The diagnosis process
Anal cancer often is found after there are symptoms. Your doctor may do an exam and other tests to diagnose anal cancer.
MSK’s GUIDE TO
Anal Cancer Diagnosis, Types & Stages
Overview of anal cancer diagnosis
At MSK, treatment for anal cancer starts with a correct diagnosis. We’re here to help you take the first steps toward getting the best cancer care.
You may be reading this because you’re worried you may have anal cancer. Maybe you’re waiting for test results. Or perhaps you or someone you care about just learned they have anal cancer.
This guide will help you understand how anal cancer is diagnosed and what your diagnosis means. Learning as much as you can may help you feel ready to talk with doctors about your care.
Understanding your diagnosis
Your diagnosis most often will describe where the cancer started, its type, and if it has spread. We use this information to create your care plan.
Request an appointment
Talk with an MSK Care Advisor. We're here 24 hours a day, 7 days a week.
The diagnosis process
How is anal cancer diagnosed?
We diagnose anal cancer in a few ways. It’s often found during a procedure for another problem, such as a hemorrhoid.
Anal cancer often is found after there are symptoms. If your healthcare provider thinks you may have anal cancer, they may ask you to see an expert in colorectal cancers. They can order tests to confirm if you have anal cancer.
If you have signs or symptoms of anal cancer, your diagnosis process may look like this:
- Health record: If you have symptoms, your primary care provider will review your health record. They’ll ask questions to find out if you have any anal cancer risk factors. They may send you to an expert, such as a gastroenterologist. A gastroenterologist (GAS-troh-EN-teh-RAH-loh-jist) is a doctor with special training in the gastrointestinal (GI) system.
- Digital rectal exam and physical exam: Your doctor will use a finger to feel for any tumors or areas that are not normal in your anus and rectum. They may check other parts of your body for health problems that are causing your symptoms. Your healthcare provider may order diagnostic tests. If you have a cervix, they may give you a Pap test or pelvic exam.
- Endoscopic (en-doh-SKAH-pik) tests: These tests use a flexible tube with a camera on the end to look inside the anus and rectum. Examples are a colonoscopy, anoscopy, proctoscopy (rigid sigmoidoscopy), and flexible sigmoidoscopy (sig-MOY-DOS-koh-pee). They’ll look for lumps or tissue that does not look normal.
- Biopsy: A biopsy is a procedure to remove a small piece of tissue. For anal cancer, the biopsy may be done with anesthesia (medicine to make you sleep). A pathologist is a doctor who uses a microscope to diagnose disease. They’ll examine your tissue sample under a microscope to see if it has cancer cells. If they find cancer, you will have tests to find the cancer type, such as imaging tests.
- Imaging Tests: If cancer cells are found in your biopsy tissue sample, your doctor will order imaging tests. They may include a computed tomography (CT) scan, magnetic resonance imaging (MRI), and positron emission tomography (PET) scan. These tests can show if the cancer has spread to other parts of your body.
At MSK, our goal is to get you through this challenging time and back to your life. We’ve treated thousands of patients who, like you, came in with anxiety, hopes, and uncertainty about the future.
Understanding your diagnosis
Learning you have anal cancer can be overwhelming. You’ll hear many medical terms you've never heard before. We’re here to help you understand what they mean and why they matter.
The information in your anal cancer diagnosis describes important details about the type of cancer you have. Your doctors use that information to create the best plan of care for you.
Video | 3:32
MSK patients offer helpful tips on becoming a new patient
Newly diagnosed? Hear advice from our patients.
Michael:
You have a diagnosis of cancer, and there's all this fear and there's apprehension and you're nervous and you're scared. You've got surgery in front of you. You've got quality of life issues ahead of you. What I wish I had known was that you can come out the other side of this journey.
Lorena:
When I received the news that I had cancer, it was devastating and I was lost, completely lost.
Ming:
You are meeting with a lot of different people, so what I would really recommend to patients is just do your best to take notes.
Michael:
Come to the appointment prepared. Come with questions.
Norma:
I had questions about my recovery. I had questions about the possibility of chemo. I was placed on a clinical trial, and I had questions about that.
Michael:
Prior to coming to MSK, my wife and I had been to a variety of different doctors, and we got a lot of different answers and no clear direction. It was the first time that a definitive plan was put in place where I actually had a recommendation of which way to go.
Ming:
My care team consisted of doctors, social workers, nurses.
Michael:
It's not just one doctor you're dealing with. You're dealing with all of MSK and their entire team approach to your care.
Lorena:
The way they greet me, it was just overwhelming. I was so happy. It was 100% personalized for me.
Norma:
I was told to expect patient-centered care and I kind of felt that from the beginning, from that first day that I walked in.
Ming:
There were even people there just to hang out with me and to kill time. If you need something, ask. And even if it's something small like, “Nothing tastes good,” or “Everything tastes awful and I can't eat any of this,” it's important to tell someone and they can help you address your needs as a patient
Lorena:
One of the programs that I found helpful was Integrated Medicine. For example, acupuncture. It helped me to calm down; and then after the treatment, it managed the pain.
Norma:
I immediately used the nutrition program because it was amazing. I used their PT program. I used their Visible Ink program, which is wonderful and it gives you tremendous emotional support.
Lorena:
Another thing that is very helpful is the MSK Patient Portal. You can set up appointments. You can request prescriptions. You can also use the portal for a telemedicine visit. On the days that you don't have any energy, telemedicine is there for you. There is no difference at all between being seen in person or telemedicine.
Norma:
I never felt that I couldn't call someone, even if it was the doctor's nurse, and just talk.
Ming:
The silver lining from being diagnosed with cancer is I taught myself how to be positive.
Lorena:
This experience taught me to live in the moment, and you learn how to live life in a better way.
Here is some of the information your diagnosis may include:
spreading
Where the anal cancer started
Anal cancer starts in the anus’ tissues or in the cells of the inside lining of the anus.
Where the anal cancer started
Up Next
If the anal cancer is
If the anal cancer is spreading
Some anal tumors stay in the place where they started, but others can metastasize (spread) to other areas.
If the anal cancer is spreading
The stage, which explains the tumor’s size, location, and how far it has spread
The stage tells us how advanced the anal cancer is and guides treatment. There are 5 stages, from 0 to 4 (0 to IV). The lower the number, the less the anal cancer has spread.
The stage, which explains the tumor’s size, location, and how far it has spread
MSK Recommends
Bring these questions to your next appointment
When you learn you have anal cancer, you’ll have many questions for your cancer doctor at your first visit. Talking about treatment options with your doctor can help you feel better prepared to make decisions about your care.
- What type of anal cancer do I have, and what stage is it?
- Did I have all the scans I need to learn the stage?
- What genetic testing do you offer for anal cancer?
- What are the best treatment options for the type and stage of anal cancer I have?
- When can I start treatment?
- Can I get treatment at MSK locations close to my home?
- What are the risks and side effects of anal cancer treatment?
- Are there new anal cancer drugs I can try?
- Will I need more tests before treatment starts?
- What experience do you have in treating my type of cancer?
- How will MSK help me recover after treatment?
- Will I get side effects from treatment? How can I manage them?
Types of anal cancer
What are the types of anal cancer?
There are a few types of anal cancer. We’re experienced in treating them all, from the most common to the most rare. This information describes each kind of anal cancer and explains how we classify (sort) them.
Most people who are diagnosed with anal cancer have a type called squamous cell carcinoma. There are other rarer tumor types, too.
Squamous (SKWAY-mus) cell carcinoma (KAR-sih-NOH-muh) is the most common type of anal cancer. About 9 out of every 10 anal cancers start in squamous cells that line the outer layer of the anus. If found early, squamous cell carcinoma often is very treatable.
Adenocarcinoma (A-deh-noh-KAR-sih-NOH-muh) is in the upper part of the anus. Adenocarcinoma anal cancer forms in glandular tissue, which lines some organs.
Basal cell carcinoma is in the skin around the anus and is a very rare type of anal cancer. Surgery is the most common treatment for basal cell carcinoma in the anus.
Melanoma is a very rare type of anal cancer that often is found at a later stage. It can be very hard to spot.
MSK RECOMMENDS
The human papillomavirus (HPV) vaccine has worked well to reduce HPV infections for some 20 years. Still, HPV is very common. When cancer is linked to HPV, some people feel they did something wrong to cause cancer. MSK explains how to talk with people about a cancer diagnosis linked to HPV.
Anal cancer stages 0, 1, 2, 3, and 4
The cancer stage describes traits such as the tumor’s size, whether it spread, and where it spread. Staging tells us how advanced the cancer is. The stage guides the choice of treatment.
There are 5 stages of anal cancer, from 0 to 4 (0 to IV). The lower the number, the less the cancer has spread.
Knowing the stage of the cancer helps you and your doctor decide on the best treatment options for you.
The stage is based on:
- The size and location of the original tumor (also called the primary tumor).
- If the cancer has spread to nearby lymph nodes.
- If the cancer has spread to other parts of the body, such as the lungs or liver.
Your doctor may use letters and numbers from the TNM system to describe the stage:
- T is the size of the tumor.
- N is whether the cancer has spread to the lymph nodes.
- M is whether the cancer has metastasized (spread) to other areas.
N0 means cancer is not in lymph nodes, while N1, N2 or N3 means it’s spread to nodes. M0 means cancer has not spread, while M1 means it’s spread to distant organs, muscles, or bones.
What are the stages of anal cancer?
-
Stage 0
-
Stage 1
-
Stage 2
-
Stage 3
-
Stage 4
Last updated December 2, 2025
Learn about our Health Information Policy.