If you have symptoms that may signal anal cancer, your doctor will examine you and ask you questions about your health, your lifestyle, including smoking and drinking habits, and your family history. Many anal cancer cases are related to human papillomavirus (HPV) infection, so your doctor may ask if you have been exposed to HPV or received the HPV vaccination. These and other factors may put you at an increased risk for colorectal cancer and anal cancer. Your doctor needs to know about your risk factors when screening you for cancer.
Diagnosing Anal Cancer
Your doctor will first conduct one or more of the following tests to determine if you have anal cancer. These tests can include:
- Digital Rectal Exam: The doctor will insert a gloved, lubricated finger into your anus and feel for any abnormalities.
- Anoscopy: A short tube with a camera is inserted into the anal canal anus and lower rectum. This allows the doctor to examine the anus for any visible abnormalities. Additionally, the doctor may remove a small sample of tissue (a biopsy) from the anus to undergo further testing.
- Proctoscopy (Rigid Sigmoidoscopy): A hollow tube, called a proctoscope, is inserted into your anal canal to your rectum. Proctoscopes tend to be longer than anoscopes. The proctoscope is equipped with a light and camera, allowing for visual examination of the anus and rectum. The proctoscope can also be used to biopsy tissue from the anus.
- Colonoscopy: a long, flexible tube, called a colonoscope, is inserted into the rectum. The colonoscope is equipped with a light and camera that allow the doctor to examine any part of your colon (large intestine). The colonoscope can also be used to biopsy tissue.
- Biopsy: if your doctor discovers any abnormalities in your anus or rectum, he or she may remove a small sample of tissue (a biopsy) to undergo further testing in a laboratory. Looking at the tissue under a microscope allows your doctor to determine if there are cancer cells present. Usually, the devices used in the examination, such as an anoscope, proctoscope, or colonoscope, can collect these tissue samples from your anus.
- In some cases, a biopsy of your anus may reveal abnormal cells that are not cancerous. This is called anal intraepithelial neoplasia, and it means that abnormal cells are lining your anus. While these cells are not cancerous, they may eventually develop into cancer and so should be monitored regularly.
- Double contrast barium enema (DCBE): Barium is a chemical that allows the bowel lining to show up on an X-ray. You will be given an enema with a barium solution, and then X-rays will be taken.
- Endo-anal or endorectal ultrasound (endosonography): An endoscope is inserted into the anus. A probe at the end of the endoscope bounces high-energy sound waves (ultrasound) off organs to make an image (sonogram). Your doctor can use this image to view abnormalities of the anus and rectum.
- Virtual colonoscopy or CT (computed tomography) colonoscopy: a virtual colonoscopy involves using a CT scanner, to create a 3D image of your abdominal organs. This allows the doctor to see the inside of your large intestine and rectum without having to insert a colonoscope.
- You may have to prepare in advance to undergo these tests. For instance, your doctor may ask that you change your diet shortly before the exam, or you may be administered a laxative or enema prior to examination. Talk to your doctor about what test is best for you and how to prepare.
Determining if your Cancer has Spread
If you are diagnosed with anal cancer, you may have to undergo additional tests to determine if your cancer has spread (metastasized). A metastatic tumor is a cancerous tumor that has spread from its original location to other parts of the body. In particular, anal cancer can spread to nearby lymph nodes, blood vessels, or through surrounding healthy tissue. Whether and how far the cancer has spread determines what treatment options are right for you.
There are a few different tests to determine if your cancer has spread:
- CT (computed tomography) scan (also called a CAT scans): a CT scanner creates detailed, cross-sectional images of various parts of your body. Your doctor will examine these images to see if the cancer has spread to your lymph nodes or other organs.
- MRI (magnetic resonance imaging) scans: An MRI uses strong magnets and radio waves to create a detailed image of the body. Your doctor can use this image to see if you have swollen lymph nodes, which may indicate the cancer has spread.
- PET/CT (positron emission tomography) scans: This test can help your doctor find cancerous tumor cells. For the exam, you will be injected with a safe form of radioactive sugar. Malignant tumor cells grow rapidly and require lots of energy, so these cells will absorb more of the radioactive sugar. You will then undergo the PET scan, which will create a picture showing where the radioactive glucose is being used in the body. Bright spots on the image indicate areas where there is a lot of sugar uptake, which can indicate the location of malignant tumors.
- The machine used for the PET scan can usually also perform a CT scan. CT scans are more detailed. Your doctor can compare the results of the two scans to get a clearer idea of what is happening in your body.
- Chest X-Ray: Your doctor may perform a standard X-Ray of your chest to see the organs and bones inside your chest. If the cancer has spread to your lungs, it will be visible on the X-Ray.
- Pelvic Exam: Your doctor may perform a pelvic exam to see if the cancer has spread to your vagina, cervix, uterus, or ovaries. Usually, the doctor will use a small metal tool called a speculum to look for signs of disease. He or she may also perform a Pap smear, a procedure used to test for cancer cells in the cervix and upper vagina.
- Fine-needle aspiration biopsy: In a fine-needle aspiration biopsy, a tiny needle is placed into a lymph node, and cells are removed and looked at with a microscope. A positive lymph node biopsy indicates the cancer has spread to your lymph nodes. This may help the doctor decide what areas to treat with radiation therapy.
Learn more about anal cancer treatment.
Anal Cancer Staging
If you are diagnosed with anal cancer, your doctor will determine the stage of the disease. Staging is a way of talking about how much disease is in the body and where it has spread. This information helps the doctor treat the cancer.
Once the staging classification is determined, it stays the same even if treatment is successful or the cancer spreads.
Anal Cancer Stages
(source: National Cancer Institute)
Stage 1: Cancer has formed. The tumor is 2 centimeters or smaller.
Stage 2: Tumor is larger than 2 centimeters but not greater than or equal to 5 centimeters
Stage 3A: Tumor is 5 centimeters or greater and/or has spread to either:
- Lymph nodes near the rectum
- Nearby organs, such as the vagina, urethra or bladder
Stage 3B: Tumor is 5 centimeters or greater and/or may be any size and has spread to:
- Nearby organs and lymph nodes near the rectum
- Lymph nodes on one side of the pelvis and/or groin and may have spread to nearby organs
- Lymph nodes near the rectum and in the groin and/or lymph nodes on both sides of the pelvis and/or groin and may have spread to nearby organs
Stage 4: Tumor may be any size and may have spread to lymph nodes or nearby organs and has spread to distant parts of the body.
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