Lung Cancer Declining in People With HIV, but Still High

Lung cancer rates declined for people living with HIV but remained higher than the general population and, in older individuals, even higher than other cancers normally considered to be associated with HIV/AIDS, a population-based registry linkage study showed.

The overall outlook for lung cancer improved for HIV-positive people during the study period from 2001-2016, decreasing by 6% per year overall. Comparing 2001-2004 with 2013-2016, the age-standardized incidence rate fell from 124.4 to 58.3 per 100,000 person-years.

That shift brought the standardized incidence ratio down, but it still remained 48% higher versus the general population in 2013-2016, Cameron Haas, MD, of the NIH in Rockville, Maryland, and colleagues reported in the Lancet HIV.

HIV-positive status "should be considered for inclusion in the entry criteria for lung cancer screening programs," wrote Adam Januszewski, MBBS, PhD, of St. Bartholomew's Hospital in London, and Mark Bower, MD, PhD, of Chelsea and Westminster Hospital in London, in an accompanying commentary.

Compared with cancers that are normally associated with HIV/AIDS, the 5-year cumulative rate of lung cancer for people living with HIV ages 50-59 pulled even with Hodgkin lymphoma and Kaposi sarcoma as of 2011. For HIV-positive patients ages 60-69, the 5-year cumulative rate of lung cancer exceeded that of Hodgkin lymphoma and Kaposi sarcoma (1.36% vs 0.45% and 0.12%).

"For the increasing proportion of people living with HIV who are living beyond the age of 50 years, the absolute risk of lung cancer has surpassed that of common AIDS-defining cancers and is a considerable excess risk and public health burden," the researchers wrote, pointing out that the over-65 population with HIV will double in 2030. "Strategies for prevention and early detection are necessary to reduce the disparities in lung cancer risk for people living with HIV."

Some of the increased burden of lung cancer in HIV positive people could be "plausibly explained by confounding due to smoking prevalence" in this population, Haas and colleagues explained. A quarter of the general population smokes, compared with 40% of HIV-positive people 70 and older.

While a high percentage of lung cancers are also attributed to smoking in the general population, HIV status may be another predictor on its own.

Lower CD4/CD8 counts also contribute to higher rates of lung cancer, "which are suggestive of T-lymphocyte replicative senescence and exhaustion; this association supports the hypothesis that immune dysfunction might contribute to carcinogenesis," Januszewski and Bower wrote. They also pointed to a small study out of Uganda in which most of the 18 cases of HIV-positive lung cancer were non-smokers with CD4 counts of more than 200 cells/µL, "which suggests that an unknown factor was contributing to lung carcinogenesis."

The researchers saw less lung cancer in the younger HIV-positive population and more decline in rates, including an 11% drop per year from 2001-2016 in the 20-29 age group.

In 20- to 39-year-olds living with HIV, the 5-year cumulative incidence of lung cancer in 2011-2016 was 0.02% (95% CI 0.01-0.03). Incidence climbed with every decade of life: 0.22% for age 40-49, 0.62% for age 50-59, and 1.36% for age 60-69, as noted. At age 70 and older, the rate was 1.65%.

Lung cancer rates were highest in people living with HIV who inject drugs, specifically in women (2013-2016 standardized incidence ratio 3.27, 95% CI 2.45-4.28).

Researchers examined data from over 4 million people in the U.S. living with HIV over a period of 16 years through the HIV/AIDS Cancer Match study, which links data from HIV and cancer registries in the U.S. In total, there were 3,426 lung cancer diagnoses.

To compare the HIV positive population to the general population, investigators used standardized incidence ratios calculated by dividing the observed number of lung cancer diagnoses in people living with HIV by the expected number, estimated by applying general population cancer incidence rates to person-time in the HIV population based on sex, attained age, race and ethnic group, calendar year, and registry.

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