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Spiral CT cuts risk of death from lung cancer?

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A new study released recently in Radiology found heavy smokers who were screened with low-dose helical computed tomography or spiral CT were 20 percent less likely to die than those who were screened with chest radiography.

The study funded by the National Cancer Institute and led by Constantine A. Gatsonis at Brown University and colleagues also found those receiving spiral CT screening were 7 percent less likely to die from all causes.

Most trial studies found spiral CT screening did not reduce the risk of death from lung cancer.

One trial published in the Sep 1, 2009 issue of American Journal of Respiratory and Critical Care Medicine concluded low-dose helical computed tomography did not reduce risk of death from lung cancer.

During the trial led by Infante M. and colleagues from Istituto Clinico Humanitas in Milan, Italy, 20 of 1276 men screened with spiral CT and 20 of 1,196 controls died of lung cancer whereas 26 screened and 25 controls died of other causes, respectively.  The number of advanced lung cancer cases in the study arm was the same as that in the control arm.

The trial involved 2,472 men aged 60 to 75 who had a smoking history of 20 or more pack-years. All subjects received a chest x-ray and sputun cytology examination at baseline. Then the screening arm subjects were screened annually for 4 years while controls received a yearly medical examination only.

The researchers found during an average 33-month follow-up, 60 subjects in the study arm and 34 control subjects were diagnosed with lung cancer.  Resectability rates were found similar in both groups. More cases of stage 1 lung cancer were found in the study group through. 

Muralibrishna Gopal MD and colleagues of Albert Einstein College of Medicine/Montefiore Medical Center reported in the Aug 2010 issue of Journal of Thoracic Oncology that their review of six randomized controlled trials found no evidence in favor or against the use of spiral CT screening for lung cancer in terms of its effect on the lung cancer mortality.

Gopal et al. found screening for lung cancer using spiral CT resulted in nearly 4 times as many stage 1 lung cancers and 4 times as many total lung cancers as those who did not receive the screening. 

Spiral CT also led to 3 times as many false positive nodules and nearly 4 times as many unnecessary thoracotomies for benign lesions.

Of 1000 individuals screened with spiral CT for lung cancer, the review study also found, 9 stage 1 non-small cell lung cancer, 235 false positive nodules were detected and four thoracotomies for benign lesions were performed.

It is unknown how the study led by Gatsonis, which found spiral CT benefits reduced risk of death from lung cancer in heavy smokers, would affect the current guidelines about lung cancer screening.  

Gatsonis' study only followed subjects in a few years after three annual screenings.  No one knows for sure what will happen to the patients after repeated screenings for 5, 10, 15 or 20 years? Radiation used in spiral CT and even in chest radiography per se can boost cancer risk and caused vascular diseases.

Generally, expert groups do not recommend any type of lung cancer screening because no evidence from any quality study suggests such a screening would reduce the risk of death from lung cancer, which kills more people than breast, colorectal, pancreatic and prostate cancers combined.

Regardless, many primary care physicians would recommend spiral CT screening for asymptomatic individuals, according to a new survey published in the Nov 2010 issue of American Journal of Preventive Medicine.

Jimmy Downs

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