โรคมะเร็งลำไส้ใหญ่ - Colon Cancer สาเหตุ อาการ การวินิจฉัยและการรักษา

Colon Cancer

Colon cancer can happen at all age groups, but it is more common with senior adults. Colon cancer usually starts as polyps, as time progresses, these polyps turn into colon cancers.

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Colon Cancer

Colon cancer is cancer that starts in the large intestine (known as the colon) and is located in the last part of the digestive tract. It is sometimes known as colorectal cancer which refers to the combination of colon cancer and rectal cancer. Colon cancer can happen in all age groups, but it is more common in senior adults. Colon cancer usually starts as polyps, a type of noncancerous benign cell clumps that form inside the colon. As time progresses, these polyps turn into colon cancers. There are many available treatments to help manage colon cancer whether it's surgery, radiation therapy, or drug treatments like chemotherapy, targeted therapy, and immunotherapy.

Signs and symptoms of colon cancer

  • Continuous changes to your bowel habits as experiencing diarrhea, constipation, or a change to the stool frequency
  • Bleeding from the rectum or bloody stool
  • Recurrent abdominal discomfort and pain including stomach cramps or gas
  • The feeling of incomplete bowel movement or when you feel that your bowel doesn't empty fully
  • Feeling weak or suffering fatigue
  • Unexplained loss of weights

However, the majority of people with early stages of colon cancer tend to have no visible symptoms.

When to see a doctor

You should seek a medical professional if you notice any ongoing symptoms that are concerning you. It is generally recommended that people at the age of 50 should start screenings for colon cancer.

Causes of colon cancer

Colon cancer generally starts when healthy cells begin to mutate in the DNA within the colon. The role of the DNA within a cell is to instruct cells on what needs to be done. In general, healthy cells will grow and divide systematically for your body to function. However, when the cell mutates and turns cancerous, it goes out of control and begins dividing into more new cells than needed. A tumor is formed, as cells start to accumulate. As time progresses, cancer cells start to multiply and begin invading and destroying normal tissue located nearby. Those cancer cells break away from the tumor and form in other parts of the body.

However, doctors still aren't certain about the actual causes of most colon cancers.

Risk factors

These are risk factors that could increase the risk for the development of colon cancer.

  • Senior adults are more likely to have colon cancer. Even though colon cancer can occur at any age, the majority of people with colon cancer are older than 50. At present, there has been an increase in the number of people below 50 years of age with colon cancer.
  • African-American race tends to have a greater risk of developing colon cancer than those of other races.
  • Patients with a history of colorectal cancer or noncancerous polyps will have a higher risk of colon cancer in the future.
  • Inflammatory intestinal conditions include chronic inflammatory diseases in the colon. Those with ulcerative colitis and Crohn's disease will have more risk of developing colon cancer.
  • Those that inherit gene mutations through family generations will have a significant risk of developing colon cancer. However, generally, only a small percentage of colon cancer patients are found to be linked to inherited genes. Familial adenomatous polyposis (FAP) and Lynch syndrome are the two most common inherited syndromes that can increase the risk of colon cancer. These types of syndromes are also known as hereditary nonpolyposis colorectal cancer (HNPCC).
  • Those with a history of colon cancer in the family will be more likely to develop this type of cancer.
  • There is an association between diets that are low-fiber or high-fat and colon cancer and rectal cancer.
  • People who have a sedentary lifestyle are more likely to develop colon cancer.
  • Diabetics or those with insulin resistance conditions tend to have an increased risk of colon cancer.
  • Obesity leads to an increased risk of colon cancer. An obese patient will also have an increased chance of dying from colon cancer than those with normal weight.
  • Smokers may have a higher risk of colon cancer.
  • Heavy alcohol consumption increases colon cancer risk.
  • Patients who previously received radiation therapy for cancer in the area around the abdomen have an increased risk of colon cancer.

Diagnosis

Doctors will most likely recommend people with an average risk of colon cancer to begin screening for colon cancer around the age of 50. Those with an increased risk of colon cancer, on the other hand, should consider screening for colon cancer at a sooner rate.

There are several screening options. Each option has both advantages and disadvantages. Colonoscopy, for example, can be used for screening, but it can also remove polyps during the procedure before they turn into cancerous cells.

Diagnosing processes for colon cancer

Your doctor may recommend these tests or procedures if you have the signs and symptoms indicating the possibility of developing colon cancer.

  • Colonoscopy is when your doctor uses a long tube-like scope, attached to a tiny video camera to monitor and view the inside of your entire colon and rectum. The doctor will pass surgical tools through the long tube and pinch out tissue samples if he or she finds any suspicious areas. The collected biopsies will be taken for further analysis. The next process will be to remove polyps.
  • Blood tests will be taken to find a chemical called carcinoembryonic antigen (CEA). Colon cancers sometimes produce CEA. Over time, the CEA level in the blood might help your doctor to forecast the prognosis and if the disease is responding to the treatment.

Different stages of colon cancer

Your doctor may recommend you take staging tests after you’ve been diagnosed with colon cancer. These tests will help your doctor determine the right treatment for you. Imaging procedures such as CT scans in the area of the abdomen, pelvis, and chest may be included in the staging test. However, in most cases, cancer stages may not be fully determined until after the patient undergoes surgery for colon cancer. Roman numerals are used to determine the stages of colon cancer. For the colon cancer stages, the Roman number system starts from 0 to IV, 0 indicates the lowest stage of cancer. This type of cancer is still limited in number and remains inside the colon. The IV refers to the most advanced stage of cancer. It is when the cancerous cells have expanded to other parts of the body.

Treatment options for colon cancer

The appropriate treatments to treat colon cancer will depend on your situation such as the area where the cancer is located on your body, the stage of cancer, or if there are any other health conditions. Surgery is a treatment that is generally used to treat colon cancer. Sometimes the doctor may also recommend other treatments including radiation therapy and chemotherapy.

For early-stage colon cancer, the doctor may recommend minimally invasive procedures which are surgical techniques for the treatment of colon cancer.

  • Polypectomy or the removal of polyps during colonoscopy will be recommended by your doctor if the cancer is small and remains limited and contained within the polyp. Your doctor may still be able to remove it completely in the early stage of colon cancer.
  • Endoscopic mucosal resection is when your surgeon removes polyps that are larger during the colonoscopy procedure. The surgeon will use a specialized tool to remove the polyp as well as a small amount of the inner lining of the colon.
  • Laparoscopic surgery is a minimally invasive surgical technique to remove polyps that can't be removed during a colonoscopy. Your surgeon will perform several small incision operations of the abdominal wall. Cameras will be attached to instruments that will be inserted into the wall of your abdomen. The images from the camera will display the inside of your colon through a video monitor. The surgeon may take samples from the lymph nodes from the area of cancer.

Other surgical procedures may be recommended by your surgeon if cancer has grown throughout your colon.

  • A partial colectomy is a minimally invasive procedure when the surgeon removes the cancerous part of your colon as well as a small part of the normal tissue located on either side of the cancer areas. Most of the time, the surgeon will be able to reconnect the healthy area inside your colon or rectum.
  • Ostomy or surgery to create a way for waste to leave your body. An ostomy is often done when the reconnecting procedure of the healthy area within the colon or rectum becomes impossible. The procedure requires the surgeon to construct an opening to the wall inside of the abdomen to eliminate stool into a bag that is placed upon the opening wall. Most of the time, ostomy surgery is temporary. It will give time for your colon and rectum to be able to heal after the surgery. In other cases, the colostomy might be a permanent surgery.
  • Lymph node removal is when the surgeon removes the nearby lymph nodes during colon cancer surgery and takes them to be tested for cancer.

Your surgeon may recommend you undergo an operation to help relieve the pressure of blockage inside your colon if you are in the advanced stages of cancer. The surgery will also be recommended if your overall health conditions are poor as this type of treatment will be done to help relieve the symptoms you may experience from colon cancer. These symptoms may include blockage, bleeding, or pain.

In some cases, the cancer has spread to the liver or the lung, but your health conditions remain good, you may be recommended to undergo localized treatments like surgery to remove the cancer. Your doctor may advise you to use chemotherapy before or after the surgery. This treatment will help provide patients with more chances of longer cancer-free lives.

What is chemotherapy treatment?

Chemotherapy is the use of drugs to destroy cancerous cells. For colon cancer, chemotherapy will be given after the surgery procedures, if cancer cells become larger. Chemotherapy is also used for cancer cells that have spread to the lymph nodes. Chemotherapy can be used to destroy any cancer cells that are remaining in the body. It will also help to reduce cancer recurrence risk. Sometimes, chemotherapy will be used before the operation takes place as it will help to shrink the size of large cancer cells, making it easier for the removal procedure.

Sometimes it's combined with radiation therapy. The treatment can also be used to help relieve other colon cancer symptoms that can’t be removed with the surgery procedures. In case the cancer cells have spread to other parts of the body, the doctor may also recommend the use of chemotherapy. Sometimes the treatment of colon cancer consists of a combination of chemotherapy and radiation therapy.

Radiation therapy treatment

The radiation therapy treatment uses powerful energy beams including X-rays or protons to destroy cancerous cells. Radiation therapy sometimes will be used before the operation takes place as it will help to shrink the size of large cancer cells, making it easier for the removal procedure. Radiation therapy might be a recommended option to help relieve symptoms of pain when the surgery is not optional. Sometimes the treatment of colon cancer consists of a combination of radiation therapy and chemotherapy.

What is targeted drug therapy?

Targeted-drug therapy is a treatment that focuses on specific abnormal areas within the cancerous cells. The targeted drug treatments work by blocking abnormal cells and destroying the cancer cells. Sometimes, targeted-drug treatments are used in combination with chemotherapy. This type of treatment is often used to treat those with advanced colon cancer.

What is immunotherapy?

Immunotherapy is a type of treatment that helps your immune system to be able to attack cancer cells. The ability of your immune system to fight cancer cells may weaken as cancer cells will produce proteins that will blind the cells in the immune system from detecting the cancerous cells. The treatment of immunotherapy will interfere with the process of protein production.

Immunotherapy is typically reserved for those with advanced colon cancer. You may be instructed to test your cancer cells to see if you will be able to respond to the immunotherapy.

Palliative care

Palliative care is a specialized medical care program that helps support patients by relieving the pain and other symptoms of any serious illness. A team of doctors, nurses, and other trained professionals will support the patient by working with their families and other doctors to provide extra support that will assist with the current treatment program.

Published: 13 Sep 2020

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