Anal cancers attributed to human papillomavirus are more common in areas in Victoria, Australia, with higher HIV notifications.

BACKGROUND

Anal cancer is more common in men who have sex with men with HIV. We aimed to determine if there was an association between anal squamous cell carcinoma (SCC) and HIV notifications in men in Victoria, Australia, at a population level.

METHODS

We calculated the male age-standardised incidence rates for anal SCC, brain cancer and colon cancer for each local government area (LGA) in Victoria from 1982 to 31 December 2010 using the Victorian Cancer Registry. Male HIV rates in each LGA were calculated using the Victorian HIV Registry.

RESULTS

There were 288 men diagnosed with anal SCC, 8793 with brain cancer and 23?938 with colon cancer in 57 LGAs. There were 3163 men notified with HIV during the same period in the same LGAs (range: 4-435 per LGA). There was a significant positive correlation (r=0.45, P<0.001, r(2)=0.20) between the age-standardised rate of anal SCC and the rate of HIV notifications in men in each LGA but no correlation between the male age-standardised rate of colon (Pearson's r=-0.11, P=0.40) or brain (r=-0.05, P=0.71) cancers, and the rate of HIV. The rate of anal cancer was ~50% higher in LGAs with the highest HIV notification rate (incidence rate ratio=1.47; 95% confidence interval: 1.10-1.97).

CONCLUSIONS

At a population level, about one in five cases (r(2)=0.20) of anal SCCs in men are explained by the rate of HIV notifications in that LGA.