In late 2010, results from a Canadian study showed that using HRA, or high resolution anoscopy, is the most cost-effective way to screen for anal cancer. With HRA, a doctor uses a small camera called an anoscope to look at and take a tissue sample from the anus to later screen for cancerous cells.
HIV-positive people in general have higher rates of abnormal cells of the anus (called dysplasia) and anal cancer than HIV-negative people. This is due to infection with HPV, or the human papillomavirus. As well, HIV-positive men who have sex with men (MSM) have much higher rates of anal cancer ... up to 160 times higher. Although standard procedures are not in place for screening anal dysplasia and cancer, many experts believe yearly screening is wise in HIV-positive MSM, and perhaps all people living with HIV.
The study compared the accuracy, cost and ability to distinguish high-grade anal dysplasia between HRA and the two other, less expensive screening methods: the HPV genotype test and the anal Pap smear (swabbing the anus for tissue). Just over 400 HIV-positive MSM were screened in three groups (of whom HRA results were already available): one with HRA only, one with HRA only after a Pap smear showed cancer-causing strains, and one with all three screenings.
The results found 98 cases of grades 2/3 dysplasia and showed HRA was better able to detect these cases than Pap smear or Pap smear + HPV genotype. Many cases of grades 2/3 were missed by the Pap smears, and sometimes the cost of several Pap smears with HPV tests was eventually more costly than HRA only.
HRA may not be available to everyone who wishes to be screened in this way. Additionally, the procedure requires more training than the other two methods, which may make it difficult for some to make this screening method a part of their routine HIV care.