OAKLAND, Calif. — A large study with follow-up over 14 years offers a unique way of looking at the risk of cancer among HIV-positive individuals by accounting for the competing risk of death in the era of highly effective antiretroviral therapy (ART), as reported today in the Annals of Internal Medicine.
“This analysis provides easily interpretable information for HIV patients and their providers about their long-term cancer risk, and helps us identify where public health and clinical efforts should be focused to achieve the biggest impacts,” said co-author Richard D. Moore, MD, MHS, of the Johns Hopkins School of Medicine, and overall principal investigator of the North American Cohort Collaboration on Research and Design (NA-ACCORD).
“In the era before antiretroviral therapy, people who were infected with HIV were dying of AIDS. Now that use of this therapy is greatly increasing the lifespan of HIV-infected patients, their risk of developing other diseases, such as cancer, has increased,” said lead author Michael J. Silverberg, PhD, MPH, Research Scientist at the Kaiser Permanente Northern California Division of Research. “These patients have a higher burden of cancer compared with the general population due to impaired immune function and chronic inflammation, as well as a higher prevalence of risk factors including smoking and viral co-infections.”
The competing risk of death approach is not new, but this is one of the first times it has been applied to studies of cancer risk in HIV-infected patients. This approach provides estimates of the cumulative incidence of cancer by age 75 years, a measure that has not been reported previously in this population and may have clinical and public health utility since it approximates lifetime risk of cancer.
“Our approach allowed us to disentangle the effects of longevity from other factors on the risk of cancer,” explained Silverberg. “For example, we found that longevity was the main contribution to the increased risk over time for anal, colorectal and liver cancers. The risk for other cancers, such as lung cancer, melanoma and Hodgkin's lymphoma, did not appear to increase over time. This was because the increased risk with longevity was compensated for by other factors, such as decreases in smoking or adverse sun exposure behaviors.”
The study population consisted of 86,620 HIV-infected and 196,987 uninfected adults followed between 1996 and 2009 in 16 cohorts from the U.S. and Canada participating in the NA-ACCORD.
Researchers used the competing risk of death approach to estimate cumulative cancer incidence by HIV status and calendar era. Among HIV-infected subjects, the median CD4 count (a measure of the strength or weakness of the immune system) increased. Despite increasing age, the mortality rate decreased, but even in 2005-2009 the mortality rate was over three-fold higher than in uninfected subjects.
The researchers identified several clinical implications regarding cancer screening in HIV patients:
“As the HIV-infected population ages, future estimates of lifetime cancer risk could be stratified by levels of cancer risk factors,” said Silverberg. “Factors such as CD4 count, smoking, alcohol consumption, and HBV or HCV infection, could more accurately inform patients and providers about risk and further target prevention efforts.”
The study was funded primarily by grants from the National Institutes of Health.
Other authors of the study include Bryan Lau, PhD, MHS, Gregory D. Kirk, MD, PhD, MPH, Sharada P. Modur, PhD, Yuezhou Jing, MS, Keri N. Althoff, PhD, MPH, and Gypsyamber D’Souza, PhD, Department of Medicine, Johns Hopkins School of Medicine, and Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Md., USA; Chad J. Achenbach, MD, MPH, Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, Ill.; Eric A. Engels, MD, MPH, and James J. Goedert, MD, National Cancer Institute, National Institutes of Health, Bethesda, Md.; Nancy Hessol, MSPH, Department of Clinical Pharmacy, University of California, San Francisco; John T. Brooks, MD, and Pragna Patel, MD, MPH, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Ga.; Ann N. Burchell, PhD, MSc, Ontario HIV Treatment Network and Dalla Lana School of Public Health, University of Toronto; M. John Gill, MB ChB, MSc, Department of Medicine, University of Calgary; Robert Hogg, PhD, British Columbia Centre for Excellence in HIV/AIDS, Vancouver; Michael A. Horberg, MD, HIV/AIDS, Mid-Atlantic Permanente Research Institute, Kaiser Permanente, Rockville, Md.; Mari M. Kitahata, MD, MPH, Department of Medicine, University of Washington, Seattle, Wash.; Phillip T. Korthuis, MD, MPH, Department of Medicine, Oregon Health and Sciences University; William C. Mathews, MD, MSPH, Department of Medicine, University of California San Diego; Angel Mayor, MD, MSc, Retrovirus Research Center, Universidad Central del Caribe School of Medicine, Puerto Rico; Sonia Napravnik, PhD, Division of Infectious Diseases, School of Medicine, University of North Carolina; Richard M. Novak, MD, College of Medicine, University of Illinois at Chicago; Anita R. Rachlis, MD, MEd, FRCPC, Sunnybrook Health Sciences Centre, University of Toronto; Timothy R. Sterling, MD, Department of Medicine, Vanderbilt University, Nashville, Tenn.; James H. Willig, MD, MSPH, Division of Infectious Diseases, University of Alabama; Amy C. Justice, MD, MSc, PhD, and Robert Dubrow, MD, PhD, VA Connecticut Healthcare System and Yale University Schools of Medicine and Public Health; for the North American AIDS Cohort Collaboration on Research and Design (NA-ACCORD) of IeDEA.
About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes, and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and society at large. It seeks to understand the determinants of illness and well-being, and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 500-plus staff is working on more than 400 epidemiological and health services research projects. For more information, visit www.dor.kaiser.org or follow us @KPDOR.
About Kaiser Permanente
Kaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America’s leading health care providers and not-for-profit health plans. Founded in 1945, Kaiser Permanente has a mission to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve more than 10 million members in eight states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal physicians, specialists and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the-art care delivery and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education and the support of community health. For more information, go to: kp.org/share.