WASHINGTON -- Up to 6.6 million cigarette smokers will live substantially longer if cigarette smoking is replaced by vaping over a ten-year period, calculates a research team led by investigators from Georgetown Lombardi Cancer Center. In all, cigarette smokers who switch to e-cigarettes could live 86.7 million more years with policies that encourage cigarette smokers to switch completely to e-cigarettes.

Published in the journal Tobacco Control, the first study to model public health outcomes if cigarette smoking was replaced by e-cigarettes "supports a policy strategy that encourages replacing cigarette smoking with vaping to yield substantial life year gains," says the study's lead author David Levy, PhD, professor of oncology at Georgetown Lombardi.

For the study, Levy and a team of 10 investigators looked at such variables as harm from e-cigarettes, and amount of youth uptake, and the rate of cessation among others.

Two projections, one described as optimistic and one pessimistic, were made based on different scenarios regarding the relative harms of e-cigarettes compared to cigarettes as well as differences in the timing of smoking initiation, cessation and switching. Both scenarios conclude there still would be considerable premature deaths averted, but also a much larger number of life years saved.

The "pessimistic" scenario finds 1.6 million of these former cigarette smokers will have a combined 20.8 million more years of life, while the "optimistic" scenario calculates 6.6 million nicotine users who switch from cigarettes to e-cigarettes will live 86.7 more life years.

"In addition, there would be tremendous health benefits including reduced disease disability to smokers, reduced pain and suffering, and reduced exposure to second hand smoke," Levy says. "Even the gloomiest analysis shows a significant gain in years of life if nicotine is obtained from vaping instead of much more deadly amount of toxicants inhaled with cigarette smoke."

Levy says the findings might help the Surgeon General and the public health community find a solution to their call to end cigarette smoking.

"The 2014 U.S. Surgeon General Report recommended an endgame strategy for the country's tobacco epidemic, but no additional strategy was laid out other than the current status quo tobacco control policies," he says.

Those policies include higher cigarette taxes, smoke-free public places, media campaigns, cessation treatment programs and advertising restrictions.

"While those policies have been effective over time -- smoking prevalence has decreased markedly over the past 50 years -- their impact has been relatively slow," Levy says.

He points out that the most current and substantial research on the use of vaping shows that use of e-cigarettes can effectively help smokers give up cigarettes.

"Old policies need to be supplemented with policies that encourage substituting e-cigarettes for the far more deadly cigarettes," Levy says. "Together, these policies as well as regulating the content of cigarettes have the potential to drastically reduce the massive harms from smoking cigarettes."

Levy adds, "FDA Commissioner [Scott] Gottlieb recently outlined a strategy of reducing the nicotine content in cigarettes and a harm reduction approach to e-cigarettes. These approaches are right on track. While we know less about nicotine reduction than the other more traditional policies, the evidence to date indicates that this approach also holds promise, especially if smokers are encouraged to switch to e-cigarettes."

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The National Institutes of Health funded the study, which involved scientists from multiple universities and research groups. No industry funds were used. The models used in the study were developed by Levy and co-authors Rafael Meza, PhD, from the University of Michigan and Theodore R. Holford, PhD, from Yale University.

Study co-authors also include Zhe Yuan, MS, Yuying Luo, MS, and David B. Abrams, PhD, from Georgetown Lombardi Comprehensive Cancer Center (Abrams also has appointments at Truth Initiative and at New York University College of Global Public Health); Eric N. Lindblom, JD, from Georgetown University Law Center; Ron Borland, PhD, from Australia Cancer Control, Victoria, Australia; Richard J. O. O'Connor, PhD, and Maciej L. Goniewicz, PharmD, PhD, from Roswell Park Cancer Institute in Buffalo, New York; and Raymond Niaura, PhD, from the Schroeder Institute for Tobacco Research and Policy Studies at Truth Initiative. Goniewicz has received a research grant from Pfizer and served as an advisory board member to Johnson & Johnson, manufacturers of smoking cessation medications.

The study was funded by grants from the National Institute of Drug Abuse (R01DA036497), the National Cancer Institute's Cancer Intervention and Surveillance Modeling Network (UO1-CA97450), and the National Cancer Institute (PO1-CA200512).

About Georgetown Lombardi Comprehensive Cancer Center

Georgetown Lombardi Comprehensive Cancer Center is designated by the National Cancer Institute as a comprehensive cancer center -- the only cancer center of its kind in the Washington, D.C. area. A part of Georgetown University Medical Center and MedStar Georgetown University Hospital, Georgetown Lombardi seeks to improve the diagnosis, treatment, and prevention of cancer through innovative basic and clinical research, patient care, community education and outreach, and the training of cancer specialists of the future. Connect with Georgetown Lombardi on Facebook (Facebook.com/GeorgetownLombardi) and Twitter (@LombardiCancer). About Georgetown University Medical Center

Georgetown University Medical Center (GUMC) is an internationally recognized academic medical center with a three-part mission of research, teaching and patient care (through MedStar Health). GUMC's mission is carried out with a strong emphasis on public service and a dedication to the Catholic, Jesuit principle of cura personalis -- or "care of the whole person." The Medical Center includes the School of Medicine and the School of Nursing & Health Studies, both nationally ranked; Georgetown Lombardi Comprehensive Cancer Center, designated as a comprehensive cancer center by the National Cancer Institute; and the Biomedical Graduate Research Organization, which accounts for the majority of externally funded research at GUMC including a Clinical and Translational Science Award from the National Institutes of Health. Connect with GUMC on Facebook (Facebook.com/GUMCUpdate) and Twitter (@gumedcenter).