Johns Hopkins Hospital has a database of about 12,000 patients with lung cancer going back to 1950. In there, researchers found 80 HIV-positive lung cancers, which turned out to be by far the largest such population in any one place - a large enough group to begin studying.
The increased risk of lung cancer in people with HIV, Brock said, is three to five times that for the general population. The risk remains high, he said, even when controlled for smoking. The patients who are appearing at Hopkins, he said, have more late-stage lung cancer, appear to smoke less and are significantly younger than other lung cancer patients. The median age among HIV-positive lung cancer patients is 46; among others it is 64.
"These patients die and they die quickly," Brock said. The average time from HIV diagnosis to lung cancer diagnosis is six years, he said.
"The deaths here were overwhelmingly cancer-related," he said. "They were not due to AIDS."
Dr. Eric Engels, who is studying AIDS and lung cancer at the National Cancer Institute, said lung cancer has not been linked to a cancer-causing virus but wonders whether it might be caused by an unknown infection, scarring in the lungs or some sort of inflammation. If so, that could explain why it is developing more in those with HIV.
Engels said that learning more about how the immune system and cancer interact could have broader application than just helping people with HIV. "This research has implications for people who have a healthy immune system too," he said.
Dr. Robert Redfield, an associate director of the Institute of Human Virology, hypothesizes that some of the malignancies could be due to some of the drugs given over the years to people with HIV to keep them alive.
Wainberg said he worries that there are certain people at high risk for getting HIV who figure they don't have to be concerned about getting the virus because of the strides made in treatment.
"There is no doubt that there are people among vulnerable groups who now have a bit of an attitude of ... 'If I get HIV, the drugs are going to help me anyway,' " he said. They need to know, he said, about the cancer risks.
Engels said none of the talk of cancer risks should diminish the gains that have been made this decade in treating people with HIV in the United States. "If you had to pick a time and a place to live with HIV infection, America today would be the best time and place we've ever had," he said. "But we're finding these problems coming to the surface that we didn't see before."
