The rate of anal cancer among men who have sex with men (MSM) living with HIV in Switzerland peaked in 2009 and could decline even further if more of this population is treated with antiretrovirals (ARVs) and cancer screening rates rise, aidsmap reports.

Publishing their findings in the journal AIDS, researchers from the Swiss HIV Cohort Study created a mathematical model that charted the rate of anal cancer starting in 1980 and, according to projections, forward through 2030. They factored in rates of HIV treatment, trends in CD4 levels and rates of screening for precancerous lesions. They relied on the medical records of 6,411 MSM in care for HIV between 1983 and 2015 to guide their projections.

The median lowest-ever CD4 count, known as a nadir, rose from 229 in the period spanning 1980 to 1989 to 394 between 2010 and 2015. By 2010 to 2015, 83 percent of the group was on ARVs.

The researchers estimated that the rate of anal cancer among the group peaked in 2009 at 0.082 percent per year. This decline leveled off between 2010 and 2015.

The study authors projected that if the rate of ARV use remains stable, the anal cancer rate will decline to 0.059 percent per year in 2030, a 28 percent reduction since 2009. If 100 percent of the group were treated for HIV from 2016 going forward, the 2030 cancer rate would decline to 0.052 percent per year, an 11 percent reduction compared with the rate should the current ARV treatment rate persist.

If all HIV-positive MSM were treated with ARVs and received an annual anoscopy to detect signs of anal cancer as well as treatment if necessary, the anal cancer rate would decline 44 percent compared with maintaining current trends, to 0.033 percent per year.

To read the aidsmap article, click here.

To read the study abstract, click here.