Anal cancer is an uncommon type of cancer that develops in the tissues of the anus or anal canal, the short passage at the end of the rectum through which stool leaves the body. Most anal cancers are squamous cell carcinomas, which develop from the thin, flat cells lining the anal canal. Other, less common types include adenocarcinoma, basal cell carcinoma, and melanoma. Anal cancer is strongly associated with infection by human papillomavirus (HPV), a very common virus that can cause changes in cells and, in some cases, lead to cancer over many years. However, having HPV does not mean that a person will develop anal cancer. Early anal cancer may cause few or no noticeable symptoms. When symptoms occur, they can sometimes resemble those of hemorrhoids, anal fissures, or other less serious conditions. Therefore, persistent or unusual symptoms should be evaluated by a healthcare professional.
Possible signs and symptoms of anal cancer include:
A lump, mass, or growth in or around the anus
Bleeding from the anus or rectum
Anal itching
Pain, discomfort, or pressure around the anus
Changes in bowel habits
Narrow or thin stools
A feeling of fullness or the need to have a bowel movement even after passing stool
Mucus or discharge from the anus
Difficulty controlling bowel movements
Swollen lymph nodes in the groin
Unexplained weight loss in some cases
Anal bleeding should not automatically be assumed to be caused by hemorrhoids. If bleeding, pain, a lump, or changes in bowel habits persist, medical evaluation is important.
The most important known cause and risk factor for many cases of anal cancer is infection with high-risk types of human papillomavirus (HPV).
HPV is a sexually transmitted infection that can spread through intimate skin-to-skin or sexual contact. In most people, the immune system clears HPV naturally. Persistent infection with certain high-risk HPV types can cause abnormal changes in cells that may eventually become cancerous. Anal cancer can also develop in people without a known history of HPV infection. In addition, cancer from another part of the body can occasionally spread to the anal region. Such a cancer is considered metastatic disease rather than a primary anal cancer.
A doctor may begin by asking about symptoms, medical history, medications, and risk factors. A physical examination may include an inspection of the area around the anus and a digital rectal examination, in which the doctor gently examines the anal canal and rectum with a gloved finger. Further tests may include:
A biopsy is usually necessary to confirm whether abnormal tissue is cancerous. During a biopsy, a small sample of tissue is removed and examined under a microscope by a pathologist.
Staging describes how large the cancer is and whether it has spread to nearby lymph nodes or other parts of the body. In general, anal cancer may be described as:
Early-stage cancer: Limited to the anal region.
Locally advanced cancer: Larger or involving nearby tissues or lymph nodes.
Metastatic cancer: Has spread to distant organs.
Accurate staging helps doctors determine the most appropriate treatment.
Treatment depends on the cancer’s type and stage, the location and size of the tumor, the person’s overall health, and other individual factors. For many patients with anal squamous cell carcinoma, the main treatment is a combination of radiation therapy and chemotherapy, often called chemoradiation. Treatment options may include:
Chemotherapy and radiation therapy are often given together because they can work more effectively in combination. This approach can control the cancer while helping many patients avoid major surgery.
Radiation therapy uses high-energy radiation to destroy cancer cells. A radiation oncologist plans and administers treatment according to the location and extent of the tumor.
Chemotherapy uses medicines that destroy cancer cells or prevent them from multiplying. It may be combined with radiation or used in other circumstances depending on the stage and type of cancer.
For some advanced or recurrent anal cancers, doctors may consider immunotherapy or other systemic treatments. The choice depends on the cancer’s characteristics and previous treatments.
Surgery is not always the first treatment for anal cancer. It may be considered for certain small tumors, cancers that return after initial treatment, or cancers that do not respond adequately to chemoradiation. Major surgery may occasionally be required for persistent or recurrent disease.
HPV vaccination can protect against HPV types associated with several cancers, including anal cancer. Vaccination is most effective when given before exposure to HPV, although recommendations vary according to age and individual circumstances.
Smoking is associated with an increased risk of several cancers, including anal cancer. Avoiding tobacco can reduce cancer risk and improve overall health.
Using barrier protection and reducing exposure to sexually transmitted infections can lower the risk of HPV transmission, although condoms and other barriers do not provide complete protection against HPV because the virus can infect skin that is not covered.
Depending on the symptoms and diagnosis, you may be referred to one or more of the following specialists:
Gastroenterologist: Evaluates diseases of the digestive tract and may perform procedures such as anoscopy or endoscopic examinations.
Colorectal Surgeon / General Surgeon: Evaluates anal and rectal conditions and performs biopsies or surgery when required.
Medical Oncologist: Diagnoses and manages cancer treatment, including chemotherapy and immunotherapy.
Radiation Oncologist: Plans and provides radiation therapy.
Pathologist: Examines biopsy tissue to determine whether cancer is present and identify its type.
Gynecologic Oncologist or Urologic Specialist: May be involved when the disease affects nearby reproductive or urinary structures, depending on the patient.
The outlook for a person with anal cancer depends on several factors, including:
The stage of the cancer at diagnosis
Tumor size
Whether nearby lymph nodes are involved
Whether the cancer has spread to distant organs
The type and characteristics of the tumor
Response to treatment
Overall health
Anal cancer is often treatable, particularly when it is detected before it has spread extensively. Modern treatments have allowed many patients to achieve long-term control of the disease.
No. Anal cancer begins in the anus or anal canal, while rectal cancer begins in the rectum. They are different diseases and may require different treatment approaches.
Many cases of anal cancer are associated with persistent infection with high-risk HPV types. However, HPV infection does not mean that a person will develop anal cancer.
No. Hemorrhoids, anal fissures, infections, inflammatory conditions, and other problems can also cause anal bleeding. However, unexplained or persistent bleeding should be evaluated by a healthcare professional.
Anal cancer can often be successfully treated, especially when diagnosed at an earlier stage. Treatment outcomes vary depending on the stage and other individual factors.
HPV vaccination can help prevent infection with HPV types associated with anal cancer and can therefore reduce the risk of HPV-related cancers. It does not eliminate all risk of anal cancer.
No. Cancer itself is not contagious. However, HPV, which is associated with many cases of anal cancer, can be transmitted through intimate or sexual contact.
Yes. Anal cancer can recur after treatment. Follow-up appointments are important because they allow doctors to monitor for recurrence and manage any treatment-related problems.
Medical Disclaimer: This article is intended for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. If you have persistent anal bleeding, a lump, pain, changes in bowel habits, or any other concerning symptoms, consult a qualified healthcare professional. Do not delay medical care based on information presented in this article.
