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Annual low-dose CT screening for lung cancer is appropriate for older smokers and can be recommended for those who meet certain criteria, according to a new guideline from the American Cancer Society.

The weight of the evidence, particularly the results of the National Lung Screening Trial (NLST), favors screening for patients ages 55 to 74 who have at least a 30-pack-year smoking history and still smoke or have quit within the last 15 years, according to the guideline.

But screening should be done at a facility experienced in lung cancer screening, and clinicians need to have a detailed conversation with patients about the risks, benefits, and limitations of screening, making them aware of the risk of false-positives and the likely need for additional invasive testing.

"We're placing a strong impetus on the importance of individuals having conversations with their doctors," Robert Smith, PhD, director of cancer screening at the ACS and professor of epidemiology at Emory University, told MedPage Today.

The guidance was published online in CA: A Cancer Journal for Clinicians. An earlier review of evidence upon which the guidance is based was done in conjunction with several other groups, including the American College of Chest Physicians, the American Society of Clinical Oncology, and the National Comprehensive Cancer Network.

Many of those groups have issued their own recommendations based on the same evidence review, and are thus largely the same as the one now being issued by the ACS.

The NLST found a 20% reduction in lung cancer death for high-risk patients who had annual screening with low-dose CT compared with screening chest x-rays. In combination with previous trials -- the earlier evidence review included eight trials, three of which reported mortality -- cancer experts have come to the conclusion that there's "sufficient evidence to support screening."

Among the benefits that should be discussed with patients prior to screening are the mortality reduction, but it should also be noted that screening won't detect all lung cancers and not all patients who have a lesion detected on CT will escape death from lung cancer, Smith and colleagues wrote.

Harms include the fact that there is a "significant" chance of false-positive results, which requires additional testing and sometimes an invasive procedure, and can cause anxiety. There's also exposure to radiation from repeated tests, they noted.

The screening should be done at a facility that has "a multidisciplinary team skilled in the evaluation, diagnosis, and treatment of abnormal lung lesions" -- or at a high-volume center if such a program isn't available, according to the guidelines.

Smith noted that there are several areas where knowledge gaps exist, including the question of whether screening can be extended to a broader group of individuals based on different smoking exposure and other risk factors.

"Ultimately, they may be brought into the recommendations, but for that we need more data," Smith said.

He also said the current interval of annual screening may be changed in the future if the evidence shows a change would be appropriate.

Smith said several private insurers have agreed to cover lung cancer screens but he did not have a detailed list. The federal government could approve Medicare and Medicaid coverage for the screening, but it's likely any decision would wait for recommendations from the U.S. Preventive Services Task Force (USPSTF), he added.

There is no deadline for that decision, and it's unclear how the USPSTF would rule, although earlier studies have shown lung screening to be cost-effective.

"Clinicians who decide to offer screening bear the responsibility of helping patients determine if they will have to pay for the initial test themselves and to help the patient know how much they will have to pay," Smith and colleagues wrote in the guidelines.

In a statement, the American College of Radiology said "screening is appropriate when performed in the context of careful patient selection and follow-up."

"We urge patience and support while the guidelines and standards infrastructure to create a safe, sustainable, and effective lung cancer screening program are created and put in place."

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