Anal Cancer Diagnosis
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 anal cancer.
The following tests are used to diagnose anal cancer and find out if it has spread to different parts of the body. They may also be used to learn how the cancer responds to treatment.
Your doctor will first conduct one or more of the following tests to determine if you have anal cancer. These tests can include:
Physical examinations
Patients with suspected anal cancer will undergo a physical exam to look for signs of the disease. This exam should include:
- Digital rectal exam: The doctor inserts a gloved, lubricated finger into the patient's anus to feel for any abnormalities. This is part of a broader physical exam performed by doctors.
- Pelvic Exam: Pelvic exams are only performed on female patients. They can help determine if the cancer has spread to the vagina, cervix, uterus or ovaries. Usually, the doctor will use a small metal tool called a speculum to look for signs of disease. The patient may also undergo a Pap smear, a procedure that tests for cancer cells in the cervix and upper vagina.
Biopsy
If the physical exam indicates anal cancer, the doctor should order a biopsy. A biopsy is the only way to definitively diagnose anal cancer. During a biopsy, a small tissue sample is removed and examined under a microscope for the presence of cancer cells. There are several different ways doctors can remove suspected anal cancer tissue, including:
- Anoscopy: A short hollow tube is inserted into the anal canal [GG1] 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, allowing for visual examination of the anus and rectum. The proctoscope also has tools that can also be used take a tissue sample for a biopsy.
- 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) and retrieve tissue for a biopsy.
- Flexible sigmoidoscopy: Similar to a colonoscopy, this procedure uses a flexible tube equipped with a light and camera, but only the rectum, anus and last part of the colon are examined.
- Fine-needle aspiration biopsy: Cancer often spreads first to the lymph nodes. 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. This may help the doctor decide what areas to treat with radiation therapy.
You may have to prepare in advance to undergo these tests. For instance, you may be asked to change your diet or take a laxative shortly before the biopsy. Talk to your doctor about what test is best for you and how to prepare.
Imaging exams
Imaging exams look inside the body for cancer. They are used to examine the area around the tumor. They can also look for the spread of the disease to other parts of the body. Imaging exams for anal cancer include:
- 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.
- Computed tomography (CT scan): 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.
- Magnetic resonance imaging (MRI) scan: An MRI uses strong magnets and radio waves to create a detailed image of the body. Your doctor can use this image to see the extent of the cancer in the anus/rectum and to see if you have swollen lymph nodes, which may indicate the cancer has spread.
- PET/CT (positron emission tomography/computed tomography) scan: This test can help your doctor find cancerous tumor cells throughout the body. 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 locations of malignant tumors.
- Chest X-ray: A standard X-ray of the chest can show if the cancer has spread to your lungs.
Learn more about imaging exams.
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