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Posts Tagged ‘spiral CT lung scans’

Lung screening scans for smokers

Posted by medconsumers on July 6, 2011

At the end of last year, the National Cancer Institute announced that it had stopped its lung screening trial earlier than planned. The reason: fewer lung cancer deaths among participants screened with CT lung scans compared with those screened with chest x-rays. This landmark trial is the first to show that screening can reduce lung cancer mortality in people with a history of heavy smoking. Because the National Lung Screening Trial (NLST) is taxpayer-funded, its results were reported directly to the public on the NCI website. But the NCI also made it clear that the harms associated with lung screening would not be known for months. The missing information came in this week’s issue of the New England Journal of Medicine.

The harm of screening lung scans is primarily, but not limited to, false alarms. That is, of course, the risk of all screening tests. Mammography, for example, has a high rate of false-alarms (false-positives), and studies show that most women accept this as the “price to pay” for what they perceive as the lifesaving benefit for mammography. But unlike a biopsy of the breast, which is, after all, an appendage, a needle biopsy of the lung is much riskier. Complications include death (rare, we are told) and collapsed lung (common for smokers and former smokers). Some NSLT participants went on to more invasive, risky procedures like thoracotomy and mediastinoscopy for abnormalities that turned out not to be cancer.

If you are a smoker or former smoker, your decision to be screened with a CT lung scan should involve weighing the benefit against the harms. The first thing to consider is whether you fit the profile of the people who participated in the NLST. They were male and female smokers and former smokers, age 55 to 74 years*, who were symptom-free at the start of the trial. All had smoked one pack a day for 30 years, or two packs a day for 15 years, or three packs a day for at least 10 years in the previous 15 years. The more than 53,000 participants were randomly assigned to have either a low-dose spiral computer tomography (CT) lung scan or a standard chest x-ray annually. The trial was stopped at 3 years and continued to followed participants for 3 ½ more years.

There were 356 lung cancer deaths among the more than 26,000 participants assigned to receive a spiral CT lung scan, compared to 443 among the 26,000 participants given chest x-rays (either way, a surprisingly low number of deaths for such high-risk people followed over a six-year period). But this benefit came at a huge cost in terms of money, health, and worry to the one in four people, whose scans indicated cancer, leading to more tests, a needle biopsy, and in some cases, an invasive procedure before a false-alarm was ultimately determined in the overwhelming majority of cases. False-alarms occurred in both groups, but scanning found far more abnormalities that looked like cancer before they were ultimately judged to be benign. The scans cost a couple of hundred dollars each; the “cascade” of tests that can follow are costly.

Though “low-dose” is part of its description, CT scans involve a radiation dose far higher than a standard chest x-ray but less than the standard CT scan click here. Whether annual spiral CT lung scanning itself causes lung cancer is yet to be determined. For screening mammography, the NCI estimate is: There are between 10 and 32 radiation-induced breast cancers for every 10,000 women exposed to accumulated doses of radiation received over the years from multiple mammographic examinations.

Although hospitals have already started targeting smokers with advertising for annual screening lung scans, the authors of the NLST, led by Christine Berg, MD, of the NCI’s Early Detection Research Group, do not think the technology is ready for prime time both for cost-effectiveness and safety reasons.  One concern—and it applies to all research projects—is the care delivered in the context of a clinical trial is likely to be far better than that received in the everyday practice of medicine. In the editorial that accompanied this study, Harold C. Sox, MD, Dartmouth Medical School, points out that the NLST took place at 33 academic medical centers, but the diagnostic testing and cancer treatment took place in the community, aka the real world. Dr. Sox is encouraged by the fact that the rate of death associated with diagnostic procedures was low because it indicates that diagnostic care in the community is good. However, where it concerns the radiologists who read the scans for the NLST participants, Dr. Sox suggests their skills were probably far higher than their counterparts practicing in the community. The NLST radiologists “had extensive training in the interpretation of low-dose CT scans and presumably a heavy low-dose CT workload.”

Dr. Sox wrote that he agreed with the authors of this study. “…policy makers should wait for more information before endorsing lung-cancer screening programs.”

*Participants in their seventies were underrepresented in this study (fewer than 3% of all). This means that less is known about the safety and effectiveness of screening people over age 70.

See this August 7, 2011 lung screening addition to TheNNT.com website. 

Maryann Napoli, Center for Medical Consumers©

Posted in breast cancer, Cancer, hospitals, Men's Health, radiation exposure, Scans and X-rays, Screening, surgery, testing, Women's Health | Tagged: , , , , , , , | Leave a Comment »

Were you, or are you, a heavy smoker?

Posted by medconsumers on November 14, 2010

Early this month a federally-funded trial found that screening current or former smokers can reduce their mortality. There were 20% fewer lung cancer deaths among those given low-dose spiral CT lung scans. Consequently, the trial was stopped early, and the results were announced directly to the public on the National Cancer Institute’s (NCIs) website. Until this news broke, no study had proven lung cancer screening can save lives.

The National Lung Screening Trial is sponsored by the NCI and conducted by the American College of Radiology Imaging Network. Participants included more than 53,000 men and women ages 55 to 74 who were heavy smokers. All had smoked at least 30 pack-years—i.e., they had smoked one pack a day for 30 years, or two packs a day for 15 years, or three packs a day for at least 10 years. All were randomly assigned to receive either annual lung scans or standard chest X-rays. None had symptoms of lung cancer when the trial started recruiting in 2002. At the time the trial was stopped, there were 354 deaths from lung cancer in the CT-scanned group and 442 lung cancer deaths in the group given chest X-rays.

The NCI website provides cautions about the new results. For example, there was a 7% reduction in deaths from causes other than lung cancer. But it should not be seen as a call to arms by radiologists eager to screen all middle-aged and older people. Instead, this 7% reduction in deaths is relevant only to middle-aged and older people who have a smoking history similar to that of the study participants. Another caution involves the risks of false-alarm biopsies and treatment of lung abnormalities mistaken for cancer—both can lead to risky lung surgery. (To see how quickly these cautions were ignored, click here.)

The National Lung Screening Trial is not to be confused with another screening study called the International Early Lung Cancer Action Program, or ELCAP. Published in a 2006 issue of The New England Journal of Medicine ELCAP showed that spiral CT scanning can find more potentially curable lung cancers (i.e., early stage). It did not, however, find a reduction in lung cancer deaths in the ten-year duration of this study. Its lead author Claudia Henschke, M.D, took this promising but not definitive finding and went on to claim that most lung cancer deaths could be prevented in heavy smokers through widespread use of CT scans. Over the years, she has gotten a fair amount of media attention with this message despite the consensus among screening researchers that mortality reduction is the only valid outcome for proving a screening test’s worth.

Two years after publication, ELCAP’s results were tarnished by the conflicts of interest associated with its co-authors, Drs. Henschke and David F. Yankelevitz who receive royalties from patents related to screening scans. What’s more, their study was partially funded by $3 million from a cigarette company, as reported in The New York Times (click here).

The newly announced National Lung Screening Trial may have settled the question of whether screening lung scans can save lives, but another controversy has only just begun. Does the benefit of saving one in every 300 heavy smokers outweigh the risks of false-alarms affecting one in four? Because this trial was stopped early, a complete analysis of the harms will not be ready for months.

Maryann Napoli, Center for Medical Consumers©

Posted in Cancer, Men's Health, Scans and X-rays, Screening, Women's Health | Tagged: , , , | Leave a Comment »

Spiral CT Lung Scans for Smokers and Former Smokers

Posted by medconsumers on May 1, 2005

The introduction in the 1990s of a high-tech procedure for scanning the lungs of smokers and former smokers raised hopes that it would spare many of them a lung cancer death. A new study reported in the journal Radiology, however, confirmed the fears of a few physicians who have publicly questioned the premature promotion of this test. Its potential for harm has been verified in the study conducted by researchers at the Mayo Clinic in Rochester, Minnesota.

The spiral computed tomography, or CT, lung scan provides three-dimensional images that allow doctors to find many more tiny lung nodules than would be apparent on the standard chest x-ray. And that is the problem. The high number of nodules and other lung abnormalities found in this new study required extensive investigation and, in many instances, risky surgery before most of them could be classified as benign. This high rate of false alarms can be justified only by a screening test that offers a substantial reduction in lung cancer deaths. And the jury is still out on this important point.

Too Many False Alarms

Funded by the U. S. National Cancer Institute, the study included over 1500 men and women who were given annual CT lung scans. 61% of them were current smokers and the rest were former smokers. After five years, the research team led by Stephen J. Swensen , MD, at the Mayo Clinic in Rochester, Minnesota , found that the false-positive (false-alarm) rate was extremely high. Nodules—749 altogether—that proved to be benign were found in 69% of the participants. In some cases, the lung abnormalities proved to be cancer, but they were a type that would never produce symptoms or become life-threatening.

“Intervention for benign nodules is common and has substantive financial, mortality, morbidity, and quality of life costs,” wrote Dr. Swensen and colleagues. A lung biopsy, for example, is a potentially risky procedure that is typically ordered to rule out lung cancer. A small amount of lung tissue is removed through a telescope-like tube that is inserted down the windpipe (a bronchoscopy) or via a needle inserted through the chest wall. Occasionally, a larger amount of lung tissue must be biopsied which requires major surgery (thoracotomy or thoracic surgery), with the potential for severe complications in people with ailments common to smokers, such as heart or lung diseases.

Lifesaving Benefit Unproven

Here are the Mayo Clinic study’s conclusions: “Screening for lung cancer offers the possibility of reducing mortality from lung cancer. Our preliminary results do not support this possibility and may raise concerns that false-positive results and overdiagnosis could actually result in more harm than good.” They explained overdiagnosis as the detection of slow-growing lung cancers that “a patient dies with and not from,” a phenomenon that is not limited to the lungs. The breast, prostate, thyroid and other organs also contain cancers that would never become symptomatic or deadly if they went undiscovered.

Researchers suspect overdiagnosis whenever a study like this one finds a high number of early-stage would-be cancers but no reduction in the number of people diagnosed with more advanced disease. This strongly suggests that the overwhelming majority of these suspicious abnormalities would never have progressed to fatal lung cancer.

The study was not designed to come to a conclusion regarding the ability of the CT scan to reduce the rate of lung cancer deaths because there were no unscreened participants to serve as a comparison to the people given lung scans. There were only nine lung cancer deaths but 40 deaths from other causes. The investigators, however, point out that the lung cancer death rate was similar to that of an earlier study called the Mayo Lung Project.

The definitive answer regarding the spiral CT scan’s potential contribution to reducing the lung cancer death rate is expected from another National Cancer Institute- financed project called The National Lung Screening Trial. This is the first trial to compare the new technology with the old. 50,000 current or former smokers have already been enrolled. They have been randomly assigned to receive either a chest x-ray or a CT lung scan. After one or two years, each group will have the same screening procedure again. Results will not be published before 2010.

Trial Sponsor Issues Warning

The National Cancer Institute warns about the risks of screening on its Web site:

“Conventional wisdom suggests that the smaller the tumor, the more likely the chance of survival. But no scientific evidence to date has shown that screening or early detection of lung cancer actually saves lives. The National Lung Screening Trial, because of the large number of individuals participating and because it is a randomized, controlled trial, will be able to provide the evidence needed to determine whether spiral CT scans are better than chest X-rays at reducing a person’s chances of dying from lung cancer.”

Maryann Napoli, Center for Medical Consumers ©

Posted in Cancer, Men's Health, radiation exposure, Scans and X-rays, Screening, Women's Health | Tagged: , , , , , , , | Leave a Comment »

 
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