Cancer screening exams can help find rectal cancer at its earliest stage when the chances for successful treatment, optimal outcomes and fewer side effects are greatest. These tests are usually done when a patient is healthy and has no specific symptoms.
Not only are expert cancer researchers at the OSUCCC – James continually working to detect and diagnose rectal cancer early, but they are also developing additional tests to detect and diagnose cancer even earlier, leading to improved outcomes, faster responses and fewer side effects.
Adults who are not at an elevated risk of rectal cancer should begin having screening exams at age 50. People who are at higher risk — because of a personal history of colon or rectal cancer, colorectal polyps or inflammatory bowel disease — should be screened before they turn 50.
In addition, people who have a family history of colorectal cancer, colon polyps or of certain hereditary syndromes that put them at higher risk for colorectal cancer should also be screened before they turn 50.
Special genetic screening for Lynch syndrome, also called hereditary nonpolyposis colorectal cancer, identifies the gene responsible for the disease early.
Rectal Cancer Risk Factors
A risk factor is anything that increases your risk of getting cancer. Risk factors for rectal cancer include:
- Being 40 or older
- A history of colon cancer or rectal cancer
- A history of colorectal adenomas (noncancerous tumors)
- Previous Crohn’s disease or ulcerative colitis
- Previous cancer in the ovary, breast or endometrium
- Colon or rectal cancer in a close family relative (parent, brother, sister or child)
The presence of risk factors does not necessarily mean you have rectal cancer. But if you have risk factors, you should discuss them with your doctor.
The following screening exams are some of the tests that may be used to screen for rectal cancer in patients with no symptoms and patients with risk factors.
Fetal Occult Blood Test
A stool sample is analyzed for occult blood, or blood that only can be seen using a microscope. Patients collect test samples on special cards at home following instructions from a physician or lab.
Fecal Immunochemical Test
This is a newer test that identifies blood in stool using a chemical that reacts to a protein in red blood cells. The exam can be completed without dietary restrictions usually required for a fecal occult blood test.
A radiologist takes a series of X-ray images of the lower digestive tract after placing a special liquid called barium in the rectum to highlight the lining of the intestine.
Using a tube that is slightly longer than a sigmoidoscope, a specially trained surgeon identifies any polyps or other abnormal signs in your colon and rectum. Patients must prepare for colonoscopies for one day to several days in advance.
Also called CT colonoscopy, this exam uses computed tomography to take X-ray images of the colon and rectum using a scanner that rotates around the patient. A connected computer and software produce detailed images, often in three dimensions, to reveal polyps or signs of cancer.
A physician analyzes the colon and rectum using a thin, flexible tube with a lighted end called a sigmoidoscope. A camera on the end of the scope can display images of the inside of the rectum, and a special tool on the scope can assist in polyp or tissue removal.
Samples of a patient’s blood, a cheek cell collected in mouthwash or a stool sample can be analyzed to look for changes in genes that indicate colorectal cancer.
A digital rectal examination may be performed as part of a physical examination and for your physician to evaluate rectal cancer. It is not recommended as a single screening examination for rectal cancer.
Diagnosing Rectal Cancer
If you are diagnosed with rectal cancer, your doctor may perform a complete physical examination and additional tests.
Many of the exams used to screen for rectal cancer — such as an occult blood test, colonscopy, barium enema exam or sigmoidoscopy — also are used in diagnosing the disease.
Colonoscopy is the most important imaging exam used to analyze the colon and rectum and to diagnose polyps and rectal cancer.
Blood tests that analyze samples of blood drawn from a patient can identify signs that indicate colorectal cancer. A complete blood count measures various blood cells and can show that a patient has anemia, which may occur when a colorectal tumor bleeds for a long period of time.
A biopsy confirms a rectal cancer diagnosis. Sample tissue from the rectum is analyzed under a microscope by a specially trained pathologist. A doctor can obtain the tissue during a colonoscopy.
Analyzing genes of certain cancer cells from a rectal tumor biopsy can assist in planning targeted treatment for patients with rectal cancer. A test called a reverse-transcriptase polymerase chain reaction test analyzes cells to identify changes in structures and functions of genes.
Immunohistochemistry identifies antigens in cells to classify types of rectal cancer.
Tests Used for Staging Rectal Cancer
Once a patient receives a rectal cancer diagnosis, a physician may order tests to determine whether the cancer has spread to other parts of the body and to help stage the cancer. These include:
Computed Tomography (CT) Scan
The X-ray examination produces a series of detailed images taken from different angles. A computer linked to an X-ray machine revolves around your body to create multidimensional images.
Positron Emission Tomography (PET) Scan
A PET scan is an imaging examination used to find malignant tumor cells in the body. A small amount of radioactive tracer is injected into your vein. The PET scanner rotates around your body, and any areas where the tracer concentrates are highlighted. These areas are more active and usually indicate cancerous cells.
Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) uses a high-powered magnet and radio waves to produce detailed images of the body.
Ultrasound uses sound waves instead of X-rays to evaluate the organs and spaces inside the abdomen for possible spread of the rectal cancer. With endorectal ultrasound, the ultrasound probe can be inserted into the rectum.
Angiography is a type of X-ray procedure that evaluates a patient’s arteries and blood vessels to determine if rectal cancer has spread to the liver.
X-rays produce images of the tissues and organs inside the chest, especially the lungs.
Lymph Node Biopsy
A lymph node near the rectal cancer might be removed to analyze under a microscope to look for cancer cells.
During surgery, a physician removes the rectal tumor and analyzes how far the cancer has spread within the rectum.
Tumor Marker Analysis
A sample of blood is analyzed for substances made by organs, tissues or tumor cells in the body that are linked to specific types of cancer. These are called tumor markers.
Carcinoembryonic antigen (CEA) and CA 19-9 are associated with colorectal cancer and other diseases.
Staging Rectal Cancer
If you receive a rectal cancer diagnosis, staging is a way of determining the amount and location of your cancer. This information helps your team of specialists plan the best treatment. The staging classification remains the same throughout treatment.
Rectal cancer can be diagnosed in one of five stages:
Stage 0 is called carcinoma in situ, when abnormal cells are found in the mucosa, or innermost layer, of the rectal wall. These abnormal cells may become cancer and spread.
Cancer has formed in the mucosa of the rectal wall and has spread to the submucosa (layer of tissue beneath the mucosa). Cancer may have spread to the rectal wall’s muscle layer.
Stage II is divided into three substages, depending on where the cancer has spread:
Cancer has spread through the rectal wall’s muscle layer to the serosa (outermost layer) of the rectal wall.
Cancer has spread through the serosa of the rectal wall, but has not spread to nearby organs.
Cancer has spread through the serosa of the rectal wall to nearby organs.
Stage III rectal cancer is divided into three substages, depending on where the cancer has spread.
- Cancer may have spread through the mucosa of the rectal wall to the submucosa and may have spread to the muscle layer of the rectal wall; cancer has spread to at least 1 but not more than 3 nearby lymph nodes, or cancer cells have formed in tissues near the lymph nodes; or
- Cancer has spread through the mucosa of the rectal wall to the submucosa; cancer has spread to at least 4 but not more than 6 nearby lymph nodes
- Cancer has spread through the muscle layer of the rectal wall to the serosa of the rectal wall or has spread through the serosa but not to nearby organs; cancer has spread to at least 1 but not more than 3 nearby lymph nodes, or cancer cells have formed in tissues near the lymph nodes; or
- Cancer has spread to the muscle layer of the rectal wall or to the serosa of the rectal wall; cancer has spread to at least 4 but not more than 6 nearby lymph nodes; or
- Cancer has spread through the mucosa of the rectal wall to the submucosa and may have spread to the muscle layer of the rectal wall; cancer has spread to 7 or more nearby lymph nodes
- Cancer has spread through the serosa of the rectal wall but has not spread to nearby organs; cancer has spread to at least 4 but not more than 6 nearby lymph nodes; or
- Cancer has spread through the muscle layer of the rectal wall to the serosa of the rectal wall, or has spread through the serosa but has not spread to nearby organs; cancer has spread to 7 or more nearby lymph nodes; or
- Cancer has spread through the serosa of the rectal wall and has spread to nearby organs; cancer has spread to 1 or more nearby lymph nodes or cancer cells have formed in tissues near the lymph nodes
There are two substages to Stage IV rectal cancer.
Cancer may have spread through the rectal wall and may have spread to nearby organs or lymph nodes. Cancer has spread to one organ that is not near the rectum, such as the liver, lung or ovary or to a distant lymph node.
Cancer may have spread through the rectal wall and may have spread to nearby organs or lymph nodes. Cancer has spread to more than one organ that is not near the rectum or into the lining of the abdominal wall.
(Source: National Cancer Institute)
If you have received a rectal cancer diagnosis, or if you want a second opinion or just want to speak to a rectal cancer specialist, we are here to help you. Call 800-293-5066 or 614-293-5066 to make an appointment.