Understanding Colon Cancer -- Diagnosis and Treatment

How Is Colorectal Cancer Diagnosed?

Beginning at the age of 50, everyone should be screened regularly for colorectal cancer (earlier screening is recommended for some high-risk groups). There are several options.

The traditional screening routine was for the doctor to perform a digital rectal exam once a year and for you to collect three stool samples to be tested for traces of blood. Also, every three to five years you would receive a sigmoidoscopy and a double-contrast barium enema to look at the lower part of the bowel. If anything were abnormal then you would be referred for a colonoscopy. The colonoscopy is a complete evaluation of the colon and rectum with a scope or long, flexible tube similar to the sigmoidoscope but longer.

Biopsies or tissue samples of any suspicious-looking areas can be obtained during a colonoscopy for laboratory analysis.

Now, most doctors advocate going right to colonoscopy at age of 50. However, other studies are sometimes recommended when a patient is unable or unwilling to undergo colonoscopy.

A noninvasive screening procedure called virtual colonoscopy is available. It does away with the tube and instead uses spiral computed tomography, which produces a three-dimensional image of the colon after it has been emptied and partially inflated with air.

The current American Cancer screening guidelines for colon cancer in an average risk patient begin at the age of 50 and include the following options:

  • Flexible sigmoidoscopy every 5 years, or
  • Colonoscopy every 10 years, or
  • Double-contrast barium enema every 5 years, or
  • CT colonography (virtual colonoscopy) every 5 years.

Alternative screen options include a fecal immunochemical test (FIT) or guaiac-based fecal occult blood test every year, or a stool DNA test every 3 years. However, if you are at high risk of colon cancer due to a family history of colon cancer or polyps, screening intervals should begin earlier and be more frequent.

Any suspicious symptoms or abnormalities will alert your doctor to perform a colonoscopy to get a biopsy.

Should a biopsy confirm cancer, imaging tests using chest X-rays and CT scans of the abdomen, pelvis, and possibly chest are performed to find out whether the cancer has spread to other sites.

Blood tests will also be ordered to find out how well the liver and kidneys are functioning, to determine if you are anemic, and to measure the blood level of a substance called carcinoembryonic antigen (CEA), often found in higher-than-normal concentration in the presence of colorectal cancer, especially if it has spread.



What Are the Treatments for Colorectal Cancer?

Colorectal cancer treatment involves not only specific therapies for curing or controlling the disease, but also strategies for meeting a patient's emotional and physical needs. Restoring and maintaining quality of life is a central issue for doctors, as it should be for family members and friends as well. Many complementary cancer therapies can be valuable adjuncts when pursued along with standard medical treatment to help make the stresses of cancer and its treatment more tolerable. However, complementary therapies should never replace standard care.

The main types of treatment for colorectal cancer are surgery, radiation therapy, and chemotherapy. Depending on the stage of the cancer, these treatments may be combined.

Surgery is the most effective treatment for local colorectal tumors. Very small tumors can be removed through a colonoscope, but even with small tumors, removing the portion of the colon containing the tumor, the surrounding fat, and nearby lymph nodes is often the best treatment. Surgery may be performed either laparoscopically or by the open method, which uses larger incisions.

Usually, the surgeon can reconnect the healthy sections of the colon and rectum. When this is not possible, the surgeon forms an opening -- known as a stoma -- in the abdomen and reroutes the severed colon to it. Waste is collected in a bag worn over the stoma. This procedure, known as a colostomy, often is only temporary. Once the bowel has had time to heal, a second operation reconnects the colon and rectum. The need for permanent colostomy is more common with rectal cancer, since retaining the rectum may be difficult.

In the immediate period after surgery, the patient can expect to receive painkillers and other medication to ease temporary diarrhea or constipation. After surgery, patients are encouraged to eat nutritious foods, rich in calories and proteins, in order to gain strength and heal properly.

Radiation therapy is treatment with high-energy rays that destroy the cancer cells. For rectal cancer, radiation is usually given after surgery, along with chemotherapy (known as adjuvant therapy), in order to destroy any cancer cells left behind. In addition, it can be used along with chemotherapy before surgery (known as neoadjuvant therapy) in order to shrink a large tumor, making the surgery easier. In advanced rectal cancer, radiation can be used to shrink tumors that cause symptoms of bowel obstruction, bleeding, or pain.


Radiation therapy can be used in people with colon cancer when the tumor has attached to another organ in the abdomen, or if a tumor is found near the margins of the cancer that was removed.

Chemotherapy drugs are used to treat various stages of colorectal cancer. They include 5-flurouracil, capecitabine (Xeloda), irinotecan (Camptosar), oxaliplatin (Eloxatin), and the combination drug trifluridine and tipiracil (Lonsurf). Chemotherapy can also be administered directly into the liver if the colon cancer has metastasized there.

The FDA has approved five drugs for treating colon cancer that work an entirely different way. The drugs, bevacizumab (Avastin), cetuximab (Erbitux), panitumumab (Vectibix), regorafenib (Stivarga), and ziv-aflibercept (Zaltrap) are a form of cancer therapy called biologic therapy. These drugs work by blocking the cancer’s blood supply or blocking a protein made by the cancer to enhance its growth. They can be used to treat advanced colorectal cancer that has spread (metastasized) to other parts of the body.

Once cancer of either the colon or rectum is in remission, follow-up exams to check for recurrence are essential. But hundreds of thousands of people are living comfortable, normal lives even after colorectal surgery and a colostomy. Although adjusting to life after a colostomy requires time, support, and understanding, people with stomata have discovered for the most part they can eat, play, and work as well as they did before.

WebMD Medical Reference Reviewed by Laura J. Martin, MD on July 30, 2017



American Cancer Society. 

National Cancer Institute. 

WebMD Medical Reference from the American College of Physicians: “Section 12 V Colorectal Cancer.” 

FDA: "FDA approves new treatment for advanced colorectal cancer."

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