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CT Screening Can Reduce Lung Cancer Deaths; Now What?
By Jim Knaub

“This is the first time that we have seen clear evidence of a significant reduction in lung cancer mortality with a screening test in a randomized controlled trial.”

— Christine Berg, MD, of the National Cancer Institute

A 20% reduction in cancer deaths is significant. In the past, one big argument against screening for lung cancer was that there were no well-controlled studies showing that screening actually changed outcomes by reducing deaths. The National Lung Cancer Screening Trial (NLCST) followed 53,000 current or former smokers and showed that reduction.

“This is good news,” Dana-Farber Cancer Institute thoracic oncologist Bruce Johnson, MD, told USA Today. “The reduction in deaths is comparable to mammograms, which reduce deaths by 14% to 15%.”

But results showing fewer deaths alone will not make CT scanning for lung cancer a widespread practice. There are real issues—particularly how to define the high-risk population that will benefit from screening. In addition to determining precisely who should be screened, there are matters of cost, radiation exposure, and false positives—not to mention the sensitive politics and social perceptions about lung cancer. According to the USA Today report, 87% of lung cancer cases are caused by smoking. To phrase it gently, not everyone believes that it’s a high priority to fund research and pay for treatment for a disease that is predominantly caused by a patient’s choosing to smoke.

Setting aside that sensitive issue—if doing so were possible—the medical community needs to work out some key issues:

• determining exactly which groups of people should be screened because they likely will benefit from screening;
• learning how the additional radiation exposure of scanning factors into the equation;
• weighing the risks and benefits of the inevitable false positives and incidental findings of CT screening; and
• identifying how much this will add to healthcare costs (or reduce them if earlier treatment proves to cost less) and who will shoulder those costs.

Last December’s uproar over the U.S. Preventive Services Task Force (USPSTF) mammography guidelines illustrates how data, advocacy, economics, and politics can combine to give a seemingly routine update a life of its own. Don’t expect the lung cancer screening debate to be that volatile. Whatever guidelines and recommendations may come out of the NLCST would be the first in this country. (Approximately 7 million people were screened in Japan in 2005, some with chest x-ray and others with CT, according to a study by Tomio Nakayam et al.)

“Right now, no medical groups endorse screening for lung cancer,”American Cancer Society chief medical officer Otis Brawley, MD, told USA Today.  “The best advice we can give is to encourage people to have conversations with their doctors about whether lung cancer screening is right for them.”

But screening advocates are already running with these study results that support their position. Interviewed by The New York Times, Laurie Fenton, president of the Lung Cancer Alliance, said, “The challenge now shifts from proving the efficacy of the method to developing the proper quality standards, infrastructure, and guidelines to bring this needed benefit to those at high risk for the disease—now.”

In the same article, Peter B. Bach, MD, a pulmonologist at Memorial Sloan-Kettering Cancer Center in New York, pointed out that people should not “rush out and get a CT scan yet” because the parameters of who will most benefit from screening have not been determined.

“Very soon we’ll have an answer about who should be screened and how frequently,” Bach told The Times, “but we don’t have that answer today.”

Even when we do have that answer, it will need to be deemed politically and economically acceptable before it becomes policy.

— Jim Knaub is editor of Radiology Today.