CT Screening for Lung Cancer an Important Life-Saving Tool

Author(s):

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

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,¹the 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.”

When it comes to cost, Mulshine said that CT screening in this population is less expensive than that associated with screening for breast, cervical, or colorectal cancers, and that more value is gained. Based on an actuarial study, he said, the screening costs private insurers about 76 cents per plan member per month, with a cost per life-year saved of about $18,000.⁶ Meanwhile, screening for breast cancer adds about $3 per member per month, Mulshine said.

Screening Recommendations

In its recommendation that the screening should be conducted,⁷ the USPSTF defined high risk individuals as those aged 55 to 80 years with a 30 pack—year smoking history who currently smoke or quit within the past 15 years. The panel recommends discontinuing screening when an individual stops smoking for 15 years or develops a health problem that significantly reduces life expectancy or the capacity/desire to receive curative lung surgery. Further, the panel warned that its analysis did not yield enough evidence to support screening low-risk individuals.

The USPSTF recommendation was largely based on the National Lung Screening Trial, which involved 53,454 high-risk patients aged 55 to 74 years who were randomized to 3 years of annual screening with either LDCT or standard chest x-ray.⁸ Over 6.5 years of follow-up, patients screened with LDCT had a 20% reduction in mortality compared with those in the x-ray group (P = .004).

The USPSTF also considered 8000 other papers on the subject in making its decision, Mulshine said.

The year before the USPSTF made its recommendation, the strategy had been endorsed by the NCCN.

Yet MEDCAC members voted that the benefits of screening will not outweigh the harms; that there is a lack of evidence supporting the value of the screening; and that there is too high a likelihood of mistakes or oversights within radiology departments that will result in the failure to minimize the harms potentially associated with screening.

The Controversy

Based on the USPSTF’s recommendation, the government, under the Affordable Care Act, has mandated that all private health insurers submit plans to the US Department of Health and Human Services outlining how they will provide full coverage for the screening with no copay for people in the target population, Mulshine said. Many private carriers are already covering the screening, he said.

Meanwhile, the Center for Medicare & Medicaid Services (CMS) expects to issue a draft decision on whether it sees value in the screening in November, followed by a final decision in early 2015.

CMS has a right to decide against the screening, but Mulshine guessed that it will either endorse the screening or fund it for patients in the target group who sign up for a registry, so that more evidence can be gathered.

That’s because, if CMS decided Medicare would not fund the screening, a disparity would be created between people insured by Medicare and those covered by private insurance companies, Mulshine said.

“I don’t think CMS is not going to cover this, so the discussion with CMS right now is whether it goes forward with continuing evidence development or not, but there’ll be a coverage decision by November. After that, I think you’ll see a much bigger uptake.”

References

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