IAS: Incidence of some cancers increasing significantly in HIV-positive individuals

Several non-AIDS-defining cancers occur more frequently in people with HIV than in the general population, according to data from two large US cohorts presented as a poster to the recent International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention in Sydney.

The study also revealed that although the incidence of the AIDS-defining cancers, Kaposi’s sarcoma and non-Hodgkin’s lymphoma has declined significantly since the introduction of effective HIV treatment, the incidence of five non-AIDS-defining malignancies, including anal cancer, has increased significantly.

The investigators note that some of these non-AIDS-defining cancers are preventable, and also call for the evaluation of screening programmes designed to detect pre-cancerous anal lesions.

The findings echo those of a large meta-analysis published last month in The Lancet, which showed an elevated risk of various cancers in both HIV-positive people and those immunosuppressed after organ transplants.

Potent anti-HIV therapy had lead to a significant improvement in the prognosis of HIV-infected individuals. Indeed, many doctors are now optimistic that with timely and appropriate anti-HIV therapy, many HIV-positive individuals will be able to live a more or less normal lifespan.

But HIV-positive individuals continue to become unwell. This is partly because antiretroviral drugs can cause long-term side-effects such as lipid disturbances and bone problems. Furthermore, some studies have suggested that several non-AIDS-defining cancers, such as anal cancer, skin cancer, Hodgkin’s lymphoma, and lung cancer are more likely to occur in HIV-positive patients than the general population.

Therefore, investigators wished to establish the incidence of the cancers seen most often in HIV-positive individuals in the USA relative to the general US population between 1992 and 2003. They also wished to determine the trends of cancers amongst people with HIV in three time periods: 1992 – 1995 (when potent anti-HIV therapy was unavailable); 1996 – 1999 (the early years of effective antiretroviral therapy); 2000 – 2003 (an era of improved anti-HIV therapy and treatment strategies).

A retrospective study was designed by the investigators. Information on HIV-positive patients was drawn from two large observational cohorts: the Adult/Adolescent Spectrum of Disease (ASD) Project, and the HIV Outpatient Study (HOPS). The incidence of cancer amongst HIV-positive individuals enrolled in these cohorts was compared to that observed amongst the general US population in the Surveillance and End Results (SEER) Project.

Data from over 54,000 HIV-positive individuals, who contributed over 157,000 person years of follow-up, were available for analysis. A total of 3,427 incident cancers were recorded in the ASC/HOPS cohorts. The overwhelming majority of these (2,842, 83%) were the AIDS-defining cancers cervical cancer, Kaposi’s sarcoma and non-Hodgkin’s lymphoma.

Unsurprisingly, the incidence of AIDS-defining cancers was significantly higher in HIV-positive individuals than the general US population. But the investigators also noticed that seven non-AIDS-defining cancers were also significantly more likely to be diagnosed in individuals with HIV than in the general US population. These cancers were: anal cancer (standardised incidence rate [SIR]: 42.9); Hodgkin’s lymphoma (SIR: 14.7); liver cancer (SIR: 7.7); lung cancer (SIR: 3.3); melanoma (SIR: 2.6); oropharyngeal cancer (SIR: 2.6); and, colorectal cancer (SIR: 2.3). Of the nine most commonly observed cancers in the USA, only prostate cancer and breast cancer did not occur more frequently in people with HIV than the general US population.

The investigators then looked at trends over time of cancer rates in people with HIV. The incidence of Kaposi’s sarcoma fell significantly (p

But the investigators established that the incidence of several non-AIDS-defining cancers increased significantly in HIV-positive individuals after HIV treatment first became available, and continued to increase after 2000. These cancers were anal cancer (p

“Our findings indicate that HIV-infected persons are at higher risk than the general population of developing many cancers, including several non-AIDS-defining cancers” comment the investigators. They suggest that this is because “prolonged exposure to viral ocogenes, moderate immune suppression, and genomic instability could result in impaired cancer surveillance and the subsequent development of tumors in these patients.”

The incidence of some of these cancers could, the investigators suggest, be reduced if doctors advised their patients against smoking and undertook routine screening for cervical and colorectal cancer. They also recommend that the value of screening for pre-cancerous anal lesions should be studied.