Colon Cancer (Colonic Carcinoma): Symptoms, Early Detection, and Treatment of Colon Cancer

Colon cancer is usually preceded by benign intestinal polyps, which, however, become malignant over the course of several years. Generally, this disease develops very slowly and often goes unnoticed because it has no symptoms. The first symptoms usually appear only in the late stages, often causing severe pain or bloody stools.

Colon cancer is the third most common cancer among men and the second most common among women in Germany. Every year, German hospitals record over 60,000 new cases. Approximately 29,000 of these cases involve women, and 34,000 involve men.

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The exact reason why a colon cell becomes a cancer cell is unclear. Damage occurs in specific genes within a cell. This “genetic damage” causes the cell to escape natural regulation and multiply uncontrollably.

Colon cancer can develop without any apparent cause. However, there are risk factors that can increase the likelihood of developing colorectal cancer. These include:

• Age: Colorectal cancer is more common in older patients. In most cases, these patients are over 50 years old
• Heredity: The presence of familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (HNPCC). These are very rare genetic disorders
• A history of ulcerative colitis or Crohn’s disease (an inflammatory disease of the colon) lasting more than 8–10 years
• Obesity
• Lifestyle: Lack of physical activity, excessive consumption of red meat, and excessive use of alcohol and nicotine

The risk of developing colorectal cancer appears to be reduced in:

• People who regularly eat fruits and vegetables.
• Patients who must take anti-inflammatory medications for other conditions (such as aspirin).

In most stages of the disease, those affected experience no symptoms or limitations. For this reason, colon cancer is often not detected until the late stages. By then, the chances of successful treatment are already declining. Many patients notice blood in their stool or stool that is becoming increasingly dark.

In addition, many patients complain of recurring intestinal cramps and severe pain that persists for increasingly longer periods. Just as with the pain and cramps, phases of diarrhea and constipation alternate. Frequent bowel movements are often accompanied by a strong, foul odor.

Loud bowel sounds and flatulence are also noticeable. These are associated with significant loss of blood, mucus, or stool. In addition to a progressive decline in physical performance, the disease is usually characterized by a persistent loss of appetite and fatigue. Once a noticeable pallor becomes apparent in those affected, unexplained weight loss usually follows. In addition, the lymph nodes enlarge and clearly palpable hardenings form in the abdominal cavity.

However, none of the symptoms described above are definitive indicators of colon cancer. In most cases, such symptoms can also occur in harmless situations. For example, they may be a sign of increased stress (irritable bowel syndrome). Nevertheless, a doctor should be consulted as soon as possible.

Doctors have various methods at their disposal for making a diagnosis. First, during an in-depth consultation, the doctor will ask for several key pieces of information to assess the risk of colon cancer. In addition to dietary habits, the doctor will therefore also inquire about the medical history of all close family members. A previous case of colon cancer among relatives generally warrants increased caution.

This is always followed by a physical examination. During this examination, the doctor thoroughly palpates the patient’s entire abdomen to check for any hard lumps. Finally, a blood sample is taken and analyzed. Diligent physicians also perform a painless digital rectal exam, as many colorectal tumors are located there.

Colon cancer can best be definitively diagnosed or ruled out with a colonoscopy. During this procedure, the doctor examines the entire colon for malignant growths. A colonoscopy can also be used to remove benign polyps that may develop into malignant tumor tissue. Therefore, a screening colonoscopy is recommended starting at age 50 for men and age 55 for women.

During a colonoscopy, the doctor performing the procedure inserts a long, flexible tube into the patient’s anus. A special gel is usually used to improve lubrication. At the end of the tube is a small camera that transmits video footage to a connected monitor.

The tube has a working channel through which small instruments, such as forceps or snares, can be inserted. The doctor uses these instruments to remove suspicious tissue for analysis after the examination. They are also used to remove any small polyps. This procedure does not require an inpatient stay.

A colonoscopy can be performed with or without sedation (artificial sleep).
In some cases, an examination may alternatively be performed using what is known as a colon capsule endoscopy. During this procedure, the patient swallows a small camera that records the entire colon on a video device. However, this procedure does not allow for the removal of a tissue sample or the excision of a polyp.

During a colonoscopy, colon polyps can be detected and easily removed | License: CC BY 3.0

A biopsy is the removal of a small piece of tissue from the body. This sample can then be examined under a microscope. During a colonoscopy, the doctor can perform a biopsy. This is done by inserting a thin grasping instrument through a lateral working channel on the colonoscope.

Once a diagnosis of colon cancer has been confirmed, further tests must be performed to determine the extent of the tumor. These include, for example,

• a computed tomography (CT) scan,
• magnetic resonance imaging,
• an ultrasound examination, and
• other tests.

These tests are referred to as “staging” (determining the tumor stage) of the cancer. The goal of staging tests is to determine:

• How large the tumor is in the colon and whether it has partially or completely penetrated the colon wall.
• Whether the colon cancer has spread to the local lymph nodes.
• Whether the colon cancer has already spread to other parts of the body (metastasized).

Determining the exact stage of the cancer is necessary to provide the best possible treatment options. Furthermore, this provides a reasonable indication of the chances of recovery (prognosis).

Treatment of the disease depends primarily on the aggressiveness of the tumor and its spread to surrounding tissue. In addition, the patient’s overall health plays a major role. In particular, if the cancer has already spread to the lymph nodes and formed secondary tumors (metastases), a combination of several treatment approaches is unavoidable.

In the early stages, the disease can usually be completely cured with surgery. In the late stages, adjuvant chemotherapy is often used. In some cases, comprehensive radiation therapy is even performed. In addition, there are numerous other treatment options in which medications specifically target the cancer cells.

Surgery plays a particularly important role in the treatment of colon cancer. The goal of the procedure is to remove all tumor tissue, including all associated lymph nodes and lymphatic vessels. In addition, the surgeon thoroughly examines the abdominal cavity to locate any secondary tumors that may have formed. Colon cancer can spread to the liver and lungs. In such cases, it is advisable to also remove large portions of both organs and their supplying blood vessels.

With colon cancer, it is often necessary to remove a large portion of the large intestine. In this case, the two separated ends are carefully sutured together. The extent of the surgery depends on numerous factors. These include not only the location and size of the tumor but, above all, its blood supply and how far it has spread throughout the body. If other organs, such as the spleen or kidneys, have been affected, it may be necessary to remove them completely.

If all of the tumor tissue is completely removed during surgery, the disease is considered cured. In this case, it has no chance of spreading throughout the body again. It may be necessary to temporarily create a colostomy. This allows the section of the intestine that was operated on to heal much more quickly.

During surgery, the goal is to remove all of the tumor tissue.

One or both of these options may be necessary as part of treatment. This depends on the location and stage of the colorectal carcinoma. Chemotherapy is a drug treatment that targets cancer cells.

Radiation therapy is a treatment that focuses high-energy radiation on cancerous tissue. This kills cancer cells or prevents them from multiplying. This therapy is most commonly used when the tumor is located in the rectum.

If the tumor in the rectum has reached a certain depth of invasion, so-called neoadjuvant radiation therapy and/or chemotherapy is performed before surgery. The goal is to shrink the tumor before surgical removal. This increases the chances of a successful surgical procedure.

When chemotherapy or radiation therapy is used after surgery, this form is called adjuvant chemotherapy or adjuvant radiation therapy. The goal of this treatment is to kill every single cancer cell that has broken away from the primary tumor and could not be removed during surgery.

Without treatment, colorectal cancer will grow, become larger, and spread to other parts of the body (“metastasize”). In many cases, a tumor grows slowly. It can remain inside the intestine for several months before breaking through the intestinal wall and/or spreading. The chances of a cure are very good with early treatment.

If the colorectal carcinoma has broken through the intestinal wall or has metastasized, the chance of a cure is significantly lower. Nevertheless, treatment can often slow the progression of the cancer.

Colon cancer can be effectively prevented. This involves specifically minimizing all risk factors and placing great emphasis on early detection. Numerous diseases and lifestyle factors can drastically increase the risk of developing colon cancer. For example, ulcerative colitis and Crohn’s disease are known to be precursors to colon cancer. In addition to genetic factors, diet also has a major influence on an individual’s risk.

A balanced diet rich in fiber and low in red meat reduces the risk of developing the disease. Furthermore, regular physical activity and reducing fat intake are also important. Finally, chronic obesity and tobacco use also increase the likelihood of developing cancer.

A screening colonoscopy should always be considered if there are persistent changes in bowel habits or blood in the stool. A doctor should be consulted at the latest when there is a noticeable decline in energy levels and pallor combined with unexplained weight loss. This approach effectively prevents the risks associated with the disease and the serious consequences of delayed treatment.

Since the risk of developing colorectal cancer increases with age, a colonoscopy should be performed in men starting at age 50 and in women starting at age 55. This applies regardless of whether bowel symptoms are present or not. If there is a family history of colorectal cancer, it is advisable to have the colon examined even earlier.

What symptoms can occur with colon cancer?

Possible symptoms of colon cancer include blood in the stool, constipation, persistent changes in bowel habits, abdominal pain, and weight loss. Since symptoms often do not appear until the disease has reached an advanced stage, colon cancer frequently goes unnoticed for a long time. Other possible symptoms of colon cancer include fatigue and a decrease in energy levels. In some patients, the disease is first detected during a screening exam.

How does colorectal cancer develop?

Colon cancer usually develops from benign colon polyps, which can progress into malignant tumors over time. The development of colon cancer is influenced by genetic factors, familial adenomatous polyposis, ulcerative colitis, or Crohn’s disease. Other causes and risk factors include age, diet, and lifestyle. The risk of colon cancer increases significantly, particularly after age 50.

How is colon cancer diagnosed?

Colon cancer is typically diagnosed through a colonoscopy. During the procedure, the doctor can identify suspicious tissue and take a tissue sample. Imaging techniques are also used to assess the tumor’s location, possible metastases in the liver or lungs, and affected lymph nodes. An accurate diagnosis is crucial for determining the course of treatment for colon cancer.

How is colon cancer treated?

Treatment for colorectal cancer depends on the stage of the disease. In many cases, the tumor is completely removed through surgery. Depending on the tumor’s location, efforts may be made to preserve the natural anal opening. For Stage III or advanced cases, adjuvant chemotherapy is often recommended. If a cure is no longer possible, treatment can prolong life and alleviate symptoms.

How important are early detection and follow-up care?

Early detection plays a crucial role in colorectal cancer, as the disease usually has a very good chance of being cured in its early stages. A fecal occult blood test and a colonoscopy help detect precancerous lesions early on. Regular follow-up care is necessary after surgery or chemotherapy. It serves to detect metastases, secondary tumors, or a suspected recurrence in a timely manner.