Understanding Colon Cancer -- Diagnosis and Treatment

How Is Colorectal Cancer Diagnosed?

The current American Cancer Society screening guidelines for colorectal cancer n an average risk patient begin at the age of 45 and include the following options:

Stool based tests:

  1. Fecal immunochemical test (FIT) yearly
  2. Guaiac fecal occult blood test yearly
  3. Stool DNA test every 3 years

Structural examinations:

  1. Colonoscopy every 10 years
  2. Flexible sigmoidoscopy every 5 years
  3. CT colonography (virtual colonoscopy) every 5 years.

If you have a positive result on a screening test that is not a colonoscopy, further evaluation should be performed on a timely basis with a colonoscopy test to take a look at your entire colon.

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, chemotherapy, targeted therapy, and immunotherapy. 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.

Targeted therapy drugs for treating colon cancer work in an entirely different way. These drugs work by blocking the cancer’s blood supply or blocking a protein or genetic change made by the cancer to enhance it growth. They can be used to treat advanced colorectal cancer that has spread (metastasized) to other parts of the body. These drugs include: bevacizumab (Avastin), cetuximab (Erbitux), panitumumab (Vectibix), regorafenib (Stivarga),and ziv-aflibercept (Zaltrap) .


Immunotherapy involves drugs that stimulate the body’s own immune system to recognize and destroy cancer cells. Pembrolizumab (Keytruda) and Nivolumab (Opdivo) are called immune checkpoint inhibitors and are sometimes used to treat advanced colorectal cancer.

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 09, 2018



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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