NEW YORK (Reuters Health) – Emphysema that’s visible to a doctor reading a computed tomography (CT) scan is associated with an increased risk of lung cancer, according to a report online March 19 in Lung Cancer.
There was no such increased risk when emphysema was detected by a computer interpreting the scan.
“Our suspicion is that radiologists and automated computer software may detect different types of emphysema,” Dr. Benjamin M. Smith from McGill University, Montreal, Canada told Reuters Health in an email. “With respect to lung cancer risk, it would appear radiologists detect the type of emphysema that matters. Currently we are investigating the differences between emphysema detected by radiologists and by computer software. This research will shed new light on the complexity of emphysema and its association with lung cancer.”
Dr. Smith and colleagues conducted a systematic review and meta-analysis of seven published studies to explore the evidence of association between emphysema detected on CT and lung cancer risk.
Five studies of chest CT in patients without a history of lung cancer met pre-specified quality requirements. They included a total of 7,368 subjects, including 2809 with emphysema detected on CT and 870 diagnosed with lung cancer. The pooled odds of lung cancer were 2.11-fold higher among patients with emphysema on CT compared to those without emphysema.
When the patients were stratified by detection method, the pooled odds of lung cancer were 3.5 when emphysema was detected visually by an individual interpreting the CT scan, whereas there was no significant increase in the odds of lung cancer when emphysema was detected using quantitative densitometry.
“Patients found to have emphysema detected visually on CT scan are at increased risk of developing lung cancer,” Dr. Smith concluded. “For such patients, smoking cessation should be strongly encouraged. I would also advise them of the potential benefits (and risks) of participating in lung cancer screening program, highlighting that having emphysema, in addition to smoking, puts them at particularly high risk of developing lung cancer.”
Lung Cancer 2012.