Colon Polyps and Cancer

Colon cancer is a disease in which malignant (cancer) cells form in the tissues of the colon.

The colon is part of the body’s digestive system. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of the esophagus, stomach, and the small and large intestines. The first 6 feet of the large intestine are called the large bowel or colon. The last 6 inches are the rectum and the anal canal. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).

Age and health history can affect the risk of developing colon cancer.

Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Risk factors include the following:

  • Age 50 or older.
  • A family history of cancer of the colon or rectum.
  • A personal history of cancer of the colon, rectum, ovary, endometrium, or breast.
  • A history of polyps (small pieces of bulging tissue) in the colon.
  • A history of ulcerative colitis (ulcers in the lining of the large intestine) or Crohn's disease.
  • Certain hereditary conditions, such as familial adenomatous polyposis and hereditary nonpolyposis colon cancer (HNPCC; Lynch Syndrome).

Possible signs of colon cancer include a change in bowel habits or blood in the stool.

These and other symptoms may be caused by colon cancer. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:
  • A change in bowel habits.
  • Blood (either bright red or very dark) in the stool.
  • Diarrhea, constipation, or feeling that the bowel does not empty completely.
  • Stools that are narrower than usual.
  • Frequent gas pains, bloating, fullness, or cramps.
  • Weight loss for no known reason.
  • Feeling very tired.
  • Vomiting.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) depends on the following:
  • The stage of the cancer (whether the cancer is in the inner lining of the colon only, involves the whole colon, or has spread to other places in the body).
  • Whether the cancer has blocked or created a hole in the colon.
  • The blood levels of carcinoembryonic antigen (CEA; a substance in the blood that may be increased when cancer is present) before treatment begins.
  • Whether the cancer has recurred.
  • The patient’s general health.

Treatment options depend on the following:

  • The stage of the cancer.
  • Whether the cancer has recurred.
  • The patient’s general health.

There are different types of treatment for patients with colon cancer

Different types of treatment are available for patients with colon cancer. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.

Three types of standard treatment are used:

Surgery

Surgery (removing the cancer in an operation) is the most common treatment for all stages of colon cancer. A doctor may remove the cancer using one of the following types of surgery:

  • Local excision: If the cancer is found at a very early stage, the doctor may remove it without cutting through the abdominal wall. Instead, the doctor may put a tube through the rectum into the colon and cut the cancer out. This is called a local excision. If the cancer is found in a polyp (a small bulging piece of tissue), the operation is called a polypectomy.
  • Resection: If the cancer is larger, the doctor will perform a partial colectomy (removing the cancer and a small amount of healthy tissue around it). The doctor may then perform an anastomosis (sewing the healthy parts of the colon together). The doctor will also usually remove lymph nodes near the colon and examine them under a microscope to see whether they contain cancer.
  • Resection and colostomy: If the doctor is not able to sew the 2 ends of the colon back together, a stoma (an opening) is made on the outside of the body for waste to pass through. This procedure is called a colostomy. A bag is placed around the stoma to collect the waste. Sometimes the colostomy is needed only until the lower colon has healed, and then it can be reversed. If the doctor needs to remove the entire lower colon, however, the colostomy may be permanent.
  • Radiofrequency ablation: The use of a special probe with tiny electrodes that kill cancer cells. Sometimes the probe is inserted directly through the skin and only local anesthesia is needed. In other cases, the probe is inserted through an incision in the abdomen. This is done in the hospital with general anesthesia.
  • Cryosurgery: A treatment that uses an instrument to freeze and destroy abnormal tissue, such as carcinoma in situ. This type of treatment is also called cryotherapy.

Even if the doctor removes all the cancer that can be seen at the time of the operation, some patients may be given chemotherapy or radiation therapy after surgery to kill any cancer cells that are left. Treatment given after the surgery, to lower the risk that the cancer will come back, is called adjuvant therapy.

Chemotherapy

Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the spinal column, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy).

Chemoembolization of the hepatic artery may be used to treat cancer that has spread to the liver. This involves blocking the hepatic artery (the main artery that supplies blood to the liver) and injecting anticancer drugs between the blockage and the liver. The liver’s arteries then deliver the drugs throughout the liver. Only a small amount of the drug reaches other parts of the body. The blockage may be temporary or permanent, depending on what is used to block the artery. The liver continues to receive some blood from the hepatic portal vein, which carries blood from the stomach and intestine.

The way the chemotherapy is given depends on the type and stage of the cancer being treated.

Radiation therapy

Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type and stage of the cancer being treated.

The importance of screening

Each year 130,000 Americans are diagnosed with colorectal cancer, the second most common form of cancer in the United States. Fortunately, with advances in early detection and treatment, colorectal cancer is one of the most curable forms of the disease. By using a variety of screening tests, it is possible to prevent, detect, and treat the disease long before symptoms appear.

Almost all colorectal cancers begin as polyps, benign (non-cancerous) growths in the tissues lining the colon and rectum. Cancer develops when these polyps grow and abnormal cells develop and start to invade surrounding tissue. Removal of polyps can prevent the development of colorectal cancer. Almost all precancerous polyps can be removed painlessly using a flexible lighted tube called a colonoscope. If not caught in the early stages, colorectal cancer can spread throughout the body. More advanced cancer requires more complicated surgical techniques.

Most early forms of colorectal cancer do not cause symptoms, which makes screening especially important. When symptoms do occur, the cancer might already be quite advanced. Symptoms include blood on or mixed in with the stool, a change in normal bowel habits, narrowing of the stool, abdominal pain, weight loss, or constant tiredness.

Most cases of colorectal cancer are detected in one of four ways:

  • By screening people at average risk for colorectal cancer beginning at age 50
  • By screening people at higher risk for colorectal cancer (for example, those with a family history or a personal history of colon polyps or cancer)
  • By investigating the bowel in patients with symptoms
  • A chance finding at a routine check-up

Early detection is the best chance for a cure.

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