Dr. Engels and his colleagues have also analyzed the annual number of cancers in the HIV-infected population in the United States, both with and without AIDS. The researchers used large cancer registries for their analysis and found that during 1991-2005, an estimated 79,656 cancers occurred in the AIDS population. During that same period, non-AIDS defining cancers increased by approximately three-fold (P<0.001).6 The study revealed an increased incidence of lung cancer, anal cancer, liver cancer, and Hodgkin lymphoma.
The investigators also observed that the cancer burden was compounded by the rising proportion of individuals with AIDS over age 40 years, noting that the incidence of most cancers increases with age. This has left clinicians wondering if drug therapies may be a reason behind the increase in cancer rates among this population. There has always been a concern that long-term effects of HAART may be putting some individuals at higher risk for cancer. Dr. Casper feels differently. “There is no proof of that. Using the drugs early and aggressively have been shown to lower mortality so significantly, that even if there is a slight increase in risk in cancer, the risks are far outweighed by the benefits,” said Dr. Casper.
Studies also support those sentiments. However, investigators are now beginning to look at individual medications and their potential long-term carcinogenic properties. Powles and colleagues investigated the effects of HAART on the incidence of non-AIDS-defining cancers with a cohort of 11,112 HIV-positive individuals.7 The researchers had 71,687 patient-years of follow-up. They found that while there was no increased incidence in the pre-HAART era (1993-1995), incidence increased in the early HAART period (1996-2001) and remained elevated (2002-2007). Their multivariate analysis showed that the use of HAART (HR = 1.64; 95% CI, 1.13 to 2.39) and a nadir CD4 count less than 200/µL (HR=1.67; 95% CI, 1.10 to 2.54) were associated with an increased cancer risk. The investigators also found that only the non-nucleoside reverse transcriptase inhibitors (NNRTIs) (HR= 1.45; 95% CI, 1.01 to 2.08) were associated with a significantly increased risk of non-AIDS-defining cancers.
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4) Silverberg M, Chao C, Leyden W, et al. Cancer stage, age at diagnosis, and survival comparing HIV+ and HIV- individuals with common non-AIDS-defining cancers. Presented at 19th Conference on Retroviruses and Opportunistic Infections (CROI 2012), Seattle, Washington; March 8, 2012.
5) Engels EA, Brock MV, Chen J, et al. Elevated incidence of lung cancer among HIV-infected individuals. J Clin Oncol. 2006;24(9):1383-1388.
6) 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):753-762.
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