Expert Care and Treatment for Gastrointestinal Cancers
The Gastrointestinal Center includes medical, surgical, and radiation oncologists, gastroenterologists, radiologists, and pathologists who treat patients at all stages of the disease.
Your care team will collaborate to develop a comprehensive, personalized treatment plan that offers the most advanced therapies and an array of supportive resources.
This comprehensive overview of anal cancer highlights essential information, including its symptoms, causes, risk factors, and treatment options. Dana-Farber’s Gastrointestinal (GI) Cancer Treatment Center offers expert, multidisciplinary care for this rare cancer, with personalized treatment plans that may include chemotherapy, radiation, surgery, and access to clinical trials. Learn about prevention strategies — such as the HPV vaccine — and explore the supportive services available to patients at every stage.
What Is Anal Cancer?
Anal cancer occurs when cancer cells form in the tissues of the anus. The anus is the end of the large intestine and the opening of the rectum to the outside of the body. It is where food exits the body. Anal cancer is a rare cancer that is most often diagnosed in adults over the age of 50 and can impact people of any gender. About 7,000 people are diagnosed with anal cancer each year.
Because anal cancer is rare, it’s important to receive care from an experienced team. Our gastrointestinal cancer experts are skilled in treating anal cancer, helping patients manage side effects, and offering personalized care for lumps around or inside the anus that may raise concerns.
Anal Cancer Symptoms and Causes
Signs and symptoms of anal cancer can include:
Bleeding from the anus
One or more small lumps around the anus
Change in bowel habits (including diarrhea, constipation, or change in frequency)
Itching, pain, or pressure near the anus
Bleeding from the anus may be caused by benign (non-cancerous) conditions, such as hemorrhoids, anal fissures, or anal warts. A lump or hard nodule on the anus could also be the sign of a non-cancerous condition. If you notice anal lumps, experience anal bleeding, or have any of the symptoms above, it’s important to see a doctor so that the cause can be found and treated, if necessary.
The majority of anal squamous cancers — the most common form of anal cancer — are caused by a human papillomavirus (HPV) infection. This is a group of 150 related viruses that infect the surface of the skin, which can include the anus.
HPV is a common viral infection, and nearly everyone will get HPV at some point in their lives. HPV vaccines are effective at preventing the types of human papillomavirus that cause cancer, including anal cancer. Although anal cancer is often linked to HPV infection, anal cancer itself is not a sexually transmitted disease (STD). Understanding this distinction helps reduce stigma and support appropriate screening and care.
Anal Cancer and HPV: Should My Child Get the HPV Vaccine?
Nurse practitioner Susanne Menon highlights the HPV vaccine as a critical tool in preventing HPV-related cancers: cervical, vaginal, vulvar, penile, anal, mouth, and throat.
Anal Cancer Risk and Prevention
Many people have no risk factors for anal cancer. However, some things can increase risk, including:
Having the human papillomavirus (HPV) infection — 95% of people with anal cancer have HPV
A weakened immune system, caused by taking drugs that suppress one’s immune system
Having an organ transplant
A history of cancer, including cervical, vulvar, or vaginal cancer
Engaging in receptive anal sex
A history of genital warts
Smoking
People who think they may be at risk should discuss it with their doctor. While there is no way to completely prevent anal cancer, taking the following precautions may reduce your risk:
Receive the HPV vaccine. This safe and effective shot is recommended for children starting at age nine and adults up to age 45.
Practice safer sex.
Get screened regularly if you have HIV or other immune problems.
How to Be Tested for Anal Cancer
In addition to considering a patient’s medical history and assessing their risk factors, the following tests and procedures may be used to diagnose anal cancer, especially when a lump is noticed inside or near the anus:
Physical exam
Digital rectal exam — a finger exam of the anus
Anoscopy or endoscopy — procedures used to view the inside of the intestinal tract
Imaging tests, including FDG PET-CT, and in some cases, a CT scan or an MRI
Examination of lymph nodes in the groin to evaluate possible spread, since the groin area is the most common area for anal cancer to spread
Biopsy
Patients receiving care at another hospital may be interested in a second opinion. Dana-Farber's Second Opinion Program is available for those who are newly diagnosed, whose condition has changed, or whose care team recommends a new treatment plan. Second opinion appointments may be conducted in-person or online.
Anal Cancer Management and Treatment
This illustration shows the diameters of different tumors measured in centimeters next to common food items for comparison.
Anal cancer stages can be described using a scale from stage 0 to stage IV. A higher stage number indicates a more advanced cancer. Three factors are used to help determine the cancer stage: the size of the tumor, whether the cancer has spread to nearby lymph nodes, and whether the cancer has spread to distant lymph nodes or organs. The stage of a cancer helps determine its severity as well as how to treat it.
Stages of Anal Cancer
Stage 0 (carcinoma in situ) — This is the earliest anal cancer stage; abnormal cells are only found in the mucosa (innermost layer) of the anus.
Stage I (also called stage 1) — Tumors are 2 centimeters or smaller. Cancer has not spread to nearby lymph nodes.
Stage II(also called stage 2) — This stage is divided into stages IIA and IIB.
In stage IIA, the tumor is larger than two centimeters but not larger than five centimeters. Cancer has not spread to nearby lymph nodes.
In stage IIB, the tumor is larger than five centimeters and cancer has spread to lymph nodes near the rectum, but not to distant parts of the body.
Stage III (also called stage 3) — This stage is divided into stages IIIA, IIIB, and IIIC.
In stage IIIA, the tumor is five centimeters or smaller. Cancer may have spread to lymph nodes near the rectum, but not to distant parts of the body.
In stage IIIB, the tumor is any size and has spread to nearby organs, such as the vagina, urethra, or bladder. Cancer has not spread to nearby lymph nodes.
In stage IIIC, the tumor is any size and may have spread to nearby organs. Cancer has spread to lymph nodes near the anus or groin.
Stage IV(also called stage 4) — In stage 4, the cancer can be any size and may or may not have grown into nearby organs. Cancer may or may not have spread to nearby lymph nodes. The cancer has likely spread to distant organs, such as the liver or lungs, and is also known as metastatic.
Our Multidisciplinary Team Approach
Dana-Farber’s Gastrointestinal (GI) Cancer Treatment Center uses a multidisciplinary approach to care for patients diagnosed with anal cancer. Our expert team of medical, radiation, and surgical sub-specialists works together to determine your best course of treatment. Since anal cancer is a rare form of cancer, it is especially important to be seen by experts who have experience treating it and managing the treatment’s potential side effects.
Common treatment options for anal cancer may include:
Radiation therapy
Chemotherapy
The standard care for anal cancer that has not metastasized to another organ is radiation therapy and chemotherapy. Radiation is directed to the tumor itself and the lymph nodes around the groin (if appropriate), five days a week for six weeks. Chemotherapy is given intravenously in the first and fifth weeks of radiation. Some cancer treatment centers use chemotherapy pills rather than intravenous (IV) chemotherapy. Chemotherapy generally consists of two drugs:
5-fluorouracil (5-FU): This is the main chemotherapy drug used for anal cancer. In some cases, capecitabine may be used instead.
Mitomycin C: Determining the proper dosage of mitomycin C requires expert knowledge. Our medical oncologists are highly skilled in medication management. In special situations, cisplatin may be prescribed instead of mitomycin C.
Researchers at Dana-Farber are exploring new approaches to anal cancer treatment, including using immune therapy for early-stage disease and reducing the radiation dose for patients with small anal tumors.
After chemotherapy and radiation are completed, scans and exams will be done to check if the cancer has responded to treatment. Most patients with localized anal cancer — meaning cancer that hasn’t spread to lymph nodes or other organs — can be cured with chemotherapy and radiation.
Advanced Anal Cancer Treatment
Sometimes, anal cancer can reoccur after treatment. For anal cancer that returns to the anus or isn't eliminated by chemotherapy and radiation, surgery may be an option to remove the recurrent disease.
For patients who have metastatic anal cancer, initial treatment usually involves chemotherapy. In some cases, radiation and immunotherapy may be recommended. Patients with metastatic disease may also consider participating in a clinical trial as part of their treatment plan.
Our Center also conducts important research on anal cancer and runs clinical trials to develop promising new treatments. Research involving HPV-positive cancers — which help with the treatment of anal cancer — is a current focus area.
The first signs of cancer of the anus can be subtle and are often similar to symptoms of more common, non-cancerous conditions. Early symptoms may include:
Bleeding from the anus
One or more small lumps around the anus
Itching, pain, or a feeling of pressure near the anus
Changes in bowel habits, such as new or worsening diarrhea, constipation, or a change in how often you have bowel movements
These symptoms can also be caused by benign issues like hemorrhoids, anal fissures, or anal warts. However, if you notice anal bleeding, a new lump on or near the anus, or any of the symptoms above that persist or worsen, it’s important to see a healthcare provider right away. Early evaluation can help detect anal cancer at a more treatable stage.
No, lumps around the anus don't always signify anal cancer. Anal lumps can also be caused by benign (non-cancerous) conditions such as hemorrhoids, anal fissures, or anal warts.
Nevertheless, a new lump, a small hard lump, or a persistent hard nodule on or near the anus should be evaluated by a healthcare provider to rule out anal cancer or other serious conditions.
Most anal squamous cell cancers (the most common type of anal cancer) are caused by infection with human papillomavirus (HPV). HPV is a very common virus that infects the skin and mucous membranes, including the anus.
Other factors, such as a weakened immune system, smoking, and certain prior cancers, can also increase risk.
Yes, the HPV vaccine is a key tool in preventing HPV-related cancers, including anal cancer, as well as cervical, vaginal, vulvar, penile, mouth, and throat cancers. It is recommended for children starting at age 9 and for adults up to age 45.
Many patients with localized anal cancer — meaning cancer that has not spread to distant organs — can be cured with chemotherapy and radiation. Surgery can also be helpful for some patients. Outcomes depend on the stage of the cancer, the patient's overall health, and how well the cancer responds to treatment.
We offer a wide range of support programs and resources for patients, caregivers, and loved ones. Our supportive services are designed to help you navigate your care experiences with greater comfort and ease.
