The more than 4 in 10 people living with HIV in the United States hooked on cigarettes face dire prospects of dying of lung cancer.

Researchers used computer simulation models to estimate the risk of lung cancer among the U.S. population living with the virus. They projected that 25 percent of people with HIV who smoke and adhere to their antiretrovirals (ARVs) will die of lung cancer, a figure that rises closer to 30 percent for heavy smokers. Among those smokers who quit when they are 40 years old, only a projected 6 percent will die of the malignancy. Depending on how many cigarettes they smoke per day and their sex, smokers who are adherent to their HIV meds are an estimated six to 13 times more likely to die of lung cancer than of AIDS-related complications. Among smokers who adhere poorly to their ARVs, an estimated 15 percent will die of lung cancer.

The researchers also estimated that of all those currently in care for HIV in the United States, about 1 in 10, or nearly 60,000, will die of lung cancer, including both those who do and do not smoke.

“Smoking is now a greater threat to the health of people with HIV on treatment than the virus itself,” says Krishna Reddy, MD, a pulmonologist and critical care physician at Massachusetts General Hospital and the study’s lead author. “The good news is that quitting smoking can help people breathe better and live longer.”