Your gift is 100% tax deductible
Anal Cancer Early Detection, Diagnosis, and Staging
Know the signs and symptoms of anal cancer. Find out how anal cancer is tested for, diagnosed, and staged.
Can anal cancer be found early?
Many anal cancers can be found early. Early anal cancers often have signs and symptoms that lead people to see a doctor. Unfortunately, some anal cancers may not cause symptoms until they reach an advanced stage.
Anal cancers develop in a part of the digestive tract that your doctor can easily see. A digital rectal exam (DRE) can find some cases of anal cancer early. During this exam, the doctor inserts a gloved, lubricated finger into the anus to feel for unusual lumps or growths. This test is sometimes used to look for prostate cancer in men (because the prostate gland can be felt through the rectum). The rectal exam is also done routinely as part of a pelvic exam on women.
Finding anal cancer early depends on the location and type of anal cancer. Cancers that begin higher up in the anal canal are less likely to cause symptoms and are less likely to be found early. Anal melanomas tend to spread earlier than other anal cancers, making them harder to diagnose early.
Screening people at high risk
Looking for a disease like cancer in someone with no symptoms is called screening. The goal of screening is to find cancer early, when treatment is likely to be most helpful. Anal cancer is not common in the United States, so screening the general public for anal cancer is not widely recommended at this time.
Still, some people at increased risk for anal intraepithelial neoplasia[ (AIN, a potentially precancerous condition) and anal cancer might benefit from screening. This includes men who have sex with men (regardless of HIV status), persons who have had penile cancer, cervical cancer, vaginal cancer, or vulvar cancer, anyone who is HIV-positive, and anyone who is immunocompromised (such as people who have received an organ transplant or take long-term steroids). Some experts also recommend screening for anyone with a history of anal warts and women older than 45 years old who are HPV-16 positive.
For these people, some experts recommend screening with regular anal cytology testing (also known as an anal Pap test or anal Pap smear because it is much like a Pap test for cervical cancer). For this test, the anal lining is swabbed, and cells that come off on the swab are looked at closely in the lab. The anal Pap test can then be followed by a DRE or a procedure called an anoscopy.
The anal Pap test has not been studied enough to know how often it should be done, or if it reduces the risk of anal cancer by catching AIN early. Some experts recommend that the test be done every year in at-risk people who are HIV-positive, and every 2 to 3 years in at-risk people who are HIV-negative. But there is no widespread agreement on the best screening schedule, or even exactly which groups of people can benefit from screening.
Tests for anal cancer
Screening tests, such as the digital rectal exam and/or anal Pap test diagnosis some people at high risk for anal cancer. Sometimes a doctor will find anal cancer during a routine physical exam or during a minor procedure, such as removing a hemorrhoid. Treating cancers found this way is often very effective because the tumors are found early. This means they're small and haven't spread.
Most of the time, however, anal cancers are found because a person is having symptoms. If cancer is found, more tests probably will be done to help determine the extent (stage) of the cancer.
If you are having symptoms that might be caused by anal cancer, the doctor will ask about your medical history to check for possible risk factors and to learn more about your symptoms.
Your doctor will also examine you, looking for signs of anal cancer or other health problems. For women, this will include a pelvic exam and a Pap test. A digital rectal exam will probably be done, too (a gloved, lubricated finger feels for lumps or other changes in your anus and rectum). The groin area will be felt to check for any large lymph nodes.
If problems or changes are found, your doctor might order more exams or tests to help find the cause. If you're being seen by your primary care doctor, you might be referred to a specialist such as a colorectal surgeon or a gastroenterologist (doctors specializing in diseases of the colon, rectum, and anus) for more tests and if needed, treatment.
Complete blood count (CBC): This test measures the different types of cells in your blood. It can show if you have anemia (too few red blood cells). Some people with anal cancer become anemic because the tumor has been bleeding for a long time.
Liver enzymes: You may also have a blood test to check your liver function, because anal cancer can spread to the liver.
HIV test: If you have been diagnosed with anal cancer, specifically squamous cell anal cancer, your doctor may check your HIV statuswith a blood test . This information is important because HIV-positive patients might need to start treatment for HIV before starting cancer treatment.
Imaging tests use x-rays, magnetic fields, sound waves, or radioactive substances to create pictures of the inside of your body. Imaging tests may be done for a number of reasons, such as:
- To look at suspicious areas that might be cancer
- To learn how far cancer might have spread
- To help determine if treatment is working
- To look for signs of cancer coming back after treatment
Ultrasound
Ultrasound uses sound waves and their echoes to create images of the inside of the body. A small microphone-like instrument called a transducer gives off sound waves and picks up the echoes as they bounce off organs. The echoes are converted by a computer into an image on a screen.
Endorectal ultrasound: A special transducer is put into the rectum to see how far through the rectal wall a cancer has grown and if it has reached nearby organs or lymph nodes.
Computed tomography (CT) scan
CT scans use x-rays to make detailed cross-sectional images of your body. This is a common test for people with anal cancer. This test can help tell if the cancer has spread into the lymph nodes or to other parts of the body, such as the liver, lungs, or other organs.
Magnetic resonance imaging (MRI)
Like CT scans, MRI scans show detailed images of soft tissues in the body. But MRI scans use radio waves and strong magnets instead of x-rays. A contrast material called gadolinium may be injected into a vein before the scan to get clear pictures. MRI can be used to look at abnormal areas in the liver or the brain and spinal cord that could be cancer spread.
Positron emission tomography (PET) scan
For a PET scan, a slightly radioactive form of sugar (known as FDG) is injected into your blood. It collects mainly in cancer cells, which makes the cancer show up on the PET scan.
PET/CT scan: A CT scan can show more details than a PET scan, so a PET scan is often combined with a CT scan using a special machine that can do both at the same time. This lets the doctor compare areas of higher radioactivity on the PET scan with the more detailed image of that area on the CT scan.
Endoscopy uses a thin, flexible tube with a light and tiny video camera on the end to look inside part(s) of the body. Many types of endoscopies can be used to look for the cause of anal symptoms.
Anoscopy
The doctor uses a short, hollow, firm tube called an anoscope. It's 3 to 4 inches long and about 1 inch in diameter and may have a light on the end of it. The doctor coats the anoscope with a gel and then gently pushes it into the anus and lower rectum. By shining a light into this tube, the doctor has a clear view of the lining of the lower rectum and anus. Samples from abnormal areas (a biopsy) can be taken at the same time. You will be awake during this test, but it usually is not extremely uncomfortable.
Sigmoidoscopy
The sigmoidoscope is a lot like an anoscope, except longer (about 10 inches long). It lets the doctor see the anus, rectum, and the lower part of the sigmoid colon. You might need to take laxatives or have an enema before this test to make sure your bowels are empty so the doctor can see any abnormal areas clearly.
Colonoscopy
A colonoscopy allows the doctor to see the anus, rectum, and entire colon. It can be used to get tissue samples from inside the anal canal, the rectum, and colon (described below under Biopsy). Drugs may be used to make you sleepy during these tests.
If a change or growth is seen during an endoscopic exam, your doctor will need to take out a piece of it to see if it's cancer. This is called a biopsy. If the growth is in the anal canal, this can often be done through the scope itself. Drugs may be used to numb the area before the biopsy is taken. Then, a small piece of the tissue is cut out and sent to the lab. If the tumor is very small, your doctor might try to remove the entire tumor during the biopsy.
A pathologist will look at the tissue sample with a microscope. If there is cancer, the pathologist will send back a report with the cell type and other details of the cancer, including whether it is related to an HPV infection.
Anal cancer sometimes spreads to nearby lymph nodes (bean-sized collections of immune system cells). Swollen lymph nodes in the groin can be a sign that cancer has spread. Lymph nodes may also become swollen from an infection. Biopsies may be needed to check for cancer spread to nearby lymph nodes.
There are many different ways to do a biopsy. Fine-needle aspiration (FNA) is often used to check lymph nodes that might have cancer in them. To do this, a small sample of tissue is taken out of the lymph node using a thin, hollow needle. A pathologist checks this tissue for cancer cells. If cancer is found in a lymph node, surgery may be done to remove the lymph nodes in that area.
Stages and outlook (prognosis ) for anal cancer
After a cancer diagnosis, staging provides important information about how much cancer is in the body and how it might respond to treatment.
Questions to ask when you're told you have anal cancer
Being able to have honest, open discussions with your cancer care team and getting your questions answered is important, so that you can make informed treatment and life decisions. For instance, consider these questions:
- What kind of anal cancer do I have?
- Has my cancer spread beyond where it started?
- What is the stage of my cancer and what does this mean in my case?
- Will I need other tests before we can decide on treatment?
- Will I need to see other doctors?
- If I’m concerned about the costs and insurance coverage for my diagnosis and treatment, who can help me?
- Written by
- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
Czito BG, Ahmed S, Kalady MF, and Eng C. Chapter 64: Cancer of the anal region. In: DeVita VT, Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles & Practice of Oncology. 11th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2019.
Goodman KA, Kachnic LA, Czito BG. Chapter 76: Cancer of the anal canal. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 6th ed. Philadelphia, Pa. Elsevier: 2020.
National Cancer Institute Physician Data Query (PDQ). Anal Cancer Treatment. Updated May 16,2025. Accessed at https://www.cancer.gov/types/anal/patient/anal-treatment-pdq#_1 on August 20,2025.
National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Anal Carcinoma. V.4.2025. Accessed at www.nccn.org/professionals/physician_gls/pdf/anal.pdf on August 20, 2025.
Last Revised: November 20, 2025
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.
American Cancer Society Emails
Sign up to stay up-to-date with news, valuable information, and ways to get involved with the American Cancer Society.
