Colorectal Cancer Diagnosis
Colorectal Cancer: Diagnosis
The doctors use different tests to diagnose colon cancer.
They also do tests to learn if cancer has spread to another part of the body from where it started. If this happens, it is called metastasis. For example, imaging tests can show if cancer has spread. Imaging tests show pictures of the inside of the body. Doctors may also do tests to learn which treatments could work best.
For most types of cancer, a biopsy is the only sure way for the doctor to know whether an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.
This section describes options for diagnosing colorectal cancer. Not all tests listed below will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:
- The type of cancer suspected
- Your signs and symptoms
- Your age and general health
- Your medical and family history
- The results of earlier medical tests
In addition to a physical examination, the following tests may be used to diagnose colorectal cancer.
- Colonoscopy- allows the doctor to look inside the entire rectum and colon while a patient is sedated. A colonoscopist is a doctor who specializes in performing this test. If colorectal cancer is found, a complete diagnosis that accurately describes the location and spread of the cancer may not be possible until the tumor is surgically removed.
- Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis of colorectal cancer. A pathologist then analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease. A biopsy may be performed during a colonoscopy, or it may be done on any tissue that is removed during surgery. Sometimes, a CT scan or ultrasound (see below) is used to help perform a needle biopsy. A needle biopsy removes tissue through the skin with a needle that is guided into the tumor.
- Molecular testing of the tumor. Your doctor may recommend running laboratory tests on a tumor sample to identify specific genes, proteins, and other factors unique to the tumor. The results of these tests can help determine your treatment options.
All colorectal cancers should be tested for problems in mismatch repair proteins, called a mismatch repair defect (dMMR). There are 2 reasons for this testing. First, it is a way to look for Lynch syndrome. Second, the results will be used to find out if immunotherapy should be considered in patients with metastatic disease. This testing can either be done using special staining of the tissue taken from a biopsy or surgery or by doing analyses that look for changes called microsatellite instability (MSI).
If you have metastatic or recurrent colorectal cancer, a sample of tissue from the area where it spread or recurred is preferred for testing, if available.
- Blood tests. Because colorectal cancer often bleeds into the large intestine or rectum, people with the disease may become anemic. A test of the number of red cells in the blood, which is part of a complete blood count (CBC), can indicate that bleeding may be occurring.
Another blood test detects the levels of a protein called carcinoembryonic antigen (CEA). High levels of CEA may indicate that a cancer has spread to other parts of the body. CEA is not a perfect test for colorectal cancer because levels are high for only about 60% of people with colorectal cancer that has spread to other organs from the colon. In addition, other medical conditions can cause CEA to increase. A CEA test is most often used to monitor colorectal cancer for people who are already receiving treatment. It is not useful as a screening test.
- Computed tomography (CT or CAT) scan. A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. A CT scan can be used to measure the tumor’s size. Sometimes a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow. In a person with colorectal cancer, a CT scan can check for the spread of cancer to the lungs, liver, and other organs. It is often done before surgery.
- Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. MRI can be used to measure the tumor’s size. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow. MRI is the best imaging test to find where the colorectal cancer has grown.
- Ultrasound. An ultrasound uses sound waves to create a picture of the internal organs to find out if cancer has spread. Endorectal ultrasound is commonly used to find out how deeply rectal cancer has grown and can be used to help plan treatment. However, this test cannot accurately detect cancer that has spread to nearby lymph nodes or beyond the pelvis. Ultrasound can also be used to view the liver, although CT scans or MRIs (see above) are better for finding tumors in the liver.
- Chest x-ray. An x-ray is a way to create a picture of the structures inside of the body, using a small amount of radiation. An x-ray of the chest can help doctors find out if the cancer has spread to the lungs.
- Positron emission tomography (PET) or PET-CT scan. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into the patient’s body. This sugar substance is taken up by cells that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. A scanner then detects this substance to produce images of the inside of the body. PET scans are not regularly used for all people with colorectal cancer, but there are specific situations when your doctor may recommend one.
In cancer care, different types of doctors often work together to create a patient’s overall treatment plan that usually includes or combines different types of treatments. This is called a multidisciplinary team. For colorectal cancer, this generally includes a surgeon, medical oncologist, radiation oncologist, and a gastroenterologist. A gastroenterologist is a doctor who specializes in the function and disorders of the gastrointestinal tract. Cancer care teams include a variety of other health care professionals, such as physician assistants, nurse practitioners, oncology nurses, social workers, pharmacists, counselors, dietitians, and others.
Descriptions of the common types of treatments used for colorectal cancer are listed below, followed by a brief outline of treatment options listed by stage. Your care plan may also include treatment for symptoms and side effects, an important part of cancer care.
Treatment options and recommendations depend on several factors, including the type and stage of cancer, possible side effects, and the patient’s preferences and overall health. Take time to learn about all of your treatment options and be sure to ask questions about things that are unclear. Talk with your doctor about the goals of each treatment and what you can expect while receiving the treatment. These types of talks are called “shared decision making.” Shared decision making is when you and your doctors work together to choose treatments that fit the goals of your care. Shared decision making is particularly important for colorectal cancer because there are different treatment options.
In order to tailor the treatment to each patient, all treatment decisions should consider such factors as:
- The patient’s other medical conditions
- The patient’s overall health
- Potential side effects of the treatment plan
- Other medications that the patient already takes
- The patient’s nutritional status and social support
Below are explanations about each main type of colorectal cancer treatment.
Surgery is the removal of the tumor and some surrounding healthy tissue during an operation. It is often called surgical resection. This is the most common treatment for colorectal cancer. Part of the healthy colon or rectum and nearby lymph nodes will also be removed. While both general surgeons and specialists may perform colorectal surgery, many people talk with specialists who have additional training and experience in colorectal surgery. A surgical oncologist is a doctor who specializes in treating cancer using surgery. A colorectal surgeon is a doctor who has received additional training to treat diseases of the colon, rectum, and anus. Colorectal surgeons used to be called proctologists.
In addition to surgical resection, surgical options for colorectal cancer include:
- Laparoscopic surgery. Some patients may be able to have laparoscopic colorectal cancer surgery. With this technique, several viewing scopes are passed into the abdomen while a patient is under anesthesia. Anesthesia is a medicine that blocks the awareness of pain. The incisions are smaller and the recovery time is often shorter than with standard colon surgery. Laparoscopic surgery is as effective as conventional colon surgery in removing cancer. Surgeons who perform laparoscopic surgery have been specially trained in that technique.
- Colostomy for rectal cancer. Less often, a person with rectal cancer may need to have a colostomy. This is a surgical opening, or stoma, through which the colon is connected to the abdominal surface to provide a pathway for waste to exit the body. This waste is collected in a pouch worn by the patient. Sometimes, the colostomy is only temporary to allow the rectum to heal, but it may be permanent. With modern surgical techniques and the use of radiation therapy and chemotherapy before surgery when needed, most people who receive treatment for rectal cancer do not need a permanent colostomy. Learn more about colostomies.
- Radiofrequency ablation (RFA) or cryoablation. Some patients may have surgery on the liver or lungs to remove tumors that have spread to those organs. Other ways include using energy in the form of radiofrequency waves to heat the tumors, called RFA, or to freeze the tumor, called cryoablation. Not all liver or lung tumors can be treated with these approaches. RFA can be done through the skin or during surgery. While this can help avoid removing parts of the liver and lung tissue that might be removed in regular surgery, there is also a chance that parts of tumor will be left behind.
Side effects of surgery
Before surgery, talk with your health care team about the possible side effects from the specific surgery you will have and ask how side effects can be prevented or relieved. In general, the side effects of surgery include pain and tenderness in the area of the operation. The operation may also cause constipation or diarrhea, which usually goes away after a while. People who have a colostomy may have irritation around the stoma. If you need to have a colostomy, the doctor, nurse, or an enterostomal therapist, who is a specialist in colostomy management, can teach you how to clean the area and prevent infection.
Many people need to retrain their bowel after surgery. This may take some time and assistance. You should talk with your doctor if you do not regain good control of bowel function.
Radiation therapy is the use of high-energy x-rays to destroy cancer cells. It is commonly used for treating rectal cancer because this tumor tends to recur near where it originally started. A doctor who specializes in giving radiation therapy to treat cancer is called a radiation oncologist. A radiation therapy regimen, or schedule, usually consists of a specific number of treatments given over a set period of time.
External-beam radiation therapy. External-beam radiation therapy uses a machine to deliver x-rays to where the cancer is located. Radiation treatment is usually given 5 days a week for several weeks. It may be given in the doctor's office or at the hospital.
Stereotactic radiation therapy. Stereotactic radiation therapy is a type of external-bean radiation therapy that may be used if a tumor has spread to the liver or lungs. This type of radiation therapy delivers a large, precise radiation dose to a small area. This technique can help save parts of the liver and lung tissue that might otherwise have to be removed during surgery. However, not all cancers that have spread to the liver or lungs can be treated in this way.
Other types of radiation therapy. For some people, specialized radiation therapy techniques, such as intraoperative radiation therapy or brachytherapy, may help get rid of small areas of cancer that can not be removed with surgery.
- Intraoperative radiation therapy. Intraoperative radiation therapy uses a single, high dose of radiation therapy given during surgery.
- Brachytherapy. Brachytherapy is the use of radioactive "seeds" placed inside the body. In 1 type of brachytherapy with a product called SIR-Spheres, tiny amounts of a radioactive substance called yttrium-90 are injected into the liver to treat colorectal cancer that has spread to the liver when surgery is not an option. Limited information is available about how effective this approach is, but some studies suggest that it may help slow the growth of cancer cells.
Radiation therapy for rectal cancer. For rectal cancer, radiation therapy may be used before surgery, called neoadjuvant therapy, to shrink the tumor so that it is easier to remove. It may also be used after surgery to destroy any remaining cancer cells. Both approaches have worked to treat this disease. Chemotherapy is often given at the same time as radiation therapy, called chemoradiation therapy, to increase the effectiveness of the radiation therapy.
Chemoradiation therapy is often used in rectal cancer before surgery to avoid colostomy or reduce the chance that the cancer will recur. One study found that chemoradiation therapy before surgery worked better and caused fewer side effects than the same radiation therapy and chemotherapy given after surgery. The main benefits included a lower rate of the cancer coming back in the area where it started, fewer patients who needed permanent colostomies, and fewer problems with scarring of the bowel where the radiation therapy was given.
Radiation therapy is typically given in the United States for rectal cancer over 5.5 weeks before surgery. However, for certain patients (and in certain countries), a shorter course of 5 days of radiation therapy before surgery is appropriate and/or preferred.
A newer approach to rectal cancer is currently being used for certain people. It is called total neoadjuvant therapy (or TNT). With TNT, both chemotherapy and chemoradiation therapy are given for about 6 months before surgery. This approach is still being studied to determine which patients will benefit the most.
Side effects of radiation therapy
Talk with your doctor about the possible side effects of your radiation therapy regimen. Side effects from radiation therapy may include fatigue, mild skin reactions, upset stomach, and loose bowel movements. It may also cause bloody stools from bleeding through the rectum or blockage of the bowel. Most side effects go away soon after treatment is finished.
Sexual problems, as well as infertility (the inability to have a child) in both men and women, may occur after radiation therapy to the pelvis. Before treatment begins, talk with your doctor about the chances that the treatment will affect sexual health and fertility and the available options for preserving fertility.
Therapies using medication
Systemic therapy is the use of medication to destroy cancer cells. This type of medication is given through the bloodstream to reach cancer cells throughout the body. Systemic therapies are generally prescribed by a medical oncologist, a doctor who specializes in treating cancer with medication.
Common ways to give systemic therapies include an intravenous (IV) tube placed into a vein using a needle or in a pill or capsule that is swallowed (orally).
The types of systemic therapies used for colorectal cancer include:
- Targeted therapy
Physical, emotional, and social effects of cancer
Cancer and its treatment cause physical symptoms and side effects, as well as emotional, social, and financial effects. Managing all of these effects is called palliative care or supportive care. It is an important part of your care that is included along with treatments intended to slow, stop, or eliminate cancer.
Palliative care focuses on improving how you feel during treatment by managing symptoms and supporting patients and their families with other, non-medical needs. Any person, regardless of age or type and stage of cancer, may receive this type of care. And it often works best when it is started right after a cancer diagnosis. People who receive palliative care along with treatment for the cancer often have less severe symptoms, better quality of life, and report they are more satisfied with treatment.
Palliative treatments vary widely and often include medication, nutritional changes, relaxation techniques, emotional and spiritual support, and other therapies. You may also receive palliative treatments similar to those meant to get rid of the cancer, such as chemotherapy, surgery, or radiation therapy.
Before treatment begins, talk with your doctor about the goals of each treatment in the treatment plan. You should also talk about the possible side effects of the specific treatment plan and palliative care options.
During treatment, your health care team may ask you to answer questions about your symptoms and side effects and to describe each problem. Be sure to tell the health care team if you are experiencing a problem. This helps the health care team treat any symptoms and side effects as quickly as possible. It can also help prevent more serious problems in the future.
Remission and the chance of recurrence
A remission is when cancer cannot be detected in the body and there are no symptoms. This may also be called having “no evidence of disease” or NED.
A remission may be temporary or permanent. This uncertainty causes many people to worry that the cancer will come back. While many remissions are permanent, it is important to talk with your doctor about the possibility of the cancer returning. Understanding your risk of recurrence and the treatment options may help you feel more prepared if the cancer does return.
If the cancer returns after the original treatment, it is called recurrent cancer. It may come back in the same place (called a local recurrence), nearby (regional recurrence), or in another place (distant recurrence).
When this occurs, a new cycle of testing will begin again to learn as much as possible about the recurrence. After this testing is done, you and your doctor will talk about the treatment options. Often the treatment plan will include the treatments described above, such as surgery, chemotherapy, and radiation therapy, but they may be used in a different combination or given at a different pace. Your doctor may suggest clinical trials that are studying new ways to treat this type of recurrent cancer. Generally, the treatment options for recurrent cancer are the same as those for metastatic cancer (see above) and include surgery, radiation therapy, and chemotherapy. Whichever treatment plan you choose, palliative care will be important for relieving symptoms and side effects.
People with recurrent cancer often experience emotions such as disbelief or fear. You are encouraged to talk with the health care team about these feelings and ask about support services to help you cope..
Dr. Rakesh Rai. MS, FRCS, MD, CCST, ASTS Fellow