Researchers have found that 9.3 percent of the U.S. cancer survivors smoke years after diagnosis. Around 83 percent of these smokers use about 14.7 cigarettes per day.

The study, by researchers at the American Cancer Society, shows that cancer survivors must be counseled about the effects of smoking.

Smoking doesn't just raise lung cancer risk, but also increases risk of kidney, liver and ovary cancers. Smoking tobacco also reduces effectiveness of cancer treatment and increases the probability of cancer relapse. The researchers say that this is the first study looking at the long-term records of smoking habits in cancer survivors, according to a news release.

For the study, researchers obtained data from 2,938 patients nine years after their diagnoses. The participants were part of the American Cancer Society's Study of Cancer Survivors-I (SCS-I). The team found that those who were less educated, young or alcoholics were more likely to smoke cigarettes even after cancer diagnosis.

"Smoking is addictive and having cancer does not guarantee that you will stop, even if that cancer was directly tied to your smoking," said Lee Westmaas, PhD, director of tobacco research at the American Cancer Society (ACS) and lead author of the study, according to a news release. "We need to do more to intervene with these patients."

The researchers also found that about 46.6 percent of the participants said that they would want to quit smoking; about 10 percent said that they did not plan on quitting and 43.3 percent were not sure. According to the team, people who were married, old or those who smoked more cigarettes were less likely to quit smoking after cancer diagnosis.

"We need to follow up with cancer survivors long after their diagnoses to see whether they are still smoking and offer appropriate counseling, interventions, and possible medications to help them quit," said Lee Westmaas, according to a news release.

The study is published in the journal Cancer Epidemiology, Biomarkers & Prevention.