Lung cancer is more common among HIV-infected people than the general population. Recent data from a national study of women infected with the virus or at risk of infection point to smoking habits as the cause rather than the virus.
Researchers have known that the incidence of lung cancer among HIV-infected individuals is statistically higher than expected based on rates in the general population. While the reason for this increase is unknown, most studies have found that the virus may contribute.
The increase in lung cancer among HIV-infected women is not the result of HIV, but rather is due to smoking, according to recent data from the National Institutes of Health-sponsored Women’s Interagency HIV Study (WIHS), reported by Alexandra Levine, M.D., M.A.C.P., chief medical officer of City of Hope, in the March 20 issue of the Journal of Clinical Oncology.
Previous research has shown that lung cancer has grown significantly among HIV-infected women since modern antiviral drugs were introduced. To explore the potential link, Levine and a multi-institutional team of researchers compared the health records of a group of HIV-infected women to those of another group of HIV-uninfected women from WIHS.
The researchers analyzed lung cancer data among more than 2,650 HIV-positive women and nearly 900 comparable HIV-negative women who share the same lifestyle. All women have been examined every six months since 1993, with a full assessment of clinical, epidemiologic, immunologic and outcome data, Levine said.
The analyses showed that the HIV-infected women had a statistically higher risk of lung cancer than that of the general population. However, the HIV-negative women had the same increased lung cancer risk — and there was no difference between lung cancer incidence among the HIV-positive versus HIV-negative women.
Seeking to pinpoint the cause of increased lung cancer risk among women in WIHS, the researchers dug deeper and found another common trait among all of the women with lung cancer: cigarette smoking.
“Women in the study who had lung cancer, regardless of HIV status, smoked much more than in the study who did not get lung cancer, and also much more than women in general in the U.S.,” said Levine. None of the study participants who avoided smoking developed lung cancer.
Levine and her team found that two-thirds of the women enrolled in the WIHS study smoked, and all of those with lung cancer smoked. The finding suggested HIV-infected women and those at increased risk for infection may be more prone to smoking, putting them at increased lung cancer risk.
“Our results point to a strong need for programs that help HIV-infected women avoid or quit smoking,” Levine said.
The researchers also compared lung cancer incidence in HIV-positive women who took potent HIV-fighting drugs to lung cancer incidence among HIV-infected women diagnosed before these modern drugs were introduced. They found no difference between the rates, countering concerns that the drugs might contribute to lung cancer development.
Levine and the research team called for more study to further pin down the exact role, if any, that HIV plays in lung cancer development.