Consensus is starting to build that long-time smokers should have annual CT-based screenings to reduce lung cancer mortality, a researcher said here.
A series of studies suggesting a mortality reduction in high-risk current and former smokers who underwent screening - capped by last year’s report from the National Lung Screening Trial (NLST) - has built a case in favor of screening, which is still officially discouraged in primary care, said James Jett, MD, of National Jewish Medical Center in Denver, at the annual meeting of the American College of Physicians.
He said a forthcoming joint evidence review by several organizations - the American College of Chest Physicians, the American Society of Clinical Oncology, the National Comprehensive Cancer Network (NCCN), and the American Cancer Society - had determined that screening in high-risk patients has value, but stopped short of a definite recommendation.
According to Jett, their report, which is under review at the Journal of the American Medical Association, will include the following statement: “We conclude that low-dose CT screening may benefit individuals at an elevated risk for lung cancer but uncertainty exists about potential harm and generalizability of the results.”
Last November, in the wake of the NLST findings of a 20% reduction in lung cancer mortality and a 6.7% reduction in all-cause mortality associated with screening, the NCCN had issued a less qualified endorsement of CT-based screening for high-risk individuals.
It said such individuals should be screened, but only after discussing the risks - primarily the high likelihood of false-positive results and the unnecessary procedures that may follow - with their physicians.
“High-risk” was defined in two ways: a patient age 55 to 74 with a smoking history of at least 30 pack-years and who had smoked within the previous 15 years; or a patient age 50 and older with a smoking history of at least 20 pack-years and another risk factor other than second-hand smoke exposure. Such risk factors are mainly occupational exposures to lung carcinogens such as asbestos.
Jett opened his talk with statistics on the scale of the lung cancer problem in America. It’s by far the single biggest cancer killer - the approximately 160,000 deaths each year from the disease equal the total of the next four cancers with the highest death tolls (colorectal, breast, pancreas, and prostate).
Lung cancer, he declared, “isn’t just a cancer problem. It’s the cancer problem.”
He also noted that screening has reduced mortality associated with several of the most deadly cancers, which has naturally raised interest in screening for lung cancer.
The problem has been the lack of a technology with acceptable sensitivity and specificity. Chest x-rays can easily miss early-stage tumors lurking near other structures and cannot distinguish malignant tumors from benign uncalcified nodules.
Low-dose CT scans provide much greater resolution and have improved the sensitivity substantially, Jett said. Compared with chest x-rays, CT scans detect more tumors, smaller tumors, and earlier-stage tumors, offering at least the possibility of more effective curative treatment.
But the specificity problem remains. Moreover, he said, there is the issue that also is currently dogging treatment of breast and prostate cancer, namely the question of how to distinguish aggressive malignancies from more indolent tumors that may not need treatment.
Jett also reviewed the burden created by false-positive findings from imaging-based screens. In the NLST, some 95% of positive screens by CT were determined to be false (that is, due to nonmalignant lesions). Most of these only engendered additional imaging scans, but a substantial minority required biopsies and, in some cases, resection before the lesions were determined to be benign.
Until the NCCN officially backed screening in high-risk patients, the official line from medical societies was that it had no real clinical value.
With the results from the NLST and other large trials, that viewpoint is now starting to shift, but with some hesitation and many caveats, Jett suggested.
For example, the concluding statement from the four societies that they hope to publish in JAMA contains the caution about “generalizability.” Jett said that was because all the trials were conducted in academic medical centers with very strict protocols.
It’s unclear whether the same results could be achieved in broader, less homogeneous clinical settings, he said. Jett also indicated that the risks remain uncertain, including those of radiation exposure as well as from possibly unnecessary treatment that may result from screening.
Another practical barrier to screening is that annual CT scans are relatively expensive and most insurers do not currently cover them. Jett said he knew of only one large insurance provider, Wellpoint, that pays for screening CT scans.
“I tell patients you have to pay for it yourself,” he said.
Jett reported relationships with Pfizer, Bristol-Myers Squibb, Oncimmune, and Metabolomx.
By John Gever, Senior Editor, MedPage Today