Background:  Lung cancer incidence is elevated among HIV⁺ individuals, who frequently smoke. Incidence may be increasing as persons live longer on HAART and as they age. It remains unclear whether immune suppression is related to lung cancer risk in this population.

Methods:  Lung cancer cases were identified through surgical and pathology department records and linked to a cohort of 5242 HIV⁺ individuals followed at Johns Hopkins Hospital in Baltimore (1989 to 2003). Negative binomial regression was used to assess associations between lung cancer incidence and various demographic and clinical characteristics. Expected counts of lung cancer, specific for age, sex, race, and calendar year, were calculated using data from all U.S. SEER registries (representative of the U.S. population) and specifically from Detroit (a similar urban area). Standardized incidence ratios were then calculated to measure relative risk vs the general population.

Results:  We observed 37 lung cancers (incidence 194/100,000 person-years). Histologically, cases were classified as adeno- (n = 21), squamous cell (8), other non-small cell (6), or small cell (2) carcinomas. Incidence increased over time (per 100,000 person-years:  56 in 1989–1994, 203 in 1995–1999, 250 in 2000–2003; p trend = 0.03), and climbed steeply with age (40 for < 40 years, 302 for 40 to 49 years, 560 for ≥ 50 years; p trend < 0.001). Incidence did not vary by sex or race, and was similar across strata defined by recent CD4 count (p trend = 0.74), nadir CD4 count (0.23), and recent HIV viral load (0.52). Overall, lung cancer incidence was markedly elevated compared to the general U.S. population (standardized incidence ratios were 7.7, 95% CI 5.5 to 11) and to urban Detroit (5.2, 95% CI 3.7 to 7.2). Compared with Detroit, relative risk tended to increase over calendar time in parallel with incidence rates (1.7 in 1989–1994, 5.9 in 1995–1999, 5.9 in 2000–2003; p trend = 0.17), but actually decreased with age (8.7 for < 40 years, 8.1 for 40 to 49 years, 3.0 for ≥ 50 years; p trend = 0.005).

Conclusions:  Lung cancer, especially adenocarcinoma, is common among HIV⁺ persons in urban Baltimore and increasing in incidence, identifying it as a malignancy of public health importance. Although lung cancer affects mostly older HIV⁺ adults, incidence in younger HIV⁺ persons is markedly increased compared to the general population. We did not find evidence that immune suppression was related to risk, suggesting that an especially high prevalence of heavy tobacco use or another co-factor is important.

Keywords: lung cancer; tobacco; epidemiology