Several studies presented at the 2010 International AIDS Conference in Vienna, Austria, examined rates of cancer development in people with HIV. Additional studies looked at cancer risks in people taking Selzentry and the effectiveness of Isentress during chemotherapy.

Two of the studies focused on rates of cancers, particularly non-AIDS-defining cancers, in people with HIV and AIDS.

AIDS-defining cancers are cancers that are common in people with advanced HIV infections as a result of their weakened immune systems. Although they can appear in people who are HIV-negative, the development of these cancers in a person with HIV is closely tied to the health of the immune system. As a result, a person with HIV who has an AIDS-defining cancer is usually classified as having AIDS.

In contrast, developing a non-AIDS-defining cancer does not lead to a diagnosis of AIDS. Non-AIDS-defining cancers are in some cases more common in people with HIV than in the general population, but can occur even in people who carefully control their HIV infection.

Antiretroviral therapy has significantly improved the health and survival of people living with HIV. As a result, the rates of AIDS-defining cancers such as Kaposi’s sarcoma and non-Hodgkin’s lymphoma have decreased.

However, longer lifespans increase the risk for non-AIDS-defining cancers. As people with HIV survive longer with antiretroviral therapy, non-AIDS-defining cancers, which develop over a long time period, become more common.

In general, studies presented at AIDS 2010 found that the rate of non-AIDS-defining cancers among people with HIV and AIDS has increased rapidly, with HIV-positive individuals generally being diagnosed with such cancers at an earlier age than HIV-negative adults.

Two additional studies showed that Selzentry (maraviroc) is not associated with a higher risk of cancer and that switching to Isentress (raltegravir) during chemotherapy may allow cancer patients to safely receive full-dose chemotherapy.

Non-AIDS-Defining Cancers Are Increasing In People With AIDS

A study from the National Cancer Institute and the Centers for Disease Control (CDC) presented an estimation of the number of cancers over time in the U.S. AIDS population.

According to the study authors’ estimations, the number of AIDS-defining cancers decreased and the number of non-AIDS-defining cancers increased significantly among people with AIDS. Researchers attributed these changes to the growth and aging of the AIDS population and increased rates of certain cancers.

The researcher analyzed data from the CDC and cancer registries across the United States, and found that the share of adults aged 50 years or older increased from 8 percent of the population with AIDS in 1991 to 29 percent in 2005.

During the same period, AIDS-defining cancers, mainly Kaposi’s sarcoma and non-Hodgkin’s lymphoma, decreased 75 percent from 7,284 cases in 1993 to 1,736 cases in 2005.

In contrast, non-AIDS-defining cancers increased nearly six-fold from 416 cases in 1991 to 2,437 cases in 2005. Anal cancer and prostate cancer had the largest increases, with 20-fold and 12-fold increases in the number of cases, respectively.

Rates of lung cancer and Hodgkin’s lymphoma remained fairly stable.

The researchers also estimated that 4,388 cases of cancer occurred between 2004 and 2007 among people from 34 states who were HIV-positive but did not have AIDS. This included 892 cases of lung cancer, 381 cases of anal cancer, and 327 cases of Hodgkin’s lymphoma.

However, the researchers did not indicate if these numbers were increasing or decreasing over time.

The researchers emphasized that “cancer prevention and treatment in HIV-positive persons is increasingly important.”

People With HIV Get Non-AIDS-Defining Cancers Earlier And More Often

Another study examined the rate of cancer and age at cancer diagnosis in patients at an HIV clinic in Atlanta. Researchers found that many non-AIDS-defining cancers occurred at higher rates and at an earlier age in people with HIV compared to the general Atlanta population.

From 2000 to 2007, 512 clinic patients were diagnosed with cancer. Of these, 62.5 percent had AIDS-defining cancers and 37.5 percent had non-AIDS-defining cancers.

On average, the age of HIV-positive patients at cancer diagnosis was 42 years old. Except for Hodgkin’s lymphoma, all non-AIDS-defining cancers occurred earlier in the HIV-positive clinic population than in the general population.

Breast cancer occurred in the HIV-positive population an average of 7 years earlier than in the general Atlanta population. Liver cancer was diagnosed an average of 16 years earlier.

Additionally, cancer rates in people with HIV were much higher compared to the general Atlanta area population, except for prostate cancer and breast cancer. Lung cancer occurred 4.5 times more often than expected, after taking into account age, race, and gender; Hodgkin’s lymphoma occurred 20 times more often than expected, and anal/rectal cancer occurred 68 times more often.

The researchers reported that the clinic patients in general had fairly advanced HIV infections. Of those diagnosed with non-AIDS-defining cancers, average CD4 (white blood cell) counts were 263 cells per microliter for men and 344 cells per mcroliter for women.

Only 17 percent of the men and 11 percent of the women had undetectable viral loads (amount of virus in the blood) at the time of their cancer diagnosis.

The researchers did not determine whether the low CD4 counts and high viral loads played a role in the rate of cancer occurrence.

The scientists concluded that people with HIV should consider cancer screening earlier than the general population.

Selzentry Does Not Increase Cancer Risk

A study sponsored by Pfizer, the maker of Selzentry, reported the rate of cancer development for treatment-naïve and treatment-experienced clinical trial participants taking Selzentry. Results showed that participants in the Phase 2b/3 trials were not more likely to get cancer from taking Selzentry.

Selzentry belongs to a relatively new class of antiretrovirals called entry inhibitors. Entry inhibitors work by preventing HIV from entering and infecting human cells.

Although approved for use in treatment-experienced patients in 2007 by the U.S. Food and Drug Administration, there were concerns that Selzentry might cause cancer because of the unique way it works, which is different from other antiretroviral drugs.

To see if people taking Selzentry are actually at higher risk of developing cancer, researchers analyzed tumors reported in studies involving both treatment-experienced and treatment-naïve HIV-positive trial participants. A total of 1,499 patients were given Selzentry, 361 patients received Sustiva (efavirenz), and 270 received a placebo.

Cancer rates were similar for patients given Selzentry to rates for patients given Sustiva or the placebo. Rates of AIDS-defining cancers ranged from 0.6 percent to 1.6 percent of participants taking Selzentry, versus 0 percent to 2.4 percent of participants taking Sustiva or a placebo.

Rates of non-AIDS-defining cancers ranged from 0.8 percent to 3.6 percent for participants taking Selzentry, versus 1.6 percent to 2.5 percent for participants taking Sustiva or a placebo.

In all cases, these differences were not large enough to be significant.

Researchers also found that older age was associated with higher overall risk of tumor development in both treatment-experienced and treatment-naïve patients.

Isentress-Based HAART Is Safe And Effective During Chemotherapy

A small study investigated the safety and efficacy of Isentress-based HAART in HIV-positive patients treated for lymphoma with chemotherapy. Results showed that Isentress is effective in patients receiving chemotherapy and patients can receive full-dose chemotherapy while on Isentress.

In the past, doctors have worried about drug interactions between antiretrovirals and chemotherapy drugs. As a result, HIV-positive cancer patients often temporarily stop antiretroviral treatment while undergoing chemotherapy or take a reduced dose of chemotherapy drugs.

However, both of these adjustments can affect a patient’s health, either by allowing HIV to multiply again or by limiting the effectiveness of the chemotherapy.

Since Isentress is an integrase inhibitor, a relatively new class of antiretroviral drugs that work differently than most antiretrovirals, researchers thought Isentress may be safe even during chemotherapy.

To test this hypothesis, researchers examined nine patients treated for lymphoma with Isentress-based HAART and chemotherapy at the Centre hospitalier de l’Université de Montréal between May 2008 and December 2009.

Of the nine patients studied, seven had non-Hodgkin’s lymphoma and two had Burkitt’s lymphoma. Four patients were treatment-naïve, four patients had already achieved viral suppression with another antiretroviral regimen, and one patient had started antiretroviral treatment but still had a detectable viral load.

During chemotherapy and treatment with Isentress, eight of the nine patients achieved or maintained undetectable viral loads. Three months after chemotherapy, seven of the nine patients had survived (78 percent); two died due to progression of their lymphoma.

None of the patients developed antiretroviral treatment-related side effects during the chemotherapy.

The researchers concluded that Isentress can be used safely and effectively with full-dose chemotherapy for treatment of lymphoma.

For more information, please see the AIDS 2010 conference website.