Anal Cancer – What Is It, Am I at Risk and Should I Be Screened?
Anal cancer is uncommon, but rates are increasing in certain groups, and early detection can make a significant difference.
This article explains what anal cancer is, who may be at higher risk, common symptoms to watch for, and when screening may be recommended.
What is anal cancer?
Anal cancer refers to cancers that arise from the skin surrounding the anus and the lining of the anal canal. It differs from bowel and rectal cancer, which originates from cells lining the bowel. While anal cancer can be aggressive, early detection significantly improves outcomes. Treatment typically involves radiation therapy which can be quite nasty, with major surgery as a last resort. However, if caught early, small tumours can often be managed with surgical removal alone.
What are the symptoms of anal cancer?
Symptoms of anal cancer may include:
A lump or mass in or near the anus
Rectal bleeding or blood in the stool
Persistent pain or discomfort in the anal region
A significant change (pain, bleeding, inability) with bottoming
Unexplained itching or irritation
Changes in bowel habits, such as diarrhea, constipation or narrower stools
Unusual discharge from the anus
If you experience any of these symptoms, it's important to consult your doctor for a thorough evaluation.
Should I be concerned about anal cancer?
Anal cancer isn’t common, but its incidence is rising in Western countries like Australia—especially among high-risk groups, including people living with HIV (PLWHIV) and men who have sex with men (MSM). In fact, the risk of anal cancer in some of these groups can exceed that of bowel cancer. See below for other risk factors. Screening is essential, as it allows for the detection and treatment of precancerous changes before they progress to cancer. Early/small cancers can also be detected and potentially treated with less invasive procedures, leading to better outcomes.
What causes anal cancer, and how does HPV relate to it?
Most anal cancers are linked to high-risk human papillomavirus (HPV) infections. Whilst HPV rarely comes up in conversation, it is incredibly common and spreads through skin-to-skin contact, including sexual activity. The good news is that while most people will encounter the virus at some point in their lives, their immune system will overcome it without any issues. Those with a weakened immune system though, might not be so lucky.
Other strains of HPV can cause genital warts, which are generally benign but may indicate a heightened risk for anal cancer. It is common to have been exposed to multiple different strains of HPV.
In Australia, children (all genders) have routinely been vaccinated since 2013, significantly reducing their risk of various cancers, including anal cancer. While the benefits of vaccinating sexually active adults (who have likely already been exposed to HPV) are less certain, many healthcare providers believe it’s still beneficial and, at the very least, poses minimal harm. Adults can also receive the vaccine, but may have to pay for it. It is advisable to discuss HPV vaccination with your doctor or HRA specialist.
How do I know if I’m at risk for anal cancer?
Factors that increase your risk of anal cancer include:
HIV Status: Living with HIV, especially for MSM.
Sexual History: MSM, trans women, and multiple sexual partners, due to increased exposure to HPV.
Previous anal warts or pre-cancer (‘HSIL’ or ‘AIN’)
Age: Increased risk after age 50.
Other genital cancers: History of vulvar, vaginal, or cervical cancers or pre-cancer.
Smoking: Tobacco use.
Should I be screened for anal cancer?
The 2022 ANCHOR study provided strong evidence that diagnosing and treating anal pre-cancer significantly reduces the risk of developing anal cancer. Following this, the International Anal Neoplasia Society (IANS), the leading body on all things anal neoplasia, published guidelines outlining who should be screened and how. These groups include:
People Living with HIV (PLWHIV)
Men who have Sex with Men (MSM) and trans women
Individuals with a history of vulvar cancer or pre-cancer
Solid organ transplant recipients
These guidelines have been adapted locally by ASHM (Australian Sexual Health Medicine), recommending that MSM and trans women living with HIV over 35, and all others living with HIV over 45, should be screened.
What does anal cancer screening involve?
The screening process typically involves:
Digital Anorectal Examination (DARE): This involves inspecting and palpating (feeling) inside the anal canal, as cancers can often be felt.
Anal Swabs: Swabs are taken from inside your anus (the same as when testing for STIs), looking for the presence of high-risk HPV and/or abnormal cells of the anal canal. If initial tests show abnormal results, you should be referred for high-resolution anoscopy (HRA), which is crucial for identifying and subsequently treating HSIL (high-grade squamous intra-epithelial lesions which is the medical term for pre-cancer).
If HSIL has been found for other reasons, such as incidentally on a haemorrhoid, you should be referred directly for an HRA.
HRA is a specialised procedure that allows for a magnified view of the anal canal to identify suspicious-looking areas suggestive of HSIL. Once confirmed with a biopsy, these can be treated using HRA.
Because HRA is a highly specialised procedure, there are not many doctors trained to perform it, especially in Melbourne. This makes access to a trained provider difficult. Dr Marino has tailored his colorectal training to provide HRA in Melbourne, ensuring patients have access to this vital screening service.
For more detailed information about HRA and what to expect, please refer to Dr Marino’s dedicated blog on HRA.
What should I do if I have concerns about developing anal cancer?
If you think you have a reason to pursue anal cancer screening, have concerns or wish to know more, it is best to discuss this with your doctor. They may conduct an initial assessment and refer you for HRA if needed, or they may directly refer you to a specialist trained in anal cancer screening. It's always good to ask questions and take an active role in your health.
Dr Marino is an LGBTQIA+ friendly colorectal and general surgeon based in Melbourne, specialising in anal cancer screening and high-resolution anoscopy (HRA). If you’re concerned about your risk or wish to pursue screening, please consult your GP for a referral to Dr Marino.
