A study has raised doubts about the potential benefits of e-cigarettes for helping cancer patients quit Getty

Cancer patients who smoke e-cigarettes were more nicotine dependent and equally or less likely to quit smoking traditional cigarettes than non-users, a new study has found.

Published early online in Cancer, a peer-reviewed journal of the American Cancer Society, the findings raise doubts about the potential benefits of e-cigarettes for helping cancer patients give up smoking.

Because of the risks of persistent smoking, all cancer patients who smoke should be advised to quit. But the rising use of e-cigarettes has raised many questions among patients and their health care providers including whether e-cigarette use helps or hinders quitting efforts.

To study the link between e-cigarette use and cessation among cancer patients, researchers at the Memorial Sloan Kettering Cancer Center in New York City studied 1074 cancer patients who smoked.

The participants were enrolled in a tobacco treatment program within a comprehensive cancer center between 2012 and 2013.

The researchers observed a three-fold increase in e-cigarette use between these years, of 10.6% versus 38.5%. At enrollment, e-cigarette users were more nicotine dependent than non-users, had more prior quit attempts, and were more likely to be diagnosed with lung or head and neck cancers.

At follow-up, e-cigarette users were just as likely as non-users to be smoking. Seven day abstinence rates were 44.4% versus 43.1% for e-cigarette users and non-users, respectively.

"Consistent with recent observations of increased e-cigarette use in the general population, our findings illustrate that e-cigarette use among tobacco-dependent cancer patients has increased within the past two years," said Dr Jamie Ostroff, who led the research.

She stressed that the study had several limitations, and additional studies are required: "Controlled research is needed to evaluate the potential harms and benefits of e-cigarettes as a potential cessation approach for cancer patients."

"In the meantime, oncologists should advise all smokers to quit smoking traditional combustible cigarettes, encourage use of FDA-approved cessation medications, refer patients for smoking cessation counselling, and provide education about the potential risks and lack of known benefits of long-term e-cigarette use."

Peter Hajek, director of the Tobacco Dependence Research Unit at Queen Mary, University of London, told Reuters that the study contained flaws.

"The authors followed up smokers who tried e-cigarettes but did not stop smoking, and excluded smokers who tried e-cigarettes and stopped smoking," he said.

"Like smokers who fail with any method, these were highly dependent smokers who found quitting difficult. The authors concluded that e-cigarette use was not helpful, but that would be true for any treatment however effective if only treatment failures were evaluated."

There are estimated to be around 1.3 million e-cigarette users in the UK and sales have soared in the past two years. Despite this, the health benefits of smoking e-cigarettes, battery-powered vapourisers which stimulate tobacco smoking by producing an aerosol, are contested.

In the US, the Food and Rugs Administration in April proposed the first set of e-cigarette rules in an attempt to curb their use.