We're seeing an increase in anal cancer cases among US men, and HIV may be the culprit, according to a study published in the Journal of the National Cancer Institute.
I was surprised to learn that the estimated number of anal cancer cases in 2012 was just over 6,000; I thought this number would be higher with the number of cases our clinic used to see. But unfortunately, this number has been steadily increasing in the general population since 1940 and even more so since 1980, as more of the population became infected with HIV.
The rise in HIV cases is strongly associated with the rise in anal cancer cases; anal cancer is the fourth most common cancer found in HIV-infected people. However, it remains unclear how anal cancer cases among people with HIV has affected anal cancer incidence in the general population.
In order to answer this question, researchers from the National Cancer Institute looked at data from the HIV/AIDS Cancer Match Study. They analyzed more than 20,000 anal cancer cases including those with and without HIV between 1980 and 2005 in several US states.
NCI researchers found that of these 20,000 cases, an estimated 1,665 individuals were infected with HIV. Between 2001 and 2005, 1.2 percent of women with anal cancer and 28.4 percent with anal cancer were HIV-positive. It appears that between 1980 and 2005, the increasing rate of anal cancer cases among women infected with HIV was significantly less than the men identified in this study, suggesting that a large portion of males with anal cancer in recent years were HIV-positive.
The study authors conclude by stating that measures that would effectively prevent anal cancer in HIV-infected males could markedly reduce anal cancer rates at the population level. I have to agree with their statement, but I also have to wonder: Where does HPV come into all of this?
The rise in HPV-related cancers seems to be an area of interest to cancer researchers these days, and there’s a reason for that. We already know that HPV causes cervical and head and neck cancers, but HPV is associated with anal cancers as well.
When comparing anal cancer cases in men that are HIV-positive being higher than women, HPV-related anal cancer cases are actually higher among women, especially Caucasian women.
With the development of vaccines for HPV, we can only hope that the HPV-related cancer incidence will decrease, but with the number of HIV and HPV-infected individuals out there, I fear that we will continue to see an increase in the number of anal cancer cases, not a decrease.
Have you noticed an increase in the number of anal cancer cases at your cancer center? If so, how many of these cases are thought to be related to HIV or HPV?