Cancer type

Anal Cancer

Anal cancer is considered a rare cancer, but the number of patients receiving a diagnosis is growing, especially in the United States. Anal cancers make up around 3% of all GI cancers. Ninety percent of anal cancers are squamous cell anal carcinomas, or SCAC, and most of these cancers are due to the HPV virus. Being vaccinated against HPV lowers the risk of anal cancer.  If caught early, there’s a good chance for survival.

What is anal cancer?

The anus is found at the very end of the large intestine. It’s connected to the rectum through a sphincter. The anus is the last part of the digestive system that poop goes through before it exits the body.

Cancer in the anus forms in the tissues of the anus. This can appear in the lining (mucosa) or in the skin outside of the anus that contains hair follicles and sweat glands. 

While it’s easy to get them confused, anal cancer is not the same thing as rectal cancer; these are two different parts of the body and the tumors that form in each of these areas need unique treatment plans.

Types of anal cancer

The type of anal cancer you have will depend on where it started.

Squamous Cell Anal Carcinoma

The most common type, 90%, of anal cancer is squamous cell anal carcinoma, or SCAC. This cancer begins in flat cells lining the anal canal. Anal cancer treatment guidelines are designed to treat this type of cancer. 

Rare types of anal cancer

A few other rare types of anal cancer include adenocarcinomas, basal cell carcinomas, melanoma, gastrointestinal stromal tumor (GIST), and anal lymphoma. 

Staging anal cancer

If you have anal cancer, you need to know your stage. This helps you understand the size of your tumor, where the cancer is now, and the best treatment plan for your unique situation. 

Anal cancer is staged on a scale from 0-IV (0-4) using the TNM staging system.

‍

Stage NameDescriptionSizeSpread
Stage 0 (carcinoma in situ)Abnormal cells are inside the inner layer of the anus. They may become cancerous and spread to nearby tissue. This is also called “high-grade intraepithelial lesion (HSIL).”N/AInner layer of anus
Stage I (1)Cancer has formed and the tumor is 2 centimeters or smaller.≤ 2 cmLocalized
Stage II (2)This cancer is divided into stages IIA and IIB.VariableLocalized
Stage IIAThe tumor is between 2-5 centimeters.2-5 cmLocalized
Stage IIBThe tumor is larger than 5 centimeters.> 5 cmLocalized
Stage III (3)This cancer is divided into stages IIIA, IIIB, and IIIC.VariableLymph nodes or organs
Stage IIIAThe tumor is 5 centimeters or smaller and has spread to lymph nodes near the anus or groin.≤ 5 cmLymph nodes (Anus/Groin)
Stage IIIBThe tumor is any size and has spread to nearby organs, such as the vagina, urethra, or bladder, but not the lymph nodes.Any sizeNearby Organs (No nodes)
Stage IIICThe tumor is any size and may have spread to nearby organs. Cancer has spread to lymph nodes near the anus or groin.Any sizeOrgans + Lymph nodes
Stage IV (4, also called “metastatic”)The tumor is any size. Cancer may have spread to lymph nodes or nearby organs and it is in other parts of the body, most likely the liver or lungs.Any sizeDistant (Liver/Lungs)
RecurrentAnal cancer has come back after it has been treated.N/AReappearance

‍

What causes anal cancer?

Risk factors put you at a higher risk of getting cancer. Some risk factors can be controlled with lifestyle changes, and others cannot. Just because you have a risk factor, that doesn’t mean you will get anal cancer. 

These are scenarios researchers have found that can increase your risk of getting anal cancer. 

  • HPV infection
  • Weakened immune system (due to HIV, organ transplant, medications, etc.)
  • Smoking
  • Other cancers in the genitals 

Preventing anal cancer

The following steps can help reduce your risk of anal cancer:

  • Get vaccinated for HPV
  • Get screened for anal cancer
  • Treat any HSIL found
  • Stop smoking

How common is anal cancer? 

The 2025 American Cancer Society estimates for anal cancer in the United States are:

About 10,930 new cases (3,560 in men and 7,370 in women)

About 2,030 deaths (780 in men and 1,250 in women)

More and more people are getting anal cancer. The average age of diagnosis is 64 years old. It is slightly more common in women compared to men.

See more anal cancer statistics from the National Cancer Institute’s SEER program. 

What are my odds of surviving it?

Anal cancer is highly treatable if caught early. Doctors use what’s called “survival statistics” to understand the likelihood of a patient beating the disease.

According to the National Cancer Institute, 71% of patients are alive five years after an anal cancer diagnosis.

Survival Statistics

Detailed survival statistics are based off where the cancer is located and if it has spread:

Localized

The cancer hasn’t spread

  • 40% of cases
  • 85% of patients are alive five years after diagnosis

Regional

The cancer spread to nearby lymph nodes

  • 37% of cases
  • 70% of patients are alive five years after diagnosis

Distant

The cancer has spread to lymph nodes and/or organs

  • 14% of cases
  • 36% of patients are alive five years after diagnosis

What types of tests should I expect to undergo?

Doctors will use these tests to diagnose anal cancer:

  • Physical exam with a digital rectal exam 
  • Anoscopy
  • Proctoscopy
  • Endo-anal or endorectal ultrasound
  • Biopsy

Once you’ve been diagnosed, you can expect these tests:

  • CT scan
  • Chest x-ray
  • MRI
  • PET scan
  • Pelvic exam

Ask your doctor about these additional tests:

References

Test Your Biomarkers

Table of Contents

Example H2
Test Your Biomarkers
Resources

NCCN Guidelines for Anal Cancer Treatment

NCI Dictionary of Cancer Terms‍

Doctor Discussion Guide

Learn more

Biomarkers

Emerging

TIL

Tumor-infiltrating lymphocytes (TILs) are currently being studied in clinical trials evaluating response to immunotherapy.
Explore
TIL
Emerging

PD-L1 expression

Currently being studied in clinical trials evaluating response to immunotherapy.
Explore
PD-L1 expression
Emerging

HPV ctDNA

This test is being used in several clinical trials to measure minimal residual disease/recurrence in HPV-driven anal cancer.
Explore
HPV ctDNA
Emerging

PIK3CA

Chromosome 3q amplification is an abnormality found in many squamous cell carcinomas, like anal cancer. Within this region is the PIK3CA gene, which is the most frequently mutated gene in anal cancer. By identifying this mutation, researchers may discover targeted therapies that work on this particular signaling pathway.
Explore
PIK3CA
Emerging

TP53

Indicates if there’s a disruption in the p53 pathway and can differentiate HPV-negative from HPV-positive cancer. It plays a larger role in non-HPV cancers, as it can signal worse outcomes.
Explore
TP53
Actionable

NTRK

Although very rare (less than 1%), there is a targeted therapy option for patients with a NTRK fusion and unresectable or metastatic disease whose cancer grew on or after prior treatment and there are no other treatment options.
Explore
NTRK
Actionable

RET

Although very rare (less than 1%), there is a targeted therapy option for patients with RET fusions and advanced or metastatic disease whose cancer grew on or after prior treatment and there are no other treatment options.
Explore
RET
Actionable

HER2 (ERBB2)

Although rare (1-2%), there is a targeted therapy option for patients with a HER2-positive tumor that’s unresectable or metastatic after prior treatment and there are no other treatment options.
Explore
HER2 (ERBB2)
Actionable

DPYD

A deficiency in the DPYD gene means the body lacks proteins needed to break down 5-FU or capecitabine. This can lead to severe side effects and toxicity. Before you receive these medicines, ask for a DPYD test.
Explore
DPYD
Actionable

BRAF

Although rare (1-5%), there is a targeted therapy option for patients with unresectable or metastatic disease and a BRAF V600E mutation whose cancer grew on or after prior treatment and there are no other treatment options.
Explore
BRAF
Actionable

MSI-H/dMMR

Although very rare (less than 1%), there is an immunotherapy available for patients with unresectable or metastatic tumors with microsatellite instability (MSI-H)/mismatch repair (dMMR) whose cancer grew on or after prior treatment who have no other treatment options.
Explore
MSI-H/dMMR
Actionable

TMB

There is an immunotherapy available for patients with unresectable or metastatic disease and high TMB (8-14% of patients) whose cancer grew on or after prior treatment who have no other treatment options.
Explore
TMB
Actionable

HPV

Two common HPV strains that show up in anal cancer are HPV16 and HPV18. HPV-positive anal cancers may be easier to treat and more responsive to chemoradiation.
Explore
HPV
View all biomarkers
You are not alone

Organizations Specializing in

Anal Cancer

The HPV and Anal Cancer Foundation

Advocacy

Anal Cancer Foundation

Advocacy
Become a member