted therapies. Surgery focuses on the colon and the rectum. For the colon, the surgery is most often identified as a colostomy. It is the preferred solution to a cancer found in its early stages. The doctor has the choice to either make one long incision into the abdomen or several small ones. What happens though is that the Colon Cancer is taken out along with a piece of undamaged tissue out of the openings. Then the two ends of the colon are sewn together. The patient’s results are better than expected. For rectal surgery, there are many types that can be used such as polypectomy, local excision, and local transanal resection. These don’t have to be done through incisions but instead with instruments that are placed in the anus. These surgeries are mainly reserved for small cancers still in stage I. [9]

References

External Links