Large intestine (colon)
Large intestine (intestine) is called colon in medicine. The beginning of the colon, which continues after the small intestines, is in the lower right pit of the abdominal cavity. This part of the colon is called the cecum and its small extension is the "appendix". The colon starting from here extends from the right side of the abdominal cavity to under the liver (ascending colon), bends to the left under the liver and extends to the upper left corner of the abdominal cavity (horizontal colon), bends here again and extends to the lower left corner of the abdominal cavity (descending colon), from here to the abdominal cavity. It resembles the letter "S" towards the right-back-middle-bottom of the cavity (sigmoid colon) and finally forms the last part (rectum) that goes to the anus.
The rectum part of the colon consists of some of the other parts. Because they show differences, their cancers are named separately as colon cancer and rectum cancer, or they are mentioned together under the name of colorectal cancers.
Colon cancer and frequency
Colorectal cancers. They are very common tumors in adults. In general, it constitutes about 13% of all cancers in industrialized countries. According to World Health Organization figures, the highest frequency is in a region of the USA, with 34/100,000 in men and 27/100,000 in women. The lowest frequency is in Kuwait with 0.2/100,000. According to numbers that are not reliable enough in our country, it is at the level of 1.93/100,000. One of the striking issues in colon cancer is the differences in gender distribution and it is more common in men.
Colon cancer and risk factors
The risk of colon cancer increases after the age of 40. It reaches its highest level at the age of 50-55. Various studies indicate that colon cancers occur as a result of the mutual and complex relationships of hereditary susceptibility and environmental factors.
In recent years, we have gained a lot of information about the genetic factors that cause colon cancer. According to our new information, it is suggested that 5-10% of colon cancers are caused by hereditary factors.
It is determined that up to 20% of colon cancers are related to smoking. If this is certain, it is possible to hold smoking responsible for 16-20% of colon cancer deaths. A large study conducted in the USA However, no causal relationship has been found between smoking and colon cancer. According to this research, the risk of developing benign small polyps increases in those who have smoked for less than 20 years, the risk of developing benign large polyps in those who have smoked for more than 20 years, and the risk of developing cancer in those who have smoked for more than 35 years.
Can the risk of colon cancer be reduced?
There are some measures that reduce the risk of contracting the disease.
Research has shown that the risk of developing many cancers, including colon cancer, is reduced in individuals who exercise regularly. Exercises of moderate intensity or that cause the expenditure of 150 calories per day should be done 5 days a week for 30-60 minutes.
Excess weight increases the risk of cancer.
Not smoking. Like other cancers, smoking significantly increases the risk of colorectal cancer.
Studies have shown that excessive alcohol consumption increases the risk of colon cancer. Men should not consume more than two glasses of alcohol a day and women should not consume more than one glass a day.
Eating habits also play an important role in preventing colorectal cancer. Choosing high fiber, low fat foods is important as a precaution.
The above prevention methods alone do not completely prevent the development of colon cancer. Individuals at risk should definitely benefit from screening methods, even if they do not have any complaints.
Colonoscopy, which is the most effective screening method, means examining the layer covering the inner surface of the large intestine with the help of a thin, long, bendable camera, without the need for hospitalization. Removing the polyps detected during the examination is the most important practice for preventing cancer.
As a result, one should be alert in case of a change in defecation habits and blood in the stool. The most important thing is to perform screening tests and physical examinations of individuals in the high-risk class.
How does colon cancer start?
Almost all colon cancers are caused by a polyp. There is a consensus that it starts from the ground up. Polyp is the name given to a bulge and swelling that develops from the layer covering the inner surface of the intestine and grows into the intestine. Over time, form the polyp Cancer may occur on the basis of the polyp as a result of changes in the cells. Cancer cells, which are initially confined within the polyp, multiply over time and form a tumor mass, which invades the large intestine wall. Cancer cells that continue to grow uncontrolled can cause obstruction in the intestine after a certain period and spread to the surrounding and distant organs.
Polyps are one of the most common diseases of the large intestine. In a study conducted on healthy people, polyps were detected in 15-20% of the large intestines of adults. The probability of seeing polyps in the large intestine of an individual over the age of fifty increases even more and the rate reaches 40-50%. Polyps are observed mostly in the last parts of the large intestine, namely the sigmoid colon and rectum. This region is also the region where colon cancer is most common. On average, the time it takes for cancer to develop from a polyp is about 8-10 years.
Colon cancer symptoms
Colorectal cancer is easier and more effective if it is diagnosed in the early stages. It is treated successfully.
Possible symptoms are:
• blood or mucus in the stool,
• swelling in the stomach,
>• diarrhea or constipation lasting two weeks or more,
• feeling the need to go to the toilet even after emptying the bowels,
• pain or discomfort in the stomach area,
• weight loss and
• fatigue
These symptoms are usually associated with more common, smaller conditions (such as hemorrhoids, fissures), but this sometimes causes a delay in diagnosis and therefore treatment.
Colon cancer and diagnosis
Achieving a long life in colon cancer is possible with early diagnosis. Generally, when complaints reach a high level, the disease is advanced. Informing the public and screening are important for early diagnosis. Screenings are especially valuable in high-risk patients.
One of the earliest and easily recognized symptoms of colon cancer is the presence of blood in the stool. However, since these bleedings are generally attributed to hemorrhoid-like diseases among the public, they are ignored and the doctor is consulted late. Invisible amounts of bleeding, pressure It can be detected by laboratory methods.
Endoscopy and radiological imaging are the most important methods in the diagnosis and post-treatment follow-up of all digestive tract cancers. Some blood tests (tumor markers) may be valuable in the diagnosis of colon cancer and even in monitoring the disease after treatment.
Other clinical findings also have an important place in the diagnosis. These findings occur acutely and chronically. Acute clinical signs are caused by obstruction, perforation, or bleeding. Urgent intervention is required.
Changes in defecation habits are among the most common findings in colon cancer and chronic patients. Changes in the form of constipation or diarrhea are observed.
Another finding is that the stool is mucusy from time to time. Finally, another important finding is morning diarrhea. In addition to these important clinical symptoms, persistence of the feeling of defecation, abdominal pain and gas, and weight loss may be observed.
Colon cancer and its treatment
Among all digestive tract cancers, surgery is the most common. Colon cancers have the best treatment results. The average 5-year survival rate in patients who are in the operable stage and who have undergone surgery with modern examinations brought about in recent years is 40-50%, and this rate is over 85% in patients who can be treated in the early period. In other words, when detected on time, colon cancer can be definitively treated with surgery.
The principles of surgical treatment of colon and rectum cancer can be summarized as follows:
It is important to completely remove the part of the intestine containing the cancerous tissue. Since cancer generally tends to spread to the surrounding tissue, the surgeon removes a large area of normal surrounding tissue along with the cancer. If the intestine containing cancer has spread to a neighboring organ, the surgeon removes the neighboring organ as a whole, together with the intestine.
The tissue called mesentery, which connects the large intestine to the body, must also be removed. Within the mesenteric tissue, there are arteries (arteries) that provide blood circulation to the intestine and bring clean blood to it, and veins (veins) that collect dirty blood. In addition, lymph nodes, one of the defense organs of our body, are located in the mesentery, adjacent to the arteries. Removal of the mesentery during surgery It is necessary to remove the lymph nodes, which contain body defense cells and prevent cancer cells from spreading throughout the body.
It is also necessary to remove the lymph nodes. Lymph nodes normally filter body fluids like a filter, capture foreign substances, microbes and cancer cells in them, and cleanse our body from these harmful factors by destroying them. For this reason, it is necessary to remove the lymph nodes belonging to the large intestine section where the cancer is located during the surgery. This procedure is very important to prevent the spread of the disease.
As a result, a colon surgery performed for cancer is very different from those performed for other diseases. It is very important that the surgeon who will perform this surgery has knowledge and experience in cancer surgeries in terms of the treatment and subsequent course of the disease.
The second treatment method for colon cancer is chemotherapy. Drugs are used in this cancer before and after surgery or in widespread metastatic disease. In the last 10 years, new drugs have begun to extend the lifespan of patients, especially in metastatic disease.
Radiation also has a place in rectal cancer. Depending on the characteristics of the patient and the disease, radiotherapy is applied after or before surgery or without surgery. In recent years, radiotherapy has been combined with chemotherapy. If necessary, in inoperable rectal cancers, radiotherapy and/or chemotherapy may be used to regress the tumor and make it operable.
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