About Anal Cancer
Anal cancer is a cancer starting in the anus. Cancer is when the cells of the body begin to grow out of control. More than 90% of anal cancers are squamous cell cancers which mean these arise from the cells lining the anal canal.
The next most common type of anal cancer is adenocarcinoma which usually arises from the cells lining the rectum but can also arise from the glands in the anal canal. The rarest type of anal cancer is melanoma.
Anal cancer in NZ
Anal cancer is rare, however it’s becoming more common in New Zealand. In 2020, the most recent year reported, 107 people were diagnosed with anal cancer here, compared to 72 people in 2012, and 48 people in 2005*. Women are slightly more likely to develop anal cancer than men, and the average age at diagnosis is 60. In 2020 27 people died from anal cancer.
*NZ Cancer Registry
Symptoms
Most people with anal cancer experience bleeding, itching, or a lump around their anus, and may have some discomfort. The challenge with anal cancer is that the symptoms are often attributed to haemorrhoids. More than half of people with anal diagnosis are initially misdiagnosed as just having haemorrhoids, leading to a delayed diagnosis. It is important to see a doctor when experiencing any of these symptoms, and to follow up if symptoms don’t disappear with initial treatment.
HPV and anal cancer
The majority of anal cancers are caused by the Human Papilloma Virus (HPV). This is a very common virus - most people who have had sex have been exposed to HPV, but their immune systems will clear the virus. There are more than 150 different subtypes of HPV - HPV 16 and 18 are the two subtypes most commonly linked with anal cancer.
People with lowered immunity are less able to clear HPV, and therefore more likely to get anal cancer. Reasons for a lowered immune system include HIV infection, autoimmune conditions, or taking immune-suppressing medication after an organ transplant.
Smoking may also lower the ability of the body to clear HPV. People who smoke are more likely to get all HPV-associated cancers which include head and neck cancers, vaginal, vulval and penile cancers.
Why the HPV Vaccine is so important.
Where can I get more information about Anal Cancer?
These websites provide helpful and reliable information about anal cancer.