The highest risk of lung cancer were seen in HIV patients who were smokers or former smokers (adjusted IRR; 4.06 (95% CI; 2.66 - 6.21), male patients with heterosexual route of HIV infection (adjusted IRR; 4.19 (95% CI; 2.20 - 7.96)) and HIV patients with prior AIDS defining events or low baseline CD4 cell count (adjusted IRR; 3.25 (95% CI; 2.01 - 5.24)). Here, CD4 is linked to AIDS.