Anal Squamous Cell Carcinoma
A cancer of the anal canal lining, most often linked to HPV
Quick Facts
- Type: Cancer of the anal canal
- Main link: Human papillomavirus (HPV)
- Common symptom: Anal bleeding, lump, or pain
- Outlook: Often treatable, especially when found early
Overview
Anal squamous cell carcinoma is a cancer that starts in the squamous cells, the flat cells that line most of the anal canal. It is the most common type of anal cancer. Because its symptoms overlap with common, harmless conditions such as hemorrhoids, it is sometimes mistaken for them at first.
Most cases are linked to long-term infection with certain high-risk types of human papillomavirus (HPV), the same virus group involved in cervical and some other cancers. When found early, anal cancer is often highly treatable, frequently without the need for major surgery.
Symptoms
Symptoms can be subtle and easy to dismiss. They may include:
- Bleeding from the anus or rectum
- A lump or mass near or in the anal opening
- Pain, pressure, or discomfort around the anus
- Itching in the anal area
- A change in bowel habits or the shape of stools
- Discharge from the anus
- Swollen lymph nodes in the groin
Because these symptoms often resemble hemorrhoids or anal fissures, it is important to have persistent or unexplained anal symptoms checked by a doctor rather than assuming they are harmless.
Causes
Most anal squamous cell carcinomas are linked to persistent infection with high-risk types of HPV, which can cause changes in the cells lining the anus that may slowly progress to cancer over time.
The cancer develops when these cells acquire genetic changes that let them grow uncontrollably. While HPV is the leading factor, not everyone with HPV develops anal cancer, and other factors influence the risk. HPV is very common and usually clears on its own without causing harm. Only persistent infection with certain high-risk types is linked to the slow cell changes that can eventually become cancer. A weakened immune system makes it harder for the body to clear the virus, which is one reason it raises the risk.
Risk Factors
- Persistent infection with high-risk HPV types
- A history of cervical, vulvar, or vaginal precancer or cancer
- A weakened immune system, including from HIV or immune-suppressing medication
- Receptive anal intercourse
- Smoking
- Older age
Diagnosis
Diagnosis involves examining the area and confirming the cancer with a tissue sample.
- Physical exam: a digital rectal exam and inspection of the anal area
- Anoscopy: using a short scope to look closely at the anal canal
- Biopsy: removing a small tissue sample to examine under a microscope, which confirms the diagnosis
- Imaging: CT, MRI, or PET scans to determine the size of the tumor and whether it has spread
People at higher risk may be offered screening tests, such as anal Pap tests, to detect precancerous changes early.
Treatment
Treatment depends on the size and stage of the cancer. Many anal cancers respond well to combined therapy.
- Combined chemotherapy and radiation: often the main treatment, this combination can cure many anal cancers while preserving normal bowel function
- Surgery: small, early tumors may be removed surgically; more extensive surgery is reserved for cancers that do not respond to other treatment or that come back
- Additional therapies: for advanced disease, treatments such as immunotherapy may be used
The treatment plan is tailored by a specialist team, and follow-up care is important to watch for recurrence.
Prevention
- HPV vaccination, which protects against the high-risk virus types most often linked to anal cancer
- Not smoking
- Practicing safer sex to reduce HPV exposure
- Screening for those at higher risk, such as people with HIV, when recommended
- Prompt evaluation of persistent anal symptoms rather than assuming they are harmless
- Limiting the number of sexual partners and using condoms to reduce HPV exposure
When to See a Doctor
See a doctor if you have anal bleeding, a lump, persistent pain, itching, or a change in bowel habits, especially if symptoms last more than a couple of weeks. Do not assume bleeding is only from hemorrhoids. Seek prompt care for:
- Anal bleeding that is new, persistent, or unexplained
- A growing lump or mass near the anus
- Ongoing anal pain or discharge
- Swollen lymph nodes in the groin
Early evaluation gives the best chance of finding and treating any problem while it is small.
Frequently Asked Questions
Is anal cancer caused by HPV?
Most anal squamous cell carcinomas are linked to persistent infection with high-risk types of HPV. Not everyone with HPV develops the cancer, but the virus is the leading risk factor, which is why HPV vaccination can help reduce risk.
How is anal cancer different from hemorrhoids?
Both can cause anal bleeding, lumps, and discomfort, which is why anal cancer is sometimes mistaken for hemorrhoids. The key difference is that cancer is confirmed by a biopsy. Persistent or unexplained anal symptoms should always be checked by a doctor.
Can anal squamous cell carcinoma be cured?
Yes, many cases are curable, especially when found early. Combined chemotherapy and radiation cures a large share of anal cancers while preserving normal bowel function, and surgery is reserved for select situations.
How can I lower my risk of anal cancer?
HPV vaccination, not smoking, and safer sex all reduce risk. People at higher risk, such as those living with HIV, may benefit from screening. Getting persistent anal symptoms evaluated promptly also helps catch problems early.
What are the first warning signs of anal cancer?
Common early signs include anal bleeding, a lump near the anus, pain or pressure, itching, and changes in bowel habits. Because these can seem minor, it is important not to ignore symptoms that persist.
References
- American Cancer Society. Anal Cancer.
- National Cancer Institute (NCI). Anal Cancer Treatment.
- MedlinePlus, U.S. National Library of Medicine. Anal cancer.
- Centers for Disease Control and Prevention (CDC). HPV and Cancer.