Cancer Is a Growing Concern Among People with HIV

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People with HIV continue to experience higher rates of both AIDS-defining and non-AIDS cancers in the era of effective antiretroviral therapy (ART), according to a report in the February 20, 2014, issue of AIDS. Increased longevity alone does not explain the rise in non-AIDS cancer rates, and further research is needed on the causes and best treatments for cancer in this population, the study authors concluded.

The incidence of AIDS-defining cancers -- that is, Kaposi sarcoma, primary central nervous system lymphoma, non-Hodgkin lymphoma, and cervical cancer -- have declined dramatically, by more than 70%, since the advent of effective combination ART, but HIV positive people still have higher rates than the general population, Paul Rubinstein from Rush University Medical Center in Chicago and colleagues wrote.

While survival of newly infected people with HIV "now rivals that of the general population," morbidity and mortality associated with non-AIDS-defining cancers such as lung cancer, liver cancer, anal cancer, and melanoma skin cancer "are significant and also continue to rise." In industrialized countries the number of cases of non-AIDS cancers now equals or exceeds those of AIDS-defining cancers.

Anal cancer is caused by the same human papillomavirus (HPV) strains as cervical cancer, and some experts believe it should also be considered AIDS-related. Liver disease, often due to chronic hepatitis B or C, is a growing cause of morbidity and mortality among people with HIV in the ART era, and these viruses can cause liver cancer.

Although increased longevity due to effective HIV treatment is the greatest risk factor for non-AIDS cancers, "[a]ge and immune status, however, are insufficient to fully explain these trends in cancer risk," according to the authors. The risk of some malignancies is higher in HIV positive people even when their CD4 T-cell count is normal. People with HIV also "present with more aggressive and advanced disease at the time of cancer diagnosis."

Standard incidence ratios, or degree of excess risk, for most non-AIDS cancers range from 2 to 35 for people with HIV. The most important risk factors for non-AIDS malignancies are advancing age and duration of HIV infection. The effect of CD4 count is less clear, and varies across different cancer types. Traditional risk factors such as smoking -- which some studies find to be more common among people with HIV -- also play a role. Even after controlling for smoking, however, HIV positive people have a higher rate of lung cancer compared with HIV negative people.

ART has been associated with reduced cancer incidence due to improvement of immune system function, but it may also reduce inflammation and excessive immune activation, which can contribute to a host of chronic age-related conditions including cardiovascular disease and cancer.

The effects of both non-AIDS and AIDS-defining cancer are "profound," and around 30% of people with HIV will die from these malignancies, according to the authors. More than 4000 new cases of cancer are diagnosed among HIV positive people in the U.S. each year.

"Developing robust strategies to screen this group for preventable cancers will become increasingly important," they wrote. "Unfortunately, standard guidelines for cancer screening in this group do not exist...Current epidemiological and etiological data strongly suggest that HIV/AIDS patients should be under increased surveillance not only for [AIDS-defining cancers], but likewise for [non-AIDS-defining cancers], even years earlier than the general population."

"The paucity in basic science, translational, and clinical research toward an understanding of the cause and best course of treatment for malignancies in HIV/AIDS raises the need for further investment of time, effort, and funds in these fields," they continued. "Enrolling patients into clinical trials who are diagnosed with HIV/AIDS is of utmost importance, as without structured research protocols, questions regarding treatment, pharmacology, cause, and screening will be more difficult to answer."

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Reference

PG Rubenstein, DM Aboulafia, and A Zloza. Malignancies in HIV/AIDS: from epidemiology to therapeutic challenges. AIDS 28(4):453-465. February 20, 2014.