HIV Cancers in Resource-Limited Regions

Abstract

About 29 of 33 million persons living with human immunodeficiency virus (HIV) or the acquired immunodeficiency syndrome (AIDS) (PLHA) worldwide in 2009 reside in resource-limited countries. The burden of cancer in this population is substantial, although there is much we still do not know about the epidemiology of various HIV-associated tumors in these regions. Access to life-extending combination antiretroviral therapy (cART), which has been rapidly expanding since 2000, has improved survival to nearly normal life expectancy, including in resource-limited countries where about 30 % of PLHA are receiving cART. The improvements in survival with HIV, however, are occurring at the expense of increased incidence of chronic co-morbidities including cancer in PLHA on cART. Sparse data about risk of cancer in PLHA in resource-limited countries complicates efforts to evaluate this concern. Cancer is diagnosed in about 30 % of PLHA in developed countries. Cancers in PLHA are historically categorized as “AIDS-defining” cancer (ADC) or “non-AIDS-defining” cancers (NADC). ADCs include Kaposi sarcoma (KS), aggressive non-Hodgkin lymphoma (NHL), including Burkitt lymphoma (BL), and invasive cervical cancer. These cancers have a viral etiology and are more likely to be associated with degree or duration of immunosuppression. NADCs include Hodgkin lymphoma, anogenital, liver, and lung cancer. Most of these cancers have a viral etiology or are associated with lifestyle factors, e.g., cigarette smoking or injection drug use, which are more prevalent in PLHA. These cancers often occur in spite of sustained immune-restoration. Thus, NADCs have assumed greater importance as PLHA survive longer and ADCs proportionately decrease. Cancer is diagnosed in fewer than 5 % of PLHA in resource-limited countries. This rate is likely a gross underestimate, and is also affected by competing mortality from endemic infectious diseases such as malaria and tuberculosis. The low access to diagnostic services in low resource settings may also mean that a notable fraction of cancers remain undiagnosed in PLHA. Increasing access to affordable cART in resource-limited settings is likely to rapidly reduce infectious co-morbidities such as tuberculosis and thus amplify the importance of cancer in PLHA. Studies of PLHA in resource-limited countries are needed to characterize the additional cancer burden in PLHA to inform public health policy and knowledge about cancer etiology in different populations.