Reuters Health Information: REFILE-Long-term HIV viral suppression tied to lower cancer risk
REFILE-Long-term HIV viral suppression tied to lower cancer risk
Last Updated: 2018-06-26
(In para 6, corrects definition of early suppression.)
By Marilynn Larkin
NEW YORK (Reuters Health) - Long-term viral suppression reduced the risk of both AIDS-defining and non-AIDs-defining cancers in HIV-positive veterans, although they were still at greater risk for cancer than uninfected individuals, researchers say.
"Increasingly, we are recognizing that many cancers are driven by viruses," Dr. Leslie Park of the Stanford Center for Population Health Sciences told Reuters Health by email. "Understanding how HIV interacts with viral coinfections and results in higher risks of cancer may offer critical insight in how we might better prevent and treat these cancers for everyone."
Dr. Park and colleagues compared cancer rates for 42,441 HIV-positive veterans and 104,712 matched but uninfected veterans from 1999-2015. Median followup was 7.4 years for HIV-positive individuals and 10.1 years for those who were not infected.
Cancer types were categorized as: all cancer; AIDS-defining cancers (ADCs; i.e., Kaposi sarcoma, non-Hodgkin lymphoma, and invasive cervical cancer); non-AIDS-defining cancers (NADC) caused by oncogenic viruses (e.g., non-Hodgkin and Hodgkin lymphoma associated with Epstein-Barr virus; human-papillomavirus-related cervical, anal or genital cancer; hepatoma related to hepatitis B or C virus); nonvirus NADC; and poorly specified cancer.
Viral suppression was defined as an HIV RNA level less than 500 copies/mL.
For each HIV-positive person, each day of observation was classified as unsuppressed, early suppression (from the initial period up to two years of continuous suppressed time), or long-term suppression (continuous suppression after two years).
"In examining different cutpoints for early-suppression," Dr. Park noted, "we found that achieving at least one year of suppression resulted in similar trends as our primary analysis, which used the cut point of two years."
As reported online June 11 in Annals of Internal Medicine, cancer incidence for HIV-positive versus uninfected individuals was highest for unsuppressed persons (relative risk, 2.35); lower for those with early suppression (RR, 1.99); and lowest among those with long-term suppression (RR, 1.52).
This trend was strongest for ADC (unsuppressed: RR, 22.73; early suppression: RR, 9.48; and long-term suppression: RR, 2.22). The trend was much weaker for NADC caused by viruses (unsuppressed: RR, 3.82; early suppression: RR, 3.42); and long-term suppression: RR, 3.17), but showed a benefit for cancer of the lung and larynx, as well as melanoma and leukemia, according to Dr. Park.
No risk differences were seen for NADC not caused by viruses.
"Our findings suggest that early, sustained antiretroviral therapy, which results in long-term viral suppression, may contribute to cancer prevention," the authors state. "However, excess cancer risk remained among patients with long-term suppression."
"We did not investigate longer durations of long-term suppression (e.g., five or 10 years)," Dr. Park said, "and we believe the findings in our study warrant a full exploration of the precise timing in a future investigation."
"Our investigation took into consideration major known cancer risk factors, such as sex, race/ethnicity, smoking, alcohol use disorder/dependence, hepatitis C infection and diabetes as potential confounders," she added. However, "we did not examine differences in cancer risk among patients with the different risk factors or comorbidities. This is definitely of interest for future research."
Dr. Gina Mantia-Smaldone of Fox Chase Cancer Center in Philadelphia, said in an email to Reuters Health, "Clinicians should educate HIV-positive patients on the importance of early initiation and long-term compliance with antiretroviral therapy . . . and that their risk for cancer is still higher than uninfected individuals, thus emphasizing the importance of continued cancer screening."
Ann Intern Med 2018.