Anal Cancer Diagnosis & Staging

Anal Cancer Diagnosis & Staging

MSK pathologist Jinru Shia looks through a microscope

Jinru Shia is part of a team of pathologists who have expertise in diagnosing anal cancer.

Anal Cancer Diagnosis

We diagnose anal cancer in a few ways. It’s often found during a procedure for another condition, such as a hemorrhoid.

In general, anal cancer often is found after there are symptoms. It is not often found during a regular screening colonoscopy for colorectal cancer.

Your primary care provider should refer you to a specialist for more tests if they think you have anal cancer. It’s very important to choose the best treatment for the disease.

MSK pathologists (doctors who use a microscope to diagnose disease) and radiologists are experts in testing for anal cancer. If your doctor suspects anal cancer, MSK’s pathologists and radiologist can assess tests you already had. They also can do more testing to confirm your diagnosis.

How is anal cancer diagnosed?

Health Record

If you have symptoms, your primary care provider will review your health record. They will ask questions to find out if you have any anal cancer risk factors. They may send you to a specialist, such as a gastroenterologist (a doctor who treats problems of the digestive system).

Digital Rectal Exam and Physical Exam

Your doctor will use a finger to feel for any tumors or abnormal areas in your anus and rectum. They may check other parts of your body for health problems that are causing your symptoms. If you have a cervix, they may give you a Pap test or pelvic exam.


During an anoscopy, your doctor will use a small tool with a light at the end to see inside your anus and rectum. They will look for any lumps or abnormal tissue.

Flexible Sigmoidoscopy

A sigmoidoscopy (sig-MOY-DOS-koh-pee) is a test to look inside your rectum and lower colon. It uses a small camera instead of a light. Your doctor may also do a biopsy, a procedure to remove a small piece of tissue.


A biopsy is a procedure to remove a small piece of tissue. For anal cancer, the biopsy may be performed under anesthesia (medicine to make you sleep). A pathologist will look at the tissue for cancer cells under a microscope. 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.

After you are diagnosed with anal cancer, your doctor will assign a stage to the cancer. Read more about the stages of anal cancer.

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