One of the most extensive and ambitious medical-screening trials in US has been stopped. It’s because of good news: Low-dose helical CT (LDCT) exams can cut lung-cancer deaths by as much as 20%, compared with chest radiography alone, according to early results from the National Lung Screening Trial (NLST). The NLST was halted in early November, 2010, after researchers determined that a 20.3% reduction in mortality rates occurred among patients examined using LDCT, compared with mortality rates among patients who underwent conventional chest radiography.
The trial lasted eight years and included nearly 53,500 participants between the ages of 55 and 74 who were asymptomatic current or former smokers, each with at least 30 pack-years of cigarette consumption prior to enrolling in the study.
The NLST participants were separated into two groups randomly, with one group receiving LDCT scans and the other, chest radiographs. The study confirmed that LDCT was better at finding small cancers in the smoking cohort than chest radiography was. The results further showed that significant numbers of current or former smokers can be saved from lung-cancer death if their tumors are discovered and treated early enough.
Denise R. Aberle, MD, a principal investigator in the study, notes, “I would say the results are very exciting. This is the single most significant medical intervention that has been done in patients to reduce lung-cancer mortality in several years.” Aberle adds, however, “CT is not a panacea. You can’t suggest it will save a life if there is high risk of lung cancer. That needs to be understood. This screening reduces mortality, but it by no means guarantees survival.”
Aberle is a professor of radiology and vice chair of research in the thoracic-imaging section at the University of California–Los Angeles (UCLA). She is also the NLST’s principal investigator for the ACR® Imaging Network (ACRIN).
The NLST was initiated jointly by the National Cancer Institute (NCI) and ACRIN, with NCI funding. The recommendation to end the study was taken by the trial’s data and safety monitoring board after results confirmed the life-saving benefits of LDCT over x-ray. It was a decision Aberle agreed with. She says the 20% reduction in mortality in the CT patient group was statistically significant and crossed a “+predetermined boundary” under which participants would be notified of screening benefits in one arm or the other. “We sent letters to all 54,000 participants,” she added.
The Biggest Killer
According to a recent report¹ on the NLST, lung cancer kills more than 150,000 people annually in the United States. The smoking and lung-cancer impact on health care isn’t going away any time soon, but the results of the NLST suggest that thousands of deaths among current and former smokers could be averted with LDCT screening and treatment. The problem, which won’t be solved overnight, is how to implement such a program. Who will pay for it is a major consideration.
CT scans, as Aberle notes, are expensive. Even for the NLST participants, she says, each LDCT cost about $300. On the open market, costs can be significantly higher. Costs are high enough that even the NLST participants in the radiography arm are on their own if they want to be rescreened using CT, Aberle says; the National Cancer Institute (NCI) doesn’t have the funding to screen them. She says, “We advised the radiography patients to consider CT, in conjunction with their physicians.”
Aberle urged caution for patients and physicians who look at the NLST results with an eye toward ordering an immediate CT screening exam. There are currently no national screening guidelines, she says. Moreover, reimbursement might be a problem, whether from private insurers or from Medicare.
Aberle also says that she’s concerned that imaging providers might be too quick to offer CT screening based on the NLST results. “There is an opportunity for capitalizing on this in ways that are not in the interest of the public health,” she says. “There are financial incentives to offer screening.”
Aberle cautions patients and physicians to seek qualified imaging providers and health networks before ordering screening. Provider decisions should not be made without forethought, she says. Imagers should have chest-CT expertise, and provider networks should be capable of dealing with abnormal findings and should meet standards/guidelines for practice following positive screenings,