James L. Mulshine, MD
When the US Preventive Services Task Force (USPSTF) recommended last year that asymptomatic, high-risk individuals should receive annual screening for lung cancer with low-dose computed tomography (LDCT), it made a healthy decision for the American population, according to James L. Mulshine, MD.
Though the decision has become the subject of debate since the Medicare Evidence Development & Coverage Advisory Committee (MEDCAC) recommended in late April that Medicare should not cover the screening,1
the strategy offers more benefits than risks and should be supported, Mulshine said during a keynote address this morning at the 15th Annual International Lung Cancer Conference in Huntington Beach, California.'
“Tobacco-related disease is the source of 50% of premature death in our society, and the leading cause of that death is lung cancer, so we’re talking about a big public health problem. Screening—the ability to find this disease when it is potentially still curable—is a very logical strategy. I don’t think screening is controversial at all; I think there are just some educational gaps.”
Mulshine is a professor, Associate Provost for Research, and Vice President at Rush University Medical Center in Chicago. He also serves on the Board of Trustees for the Lung Cancer Alliance and Prevent Cancer Foundation and on the Scientific Advisory Board to I-ELCAP (International-Early Lung Cancer Action Project).Rationales for Screening
In addition to catching disease early, screening high-risk populations for lung cancer can work in tandem with diagnostic tools to identify those likely to struggle with more aggressive disease, Mulshine told his audience. He added that CT screening can help in the development of new drugs for early management of disease; he cited a trial that evaluated the effect of the VEGF inhibitor pazopanib preoperatively in patients with early-stage, non-small cell lung cancer, using CT to track changes in tumor volume and diameter.2
An added benefit is that the screening can simultaneously look for chronic obstructive pulmonary disease and obstructed coronary arteries at the same imaging cost, he said.
Mulshine said the need for screening is notable among people who have smoked. In that group, he said, the risk of developing lung cancer “never returns to normal.” For a 75-year-old who has never smoked, the risk is <1%; for someone who stopped smoking at age 30, the risk is <2%; for someone who stopped at age 50, the risk is about 6%; and for someone who is still smoking, it’s 16%, he said.3
An average 123,800 people in the United States die each year of lung cancer attributable to smoking, he said.4
“Forty-five million to 50 million people in the United States have stopped smoking, and they have an area under the curve of increased risk of lung cancer that is nonresolvable,” Mulshine said. “That explains why, in academic centers, more people are diagnosed with lung cancer as former smokers than as current smokers. The idea that stopping smoking takes care of everything is misguided. It only decreases the accrual of more risk. So there is justification for lung cancer screening, as well as smoking cessation, at least in that population and the current smoking population.”Costs and Benefits of Screening
The USPSTF gave the screening strategy a B rating, rather than an A, because of concern over some potential drawbacks, including radiation exposure, misclassification, and overdiagnosis.
Mulshine noted that the doses of radiation used in the screening, which were low in the clinical trial that led to the recommendation, are perhaps even lower in practice now.
As far as overdiagnosis, he said, there is information in the literature about how to minimize that.
Currently, a CT scan for lung cancer is considered indicative that an invasive workup is needed if a nodule is found that is 5 mm in diameter or larger. A recent study,5
however, considered what would happen if a larger nodule was needed before a workup was ordered. With a 5-mm cutoff, investigators found, 3396 scans lead to the diagnosis of 119 actual lung cancers, while with a 9-mm cutoff, just 838 scans would have to be done to reveal 111 actual lung cancers.
“Instead of moving from a situation where very few patients have cancer, as you move to 8 mm and 9 mm, you’re approaching 10%,” Mulshine said. “You radically increase the efficiency.”
He said these kinds of adjustments can be made based on “rapid learning,” or optimizing management of a strategy by tracking results and acting on them. The NCCN has already changed its treatment guidelines to suggest a 6-mm cutoff, Mulshine pointed out.
“You do this,” he said, “because a major concern about any population-based management is cost.”