E-cigarettes may not be effective in helping cancer patients quit smoking, according to a recent study.

Researchers found that cancer patients who use e-cigarettes are more nicotine dependent and less likely to quit smoking traditional cigarettes than those who didn't use e-cigarettes, KGNS News reported.

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. The findings raise doubts about the potential benefits of e-cigarettes for helping cancer patients give up smoking.

For the study, researchers collected data from more than 1,000 cancer patients who smoked and were enrolled between 2012 and 2013 in a tobacco treatment program within a comprehensive cancer center.

The researchers observed a three-fold increase in e-cigarette use from 2012 to 2013 (10.6 percent versus 38.5 percent). 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 percent versus 43.1 percent for e-cigarette users and non-users, respectively (excluding patients who were lost to follow-up).

"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 researcher Dr. Jamie Ostroff said in a statement.

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 counseling, and provide education about the potential risks and lack of known benefits of long-term e-cigarette use."

The findings were published in Cancer, a peer-reviewed journal of the American Cancer Society.