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The USPSTF Weighs In on CT Screening for Lung Cancer

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August 8, 2013

The USPSTF Weighs In on CT Screening for Lung Cancer

  1. Allan S. Brett, MD

The U.S. Preventive Services Task Force is requesting comments on its recommendation to provide computed tomography screening to current and former smokers.

  1. Allan S. Brett, MD

In late July, 2013, the U.S. Preventive Services Task Force (USPSTF) issued a “draft recommendation statement” on screening for lung cancer. The statement is open for public comment until August 26, 2013, after which, the USPSTF will issue a formal final recommendation.

For the first time, the Task Force is recommending lung cancer screening, largely because of the 2011 publication of results from the large, randomized National Lung Screening Trial (NLST; NEJM JW Gen Med Jul 14 2011), which is the only trial to show that CT screening lowers lung cancer mortality. The recommendation is for annual screening with low-dose computed tomography (CT) in healthy older people (age range, 55–79) with smoking history of at least 30 pack-years; former smokers are included if they quit during the past 15 years. This proposed target population essentially duplicates the enrolment criteria for the NLST. The USPSTF recommendation is grade B, indicating “moderate certainty” that screening is “of moderate net benefit.”

In the NLST, participants who were randomized to CT underwent three annual low-dose CT scans and were followed for an average 6.5 years. The statistically significant absolute reduction in lung cancer mortality was about 0.3%, and about 320 people were screened for every 1 death prevented. However, false-positive screening results were common. In the initial round of screening alone, 27% of patients exhibited CT abnormalities, the vast majority of which were not cancers. Most of those patients underwent additional scans or procedures — some of them invasive (NEJM JW Gen Med May 22 2013).

Before widespread screening is implemented, several issues require attention. First, the proposed criteria for screening — although simple and easy to remember — might not balance benefits and harms optimally. For example, in a recent analysis of the NLST cohort, researchers found that people in the lowest-risk quintile (according to a clinical prediction model that incorporates not only age, pack-years, and timing of smoking, but also family history and presence of emphysema) would derive virtually no benefit from screening. In contrast, in the two highest-risk quintiles, only about 170 people would have to be screened to prevent 1 death (NEJM JW Gen Med Jul 18 2013). Thus, we need refined criteria for screening, based on existing and validated risk-prediction models.

Second, the NLST screening centers used low-dose CT. Most modern CT scanners are capable of low-dose imaging, but right now, if you order a chest CT in most radiology departments, you likely will get a standard-dose study even if the indication is screening.

Third, CT screening will generate large numbers of scans with abnormalities that eventually will prove to be benign. If healthcare entities start advertising CT screening in the absence of a coordinated follow-up system, the aggregate harms of screening surely will outweigh the benefits. Expert clinical judgment will be necessary to ensure that follow-up imaging and invasive procedures (i.e., bronchoscopic and transthoracic biopsies) are done judiciously, safely, and cost-effectively. In my view, screening should be performed at centers where explicit formal collaboration exists between radiologists, pulmonary specialists, and thoracic surgeons.

  • Disclosures for Allan S. Brett, MD at time of publication Nothing to disclose

Reader Comments (6)

Jeanne Ashworth Physician, Oncology

This is in line with the benefits confreed by mammography, and certainly higher than that conferred by PSA testing, both of which continue to be widely utilized. Keep in mind that while some patients with early lung cancers might have died of other causes before becoming clinically apparent, the survival for Stage III and IV lung cancers (at which most lung cancers are diagnosed) is abysmal. In adddition, the costs incurred from treating early-stage disease are much lower than those with advanced disease.

ROBERT MCCORMICK Physician, Family Medicine/General Practice, retired

I most certainly agree with doctors Wells and Brown.

kimble poon, md Physician, Cardiology, Hawaii

Even if you attempt to restrict screening to high risk patients only, even moderate risk smokers will want to be screened-- who doesn't want to be checked to make sure they don't have a life-threatening disease? Esp bc it's non-invasive, unlike a colonoscopy. I fear a flood of patients will be requesting screening, or possibly exagerrating their smoking history. Or worse, physicians will be put in the position as withholding studies.

BRAD KAYS Physician, Internal Medicine, NEWPORT BEACH, CALIF

It is unfortunate that USPSTF has adopted this position. In an era of cost containment they have let the genie out of the bottle. I am encouraged that they are allowing an open forum to comment. I think this process is not cost effective, will lead to more harm than good and more expense with not enough benefit. However, I am forced into screening (sometimes) when I do not wish to. I could go on, but at this point I am opposed to this test with the proposed guidelines.

BRUCE WELLS Physician, Internal Medicine, Retire

Like most screening, the cost/benefit of screening using the criteria suggested by the USPSTF (vis-a-vis the NLST) shows criteria for high risk individuals. Where do we set the cut-off number to screen to save one life? I am of the opinion that low dose screening for lung cancer is not yet ready for prime time.

Ann Brown MD Physician, Internal Medicine

In an era of Choosing Wisely which encourages decreased utilization of imaging studies , I find it ironic that the USPTFS has recommended any annual CT screenings for cancer prevention. I still fear too much harm may be done by pursuing false positive findings.

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