Colorectal Cancer - Symptoms, Cause and Treatment

Colorectal cancer is a type of cancer that grows in the large intestine (colon), or at the very bottom of the large intestine that is connected to the anus (rectum). This cancer can be called colon cancer or rectal cancer, depending on where cancer grows.

Most colorectal cancers start from colon polyps or tissue that grows on the inner wall of the colon or rectum. However, not all polyps will develop colorectal cancer. The likelihood of a polyp turning into cancer also depends on the type of polyp itself. There are 2 types of polyps in the large intestine, namely:

Adenoma polyp. This type of polyp can turn into cancer, so adenomas are also called precancerous conditions.

Hyperplastic polyps. This type of polyp is more common and does not usually become cancerous.

Apart from depending on the type of polyp, several factors can affect the change in polyps to colorectal cancer, such as the size of the polyps that are larger than 1 cm, there are more than 2 polyps in the colon or rectum, or if dysplasia (abnormal cells) is found after the polyp is removed.

Symptoms of Colorectal Cancer

Symptoms of colorectal cancer are often felt by patients when cancer has advanced far. The types of symptoms depend on the size and location of cancer. Some of the symptoms that can appear include:

• Diarrhea or constipation.
• Defecate that feels incomplete.
• Blood on the stool.
• Nausea.
• Gag.
• Stomach pain, cramps, or bloating.
• The body gets tired easily.
• Weight loss for no apparent reason.

Immediately consult a doctor if the symptoms above appear. In the early stages, the symptoms of colorectal cancer are often not felt. Therefore, regular checks should be done just in case.

Causes and Risk Factors for Colorectal Cancer

The abnormal growth of cells is the culprit behind all cancers, including colorectal cancer. However, it is not yet known exactly what causes these cells to develop uncontrollably.

Although the cause is unknown, several factors can trigger colorectal cancer, namely:

• Age. The risk of colorectal cancer increases with age. More than 90% of cases of colorectal cancer are experienced by someone aged 50 years or older.
• History of disease. A person with a history of cancer or colorectal polyps is more at risk of developing colorectal cancer. Likewise, someone from a family who has had cancer or colorectal polyps.
• Genetic disease. A person with an inherited disease, such as Lynch syndrome, is at increased risk of developing colorectal cancer.
• Inflammation of the intestine. Colorectal cancer has a high risk of attacking people with ulcerative colitis or Crohn's disease.
• Lifestyle. Lack of exercise, lack of fiber and fruit intake, consumption of alcoholic beverages, obesity or being overweight, and smoking increase the risk of colorectal cancer.
• Radiotherapy. Radiation exposure to the abdominal area increases the risk of colorectal cancer.
• Diabetes.

Colorectal Cancer Diagnosis

Colorectal cancer can be detected early through some screenings. Individuals over 50 years of age are advised to undergo routine screening as directed by a doctor. Each of these has its advantages and disadvantages. For this reason, it is important to consult a doctor before choosing the right screening for a patient.

A variety of screenings for colorectal cancer include:

Stool examination, including:

• Fecal occult blood test (FOBT) or occult blood test. This test aims to determine if there is any invisible blood in the stool through a microscope. FOBT is recommended to be done once a year. This test consists of 2 types, namely:

          Guaiac FOBT. The stool sample is placed on a special card, then given a chemical. The card will change color if the stool is positive for blood.

          Fecal immunochemical test (FIT). The stool sample is mixed with a special liquid, then it is put into a machine that contains antibodies to check for blood in the stool.

• FIT - DNA test, which is the FIT test combined with a test to detect DNA changes in feces. This examination is carried out every 1-3 years.

Sigmoidoscopy. This procedure inserts a thin tube equipped with a light and camera (sigmoidoscope) from the anus to the lower part of the colon to see if there are polyps or cancer. This tool is also equipped with instruments to remove polyps or take tissue samples to be examined under a microscope (biopsy). This test is done every 5-10 years, along with the FIT test every year.

Colonoscopy. This procedure is the same as a sigmoidoscopy but uses a longer tube to examine the inside of the rectum and the entire large intestine. If the test finds polyps or cancer, the doctor will remove the polyp or cancer. Colonoscopy is recommended to be done every 10 years.

CT colonography (virtual colonoscopy). This examination uses a CT scan machine to display an image of the colon as a whole, for later analysis. This test is done every 5 years.

After the patient is confirmed to have colorectal cancer, the doctor will run tests to determine the stage or stage of cancer development. The types of examinations that can be chosen include X-rays, CT scans, PET scans, or MRIs. Another examination procedure that can also be done to determine the stage of colorectal cancer is a lymph node biopsy, which is by taking a sample of the lymph nodes to be examined under a microscope.

In addition to examinations to determine the stage of cancer, there are other tests performed on people with colorectal cancer. One of them is measuring the level of CEA ( carcinoembryonic antigen ) in the blood. High CEA levels in the blood can be a sign that a person has colorectal cancer. A complete blood count, which is a count of the number of red blood cells, white blood cells, hemoglobin, and platelets, is also necessary to assess the patient's overall health.

Colorectal Cancer Stages

The development of colorectal cancer can be divided into several stages or stages, namely:

• Stage 0 - cancer appears in the innermost lining of the colon wall.
• Stage 1 - cancer has penetrated the second layer (mucosa) and has spread to the third layer (submucosa), but has not spread beyond the colon wall.
• Stage 2 - cancer has spread beyond the walls of the colon, and it is possible that it has spread to nearby organs, but has not spread to the lymph nodes.
• Stage 3 - cancer has spread beyond the walls of the colon and to one or more lymph nodes.
• Stage 4 - cancer has penetrated the colon wall and spread to organs far from the large intestine, such as the liver or lungs. Tumor size can vary.

Colorectal Cancer Treatment

Diagnosis and treatment of colorectal cancer as early as possible will increase the chances of recovery in sufferers. However, if cancer has developed at an advanced stage, treatment steps will be taken to prevent it from spreading as well as relieve the symptoms experienced by the patient.

As with other types of cancer, the treatment of colorectal cancer includes surgery, chemotherapy, and radiotherapy. The combination of the three treatment steps depends on the patient's health condition, as well as the extent of cancer spread.

Surgical procedure

Surgery is the main treatment for colorectal cancer. The doctor will perform a resection, which is to cut the part of the colon or rectum where cancer is growing. The tissue and lymph nodes around the affected area will also be removed. After that, the resection will be accompanied by anastomosis, which is the union of each end of the digestive tract that has been cut by stitching.

In cases of cancer where there is only a small amount of health remaining, anastomosis will be very difficult. This condition is usually treated with a colostomy, which is a hole (stoma) in the abdominal wall. The stoma is made connected to the end of the intestine, which has been cut, to pass stool through the abdominal wall. The excreted stool will be accommodated in a bag attached to the outside of the abdominal wall.

Colostomy can be temporary or permanent. A temporary colostomy is performed until the lower part of the colon has healed. Meanwhile, a permanent colostomy is performed on patients who have undergone complete removal of the rectum.

This therapy uses radio waves to heat and destroys cancer cells. Radiofrequency ablation can be performed by inserting electrodes into the skin, preceded by local anesthesia. It can also include inserting electrodes through an incision in the abdomen, preceded by general anesthesia in the hospital.

Cryosurgery

Cryosurgery is a procedure to freeze and destroy cancer cells using liquid nitrogen.

Chemotherapy and  radiotherapy

Chemotherapy and radiotherapy are therapies that aim to kill cancer cells and stop their multiplication. Chemotherapy can be given in the form of tablets (eg capecitabine ) or injectable forms ( 5-fluorouracil, irinotecan, oxaliplatin ). Meanwhile, radiotherapy is a therapy that uses high-power radiation. Radiotherapy can be given externally using a radiation beam, or internally by inserting a catheter or radiation-containing wire into the area of ​​the body that is affected by cancer.

Both are also used as therapy before or after surgery. When done before surgery, the goal is to shrink the tumor to make it easier to remove. While chemotherapy or radiotherapy after surgery aims to kill any remnants of cancer cells that have spread from the main location of cancer.

The following will describe the treatment of colorectal cancer, based on the stage experienced by the patient:

Stadium 0

Treatment of stage 0 colorectal cancer depends on the size of cancer. For small cancers, the oncology surgeon will perform excision surgery, which is surgery to remove the tumor and a small amount of surrounding tissue. Whereas in large cancers, the doctor will perform a colon resection, which is cutting the part of the colon and surrounding tissue affected by cancer. The lymph nodes around the colon will also be removed to be seen under a microscope, whether or not they have cancer. After the affected part is removed, the doctor will perform an anastomosis, which is the reconnection of the healthy part of the colon by stitching it.

Stadium 1

Similar to stage 0 colorectal cancer, the treatment of stage 1 colorectal cancer is colonic resection with anastomosis. For cancer located in the rectum, the doctor can run radiation therapy or chemotherapy after the resection is complete.

Stadium 2 dan Stadium 3

For cancer located in the colon, the doctor will perform a colon resection with anastomosis. Doctors can also provide chemotherapy drugs. Whereas for cancer located in the rectum, several treatment options can be done, namely by combining resection with chemotherapy and radiotherapy, along with active monitoring of the patient's condition.

Stadium 4

In stage 4 colon cancer, or cancer that comes back after treatment, some treatment options are as follows:

• Resection with or without anastomosis.
• Radiotherapy can be combined with chemotherapy to relieve symptoms experienced by patients.
• Chemotherapy to control tumor growth, with or without targeted therapy (angiogenesis inhibitors or monoclonal antibodies).
• In patients whose anus is partially obstructed by a tumor, the doctor will place a stent to help the rectum stay open.

For cases of colorectal cancer that has spread to the liver, lungs, or ovaries, the doctor may perform surgical removal procedures, depending on the patient's condition. For cases of cancer that has spread to the liver, surgery can be done in combination with chemotherapy before or after surgery.

Another treatment option is chemoembolization, which is the administration of chemotherapy directly through the arteries leading to the tumor to block the blood supply to tumor cells. Meanwhile, for colon cancer patients who cannot undergo surgery, the doctor will perform radiofrequency ablation or cryosurgery.