HIV-Associated Cancers: A Paradigm Shift?
Many HIV-associated cancers develop with the help of oncoviruses — some of which are sexually transmitted.
Many HIV-associated cancers, including those labeled AIDS-defining cancers, develop with the help of oncoviruses — some, but not all of which, are sexually transmitted.
Kaposi sarcoma, for example, Dr Ambinder said, requires co-infection with Kaposi sarcoma–associated herpesvirus (KSHV), a virus in the herpes family discovered in 1994. Although KSHV is transmitted primarily through saliva between men who have sex with other men, why they constitute the highest risk group is not yet understood.6
“It's a bit like smoking,” Dr Ambinder said. “Many people smoke, but most smokers don't get lung cancer.”
“The issue is [that] after you take an individual with HIV infection and they are treated with antiretroviral medication and achieve suppression of the virus, are they totally healthy?” said Jeffrey Martin, MD, MPH, an epidemiologist and physician at the University of California, San Francisco School of Medicine. “We don't know the answer yet.”
What researchers do know, he said, is that when measuring particular biochemicals in the blood between HIV-infected individuals and those without this viral infection, “the HIV-infected persons have many more chemical abnormalities,” especially related to inflammation. HIV-infected people also have more oncoviruses, in general, than the HIV-free population, primarily those that are sexually transmitted. “If and how these chemical abnormalities translate into disease is what researchers are trying to understand.”
Even CD4 counts — a blood marker of immune strength, considered the strongest predictor of HIV progression — are a factor in some, but not all non-AIDS defining cancers, Dr Martin said. Although the more damage HIV does to these immune cells, the more likely a cancer is to develop, differences in risk are small, he said, and nothing like the decimation seen in the cancers that have long defined AIDS.
“It may be that a low CD 4 count six years ago may be the impetus for lung cancer development 6 years later,' he said, “whereas with Kaposi sarcoma, low CD4 numbers translate into KS within months.”
Surprisingly, perhaps, people living with HIV infections have not seen a rise, so far, in the incidence of the most common cancers: breast, prostate, and colon cancers.
Dr Martin suggested that the reason for this may be the biological differences between these and other cancers. “HIV is not a general stimulant for hundreds of different cancers,” he said.
Dr Yarchoan, however, suggested another reason. “My take is immunologic control may not be as important in these cancers' earlier development,” he said.
He added that less screening may be done in this group of patients than in the general population, because physicians are focusing on HIV and think of cancer as a distant threat. Yet with the improving life expectancy of patients with HIV, the hope is this should change — and change quickly.
- Yarchoan R, Uldrick TS. HIV-associated cancers and related diseases. N Engl J Med. 2018;378(11):1029-41. doi: 10.1056/NEJMra1615896
- Morlat P, Roussillon C, Henard S, et al. Causes of death among HIV-infected patients in France in 2010 (national survey): trends since 2000. AIDS. 2014;28(8):1181-91. doi: 10.1097/QAD.0000000000000222
- Suneja G, Lin CC, Simard EP, Han X, Engels EA, Jemal A. Disparities in cancer treatment among patients infected with the human immunodeficiency virus. Cancer. 2016;122(15):2399-407. doi: 10.1002/cncr.30052
- More people living with HIV and cancer should get appropriate cancer treatment, according to new guidelines [news release]. Fort Washington, PA: National Comprehensive Cancer Network; February 27, 2018. https://www.nccn.org/about/news/newsinfo.aspx?NewsID=1010. Accessed April 2018.
- Shiels MS, Pfeiffer RM, Gail MH, et al. Cancer burden in the HIV-infected population in the United States. J Natl Cancer Inst. 2011;103(9):753-62. doi: 10.1093/jnci/djr076
- Kaposi sarcoma: causes, risk factors, and prevention. American Cancer Society website. https://www.cancer.org/cancer/kaposi-sarcoma/causes-risks-prevention.html. Accessed April 2018.