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Digestive Disorders > Lower Abdomen

Colon cancer

Dr. med. André Sommer

Dr. med. André Sommer

Colon cancer is one of the most common cancers in Germany. But through early detection and the therapies available today a large portion of colorectal cancer cases can be treated.

What types of colon cancer are there?

The intestine can be roughly divided into three sections:

  1. The small intestine connects directly to the stomach. It is the longest section of the intestine and is used primarily to absorb nutrients and vitamins from food.
  2. This is followed by the colon or large intestine which mainly serves to absorb water from the stool.
  3. The rectum is the last section of the intestine and passes into the anal canal. In this section, absorption of nutrients no longer occurs, it only serves as a reservoir for the stool before excretion. The sphincters at the end of the anal canal are crucial for continence.

Cancers of the colon and rectum are considered colorectal cancer. Colorectal cancer represents the second most common cancer in women and the third most common in men. In contrast, cancer of the small intestine is very rare.

About 95 percent of colon and rectal cancer cases arise from benign tumors. These benign tumors of the colon are called adenomas. If they malignant, they are called adenocarcinomas. In contrast to adenomas, adenocarcinomas have the possibility of forming metastases. This is why diagnostic measures for early detection are so important to detect the tumors before they become malignant.

What measures are available for the early detection of colorectal cancer?

Colonoscopy represents the most effective measure for the early detection of changes in the intestine. Colonoscopy is used as a standard procedure for early diagnosis from the age of 55 and the costs for the examination are borne by the health insurance companies. If the examination findings are normal, the examination is repeated every 10 years. Only about 10 percent of those affected fall ill before the age of 55, and more than half only after the age of 70.

If a colonoscopy is rejected, an annual test should be done for blood in the stool. With the FOBT (fecal occult blood test), also known as a hemoccult, traces of blood in the stool can be detected. However, this test is not very specific. A positive test neither proves the presence of colon cancer, nor does a negative test rule out a tumorous change in the intestinal tissue. Nevertheless, healthy intestinal mucosa is shown to bleed much less frequently, so that the detection of blood in the hemoccult test can at least indicate a pathological change in the intestinal mucosa.

What are the symptoms of colorectal cancer?

In most cases there are no noticeable early symptoms that would indicate colorectal cancer. There may be changes in bowel movements - both constipation as well diarrhea. If a tumor leads to a severe narrowing of the intestine, it can also lead to so-called "pencil stool". This means that the stool is pressed past the tumor and thereby pressed into a thin (“pencil-like”) structure. It can also lead to unwanted stool loss when passing gas. Blood in the stool can not only be an indication of hemorrhoids, but also of a tumor.

Other symptoms that can occur in the course of many tumor diseases and thus also in colon cancer are performance loss, weight loss, night sweats and fever. However, the cancer may not cause symptoms for a long time. That is why a colonoscopy is so important for early diagnosis.

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What options for therapy are available?

The three basic options available are surgery, radiotherapy as well as chemotherapy. The therapy depends on the exact location of the tumor and the stage at which it is diagnosed.

The stage classification depends on the size of the tumor and its depth of penetration into the intestinal tissue. Lymph node involvement and distant metastasis are also included, i.e. whether colon cancer has already spread to other organs.

Colon cancer surgery

The following applies to colorectal cancer in the colon: If there are no metastases or they are also operable, the surgical removal of the tumor is indicated. Depending on the area of the large intestine where the tumor is located, the left or right half of the large intestine is usually removed (hemicolectomy) or the entire colon may also be removed. Since the vital absorption of nutrients from food already takes place in the small intestine, life without a large intestine is quite possible.

Colon cancer chemotherapy

For both diagnostic and possibly therapeutic purposes, the lymph nodes in the area of the tumor are removed and examined pathologically in order to determine whether tumor cells have infiltrated into the lymph channels. If so, the chemotherapy is indicated. Chemotherapy can also be considered if the tumor is locally advanced and has not yet affected the lymph nodes. Various classic therapy schemes can be used for chemotherapy. In addition, the chemotherapy drugs can also be supplemented with antibody therapy. Studies have shown that this combination increases therapy success.

Radiation against colon cancer

Irradiation does not take place in the area of the large intestine. However, this method is used for the therapy of the rectum because it is easily accessible to radiation and is of great importance for therapy. From an advanced tumor growth, radiation is usually used in combination with chemotherapy (as chemoradiation) before surgery. As a result, the local recurrence rate could be reduced by up to 50%. Nevertheless, the quality of the surgical removal of the tumor has a decisive influence on the prognosis. The aim is to operate in way that is continence preserving. If the location of the tumor is unfavorable, this may not be possible and an artificial intestinal exit may be necessary. Often, an artificial intestinal exit is also temporarily created, which, however, can be relocated after the end of therapy. After the operation, chemoradiation is also carried out again.

What is the prognosis for colorectal cancer?

There is no general prognosis. The key factor is whether the tumor is still local or has already spread. If neither lymphatic nor distant metastases are present, a 5-year survival rate of 90 percent can be assumed. The more the tumor has spread, the worse the prognosis. That is why it is always necessary to search for possible distant metastases before starting therapy, for example in the liver.

What follow-up care is done after a colon cancer illness?

After the diagnosis of colorectal cancer, the Carcinoembryonic antigen (CEA) in the blood is determined. This is used as a progress marker, since an increase in CEA indicates a relapse after completion of the therapy. For this reason, this value is determined every six months in the first two years and up to the fifth year annually for locally advanced tumors and in the case of lymph node metastasis. A colonoscopy should also be done six to 12 months postoperatively and then every five years. With rectal cancer, a computed tomography is performed after three months, small colonoscopies (sigmoidoscopy) every six months for the first two years and an X-ray examination of the thorax every year for the first five years.

How can lifestyle reduce the risk of colon cancer?

The risk of developing colon cancer can be reduced by a healthy lifestyle. This includes a diet with at least 30 grams a day of dietary fiber and a diet that contains a lot of fruits and vegetables. Red meat should be avoided. Regular sporting activity contributes to risk reduction as well. Obesity is also unfavorable. Trunk-emphasized fat, especially belly fat, is particularly dangerous here. By contrast, normal weight, i.e. a BMI (body mass index) below 25, is a protective factor.

Alcohol and tobacco use also increase the risk of developing colon cancer. Studies have shown that a weekly alcohol intake of 100 grams of alcohol increases the risk of developing colorectal cancer by 15 percent. The type of alcohol (wine, beer, etc.) does not matter, but only the amount. However, the influence of caffeine consumption has not been established.

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Dr. med. André Sommer

Dr. med. André Sommer

I’m André, a medical doctor from Berlin. Together with a team of medical doctors, nutritionists and data scientists we empower people to understand digestive issues with our app Cara Care.

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