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Monday, November 8, 2010

Radiation screening promoted to detect lung cancer

Annual CT scans of current and former heavy smokers reduced their risk of death from lung cancer by 20 percent, according to the largest study ever done of lung cancer screening.

The effectiveness of CT scanning for lung cancer has been debated for years because the test can pick up lung abnormalities like scars from past infections that are not cancer. Such irregularities "are common in heavy smokers and can result in costly anxiety-producing tests. CT scans use coordinated X-rays and a dye to provide three-dimensional views.

Chest X-rays have never been shown to save lives, according to Ned Patz, a professor of radiology at Duke University Medical Center who helped design the National Lung Screening Trial, a $250 million government-funded study conducted by the American College of Radiology Imaging Network and the cancer institute.

The trial involved more than 53,000 people ages 55 to 74 who had smoked at least 30 pack-years — one pack a day for 30 years or two packs a day for 15 years. Ex-smokers who had quit within the previous 15 years were included in the group. Each was given either a standard chest X-ray or a low-dose CT scan at the start of the trial and then twice more over the next two years. Participants were followed for up to five years. There were 354 lung cancer deaths among those who received CT scans and 442 among those who got X-rays.

The study found that for every 300 people who were screened, one person lived who would otherwise have died during the study. But one-quarter of those given CT scans were found to have anomalies, nearly all of which were benign. These false signals generally led to more worry, more CT scans and sometimes to lung biopsies and thoracic surgery.

Oncologists predict the study’s results would soon lead to widespread use of CT scans, in particular for older smokers, who have a one in 10 chance of contracting lung cancer.

But health officials involved in the study refused to endorse widespread screening of current or former smokers, saying more analysis of the study’s results is needed to further identify who benefited most.

Deaths due to all causes declined by 7 percent among study participants who received CT scans, suggesting the tests helped to detect other life-threatening diseases besides lung cancer.


“What we have found is that low-dose CT scan also gives information on cardiovascular disease, emphysema” and other pulmonary diseases, said Dr. Claudia Henschke, a clinical professor of radiology at Mount Sinai Medical Center and a longtime advocate for use of CT to screen for lung cancer. “Those are the three big killers of older people. There is just tremendous potential.”

Lung cancer will claim about 157,000 lives this year, more than the deaths from colorectal, breast, pancreatic and prostate cancers combined. Most patients discover their disease too late for treatment, and 85 percent die from it.

Dr. Grout’s comment:

Some might ask if this is a case of vested interests looking to maintain their market share – mammograms are ineffective and deliver too much radiation, so let’s screen for lung cancer instead.  But I don’t think so. This one actually makes sense, because the recommendation is for a targeted population of smokers (current and former).

Until we have eliminated smoking from the consciousness of the race, people will continue to become addicted to nicotine, and will continue to develop the horrifically devastating disease of lung cancer, and will continue to die agonizing deaths. When they stop smoking, the risk of cardiovascular disease quickly returns to the baseline of non-smokers. However, the risk of lung cancer continues for many years.


If a CT scan of the chest can detect potential disease in current or former smokers early enough to treat it surgically with reasonably anticipation of cure, then indeed the potential for saving lives is well worth the extra radiation delivered by the spiral CT scan. A 20% survival benefit far exceeds the measured 2% survival benefit obtained through routine mammography screening.

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