CD4 and AIDS: Nevertheless, other record linkage studies of cancer registries with cohorts of HIV-infected persons (Clifford et al, 2005) and/or AIDS registries (Chaturvedi et al, 2007; Polesel et al, 2010) have failed to observe any link between CD4+ cell counts and lung cancer risk, or any change in risk between the pre-combined antiretroviral therapy (cART) and cART era.