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HIV Infection Increases Risk for Lung Cancer Mortality Independent of Smoking
Gregory D Kirk*1, C Merlo1, P O'Driscoll1, S Mehta1, D Vlahov2, and J Samet1
1Johns Hopkins Univ, Baltimore, MD, US and 2New York Academy of Med, NY, US
Background: HIV+ persons have an elevated risk
of lung cancer, due in part to a high prevalence of smoking. Prior studies are
limited by the inability to directly control for smoking.
Methods: Since 1988, the ALIVE
Study has prospectively followed a cohort of injection drug users (IDUs) in Baltimore, MD
with semi-annual collection of clinical, laboratory and behavioral data. Clinical
diagnoses are confirmed through medical record abstraction. Lung cancer deaths
were identified through linkage with the National Death Index. Cox proportional
hazards regression was used to examine the effect of HIV infection on lung
cancer death, while controlling for other covariates including smoking (average packs / day) and drug use variables.
Results: Among 2,960 ALIVE participants followed for ~22,000 person-years, we
identified 27 individuals that died from lung cancer; 14 were HIV+ and 13 HIV-.
Although not statistically significant, lung cancer death rates were increased in
the post-HAART (after 7/1/96) compared
to pre-HAART era (RR 1.98, 95% CI: 0.83-5.22).
HIV+ cases were slightly younger than HIV-‘s (51 vs. 55
yrs, p=0.06) but had similar gender, racial, smoking and drug
use patterns. Smoking and age >50 were strongly associated with lung cancer mortality.
After adjusting for age, gender and smoking, HIV+’s
had a 3.04 increased hazard for lung cancer death compared to HIV-‘s (1.39-6.65). Further, recurrent pneumonia (2 or > hospitalizations) was associated with lung
cancer death (RH 1.99; 1.10-9.20) and
explained some of the HIV effect (RH reduced to 2.34;
1.01-5.43). Neither injection nor inhaled drug use were
associated with lung cancer mortality. Among HIV+ lung cancer deaths, the
median CD4 nadir was 208 cells/μl
and HIV RNA maximum level was 133,000 copies/ml; only 5 of 14 had ever received
HAART. Smoking and age >50 remained the primary risk factors in analysis of HIV+’s only; CD4 count, viral load and HAART use were not
associated with lung cancer mortality.
Conclusions: With
prolonged survival of HIV+ persons in the post-HAART era, lung cancer deaths are
increasing. After controlling for the high prevalence of smoking, HIV infection
remained a significant risk factor for dying from lung cancer. Increased lung
cancer risk following recurrent pneumonia may explain some but not all of this
association. Although the sample size is small, lung cancer mortality among HIV+’s was not associated with
history of advanced immune suppression nor with HAART use.
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