CT screening has little effect on smoking habits

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NEW YORK (Reuters Health), May 22 - The results of a study published in the May issue of Thorax suggest that CT screening has little effect on the smoking habits of patients at one-year follow-up compared with smokers who do not undergo screening. CT screening neither induces more smoking nor promotes cessation, the researchers conclude.

An exception was seen among smokers who underwent CT screening and were asked to return within three months for a repeat screening due to initial CT findings. This subgroup had higher quit rates and lower relapse rates compared with the smokers in the screening or control groups.

"Lung cancer screening programs with low-dose CT scanning are currently being evaluated in the hope of detecting lung cancer at an earlier stage and thereby improving survival," Dr. H. Ashraf, of Gentofte Hospital, Copenhagen, and colleagues write. "To date, no randomized controlled trials have investigated the effect of lung cancer screening programs on participants' smoking habits."

This led researchers to examine whether participation in the Danish Lung Cancer Screening Trial (DLCST) affected smoking habits. The DLCST is a five-year study that included 4,104 individuals randomly assigned to annual low-dose CT screening of the chest (n = 2,052) or to no intervention (n = 2,052). The authors report the results of one-year follow-up.

Study participants were healthy current and former smokers with a history of at least 20-pack years. Former smokers were defined as those who had not smoked for at least four weeks prior to the baseline screening visits. Exhaled carbon monoxide levels were used to verify smoking status. The investigators also conducted lung function tests, nicotine dependency, and motivation to quit smoking.

Quit rates at one year were 11.9% in the CT group and 11.8% in the control group. Overall, 10.0% of former smokers in the CT group and 10.5% in the control group relapsed.

A high motivation to quit, low dependency, and low ratio of forced expiratory volume in one second to forced vital capacity significantly predicted smoking cessation. Other significant predictors of smoking cessation included low pack years, older age, longer period of abstinence, and CT findings necessitating three-month repeat CT scans.

Positive baseline CT scans were observed in 173 subjects (129 current and 44 former smokers). These patients were rescanned three months later. The quit rate for baseline smokers in the CT-positive group was 17.7%, compared with 11.4% for those with no significant CT findings upon repeat screening. The corresponding percentages for relapse rates were 4.7% and 10.6% (p < 0.01).

"More intensive counseling and pharmacological treatment for smoking cessation should be administered in future lung cancer screening trials in an attempt to increase the quit rate," Ashraf and colleagues conclude. "In screening trials, more focus should be put on smoking cessation and motivating smokers to stop as early as possible."

Thorax 2009;64:388-392.

Last Updated: 2009-05-21 10:50:59 -0400 (Reuters Health)

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