Anal cancer is a disease of the anal canal, the latter approximately 3 centimetres of the digestive tract, and the anal margin, the area of perianal skin approximately 5 centimetres out from the anal opening. Like cervical cancer, anal cancer is predominantly caused by infection by cancer-causing types of the human papillomavirus (HPV). Indeed, after cervical cancer, anal cancer is the most common HPV-caused cancer, affecting over 300 Australians per year. Anal cancer typically arises in persons between 30 and 50 years old, though all sexually-active persons are at risk.
Anal cancer is very responsive to nonsurgical therapy utilising chemotherapy and radiation when detected in early stages; however internal manifestations of disease and an often asymptomatic presentation mean many patients present when the cancer is more advanced, making for more invasive treatment and worse clinical outcomes. Anal cancer has a complex distribution, with certain populations having greater risk of disease than others, including persons living with HIV, persons with a recent diagnosis of cancer and smokers. However a recent study in Tasmania found much lower than expected proportions of these risk groups among Tasmanian anal cancer patients, suggesting disease in Tasmania and other rural areas may be distinct from urban populations.
Among the population groups at greater risk of disease, there is a notable difference by sex, as women have consistently higher frequencies of disease than men. The reason for this higher frequency of disease in women is uncertain, and is being investigated in TasGANS. Also, while persons living with HIV typically have greater frequencies of HPV-caused cancers, in Tasmania rates are unexpectedly low. This population is thus being investigated in the Tas+HPV study.
This disease is being researched in the following projects: