Study: More than 60% of adult e-cigarette users in the U.S want to quit More than 60% of U.S. adults who vape are interested in quitting, according to a study published today in JAMA Network Open by MUSC Hollings Cancer Center researchers. And among those who vape to help them to quit smoking, some are successful while others continue smoking and using electronic cigarettes. The study, which analyzed longitudinal survey data from more than 30,000 adults across the country, aimed to provide the most up-to-date estimate of how many Americans are interested in stopping their use of e-cigarettes or have made past attempts to quit.