Q&A: ‘Concerning rise’ in anal cancer underscores need for effective screening programs
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Despite being considered a fairly rare disease, the incidence of anal cancer has doubled over the last 30 years, with the American Cancer Society estimating approximately 10,540 new cases and 2,190 related deaths in 2024.
“It is the 25th most common cancer in U.S. and about 10,000 new cases are diagnosed each year,” Syed Husain, MD, MBBS, colorectal surgeon at The Ohio State University Comprehensive Cancer Center and Arthur G. James Cancer Hospital and Solove Research Institute, told Healio. “While being rare, anal cancer is on the rise and its incidence has doubled over last 30 years. This concerning rise in incidence underscores the need for effective screening programs for this cancer.”
Anal Cancer Awareness Day is March 21, and although it occurs during Colorectal Cancer Awareness Month, key differences distinguish anal cancer from rectal and colon cancers, including causes and known risk factors.
Healio spoke with Husain to learn more about the differences between anal cancer and CRC, screening methods for those at risk, and signs and symptoms patients should be aware of.
Healio: What is anal cancer and how does it differ from CRC?
Husain: Anal cancer affects the very end of our intestine, which is really the external anal opening and anal canal which extends 2 to 3 inches just inside the opening into the rectum. It is different from colon cancer in the sense that it is a cancer the originates in the skin.
The anus is covered by normal skin, which extends just inside the rectum before we start seeing the inner lining of the intestine or mucosa. Colon and rectal cancers originate from the mucosa whereas anal cancer originates from the skin itself. In that sense, it behaves very differently compared with colon or rectal cancers.
Healio: How do people develop anal cancer?
Husain: Almost all cases of anal cancer can be attributed to HPV infection in that area. HPV is a very common virus, and about 70% of the population is exposed at some point in life. Exposure can occur in many ways, though most contract HPV through sexual contact.
For some reason, a subset of patients are not able to clear the virus, and it lingers in that area. It is a slow process, usually taking many years, but it eventually becomes anal cancer.
Healio: As we know, CRC is highly preventable and curable if caught early. Can we say the same for anal cancer?
Husain: It is exactly the same for anal cancer — we have very effective methods of screening and preventing anal cancer.
What’s interesting is that over the past 30 years, the number of CRC has declined and that’s primarily because of screening. On the other hand, when we look at anal cancer, the numbers have doubled over the last 30 years and that is because of lack of screening.
There are very few centers that are offering effective screening for anal cancer. But if effective screening protocols are followed, the incidence of anal cancer can be reduced by up to 60%.
Healio: What are “effective screening protocols” and who should get screened?
Husain: It is easy to discern when to screen for colon cancer because the guidelines are clear: After age 45 everybody should get a colonoscopy. The reason behind universal screening for colon cancer is that the incidence of colon cancer is much higher than anal cancer.
On the other hand, anal cancer screening is not recommended for everyone, and there are certain high-risk populations we want to screen. This includes women who have a history of HPV, meaning their cervical pap smear comes back positive, or women who have a history of cancer or precancerous changes in the genital area.
Anal cancer and genital cancer among women are very closely linked; they are caused by the same type of viruses. It is very common for us to see that if the genital, vaginal, vulva or cervical areas are affected by HPV, those patients also have a very high incidence of anal involvement because of the close proximity.
Another group that should undergo screening are men who have sex with men, especially if they are HIV positive. Outside of these groups, patients who already have a history of anal HPV infection or precancerous cells are considered high risk and should get screened.
Fortunately, screening for anal cancer is a lot easier than screening for colon cancer. It is very simple and does not involve bowel prep for most patients. Screening includes a simple swab of the skin around the anus, which is sent for testing. If that anal pap smear comes back abnormal, we recommend further intervention but, for most high-risk patients, all they need is an annual anal pap smear.
Healio: How do signs and symptoms of anal cancer differ from CRC?
Husain: In most cases, CRC usually presents with bleeding and anemia. For anal cancer, the dominant symptom in most cases is pain in the anal area. Bleeding can also be seen with anal cancer, but pain is the dominant symptom that often distinguishes it from colon cancer. Many patients also notice a lump in the anal area.
The biggest problem with determining whether symptoms are due to anal cancer is the fact that a lot of these symptoms are also produced by hemorrhoids, which we know is a very common condition. What I usually tell my patients is that if the symptoms are transient — if you experience discomfort, pain and swelling that goes away within a week or so — then it is probably related to hemorrhoids. But, if you’re experiencing consistent or recurrent symptoms that last beyond 2 weeks, you need to see your doctor. This is especially the case if you belong to high-risk groups.
Healio: What else should our readers know about anal cancer?
Husain: The key message is high-risk populations need to have annual anal pap smears. Many providers are uncomfortable screening patients, as it is a sensitive area and many offices don’t have the equipment needed to do anal pap smears. But as long as providers are aware that these patients are at a higher risk for anal cancer, they can refer them to us or similar practices that are doing anal cancer screening. Many CRC surgery practices also have the ability to assist with referrals if they don’t provide the service themselves.
If you are still having trouble, the International Anal Neoplasia Society has online resources to help find a provider who can perform screenings.
Reference:
- Key statistics for anal cancer. https://www.cancer.org/cancer/types/anal-cancer/about/what-is-key-statistics.html. Accessed March 12, 2024.
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