Guidelines Now Available for CT Lung Cancer Screening

Roxanne Nelson

May 20, 2012

May 20, 2012 — Guidelines for lung cancer screening with computed tomography (CT) are now available to clinicians.

They were developed by the American College of Chest Physicians (ACCP) and the American Society for Clinical Oncology (ASCO), and endorsed by the American Thoracic Society (ATS). They were published online May 20 in JAMA.

The guidelines recommend annual screening with low-dose CT for smokers and former smokers 55 to 74 years of age who have smoked for 30 pack-years or more, and who either continue to smoke or who have quit within the past 15 years (grade 2B recommendation).

Screening is not endorsed for people who have accumulated fewer than 30 pack-years of smoking, are either younger than 55 years or older than 74 years, and have not smoked for more than 15 years. Screening is not recommended for people with severe comorbidities that preclude potentially curative treatment and/or limit life expectancy (grade 2C recommendation).

"We found that CT screening has the potential to reduce lung cancer deaths in some smokers and former smokers when used appropriately, but there are many unanswered questions about its risks and whether it will work as well in clinical practice as it has in carefully conducted trials," said Peter B. Bach, MD, MAPP, chair of the expert panel that conducted the review and wrote the practice guidelines.

"We have gathered what is known to date and summarized it, and encourage physicians, patients, and policy makers to consider the guidelines and the evidence on which they are based," Dr. Bach said in a statement.

Based Primarily on the NLST

The guidelines were developed after a systematic review of the evidence on the benefits and harms of lung cancer screening with low-dose CT scanning. This review was a collaborative initiative of the ACCP, ASCO, the American Cancer Society, and the National Comprehensive Cancer Network, with input from the ATS.

The evidence for the recommendations was provided by 3 randomized trials on the effect of CT scanning on lung cancer mortality; among those, the National Lung Screening Trial (NLST) offered the most data.

As previously reported by Medscape Medical News, the landmark NLST found a 20% reduction in deaths from lung cancer among current and former heavy smokers screened with helical low-dose CT, compared with those screened with chest radiograph.

In that trial of 53,454 participants, there were 354 lung cancer deaths among those who underwent CT screening and 442 among those who underwent chest radiograph (a 20% reduction). For lung-cancer-specific mortality, there were fewer events per 100,000 person-years for CT scanning than for control subjects (274 vs 309; relative risk, 0.80; P = .004).

The benefits, in addition to decreased mortality, include improved quality of life, through a reduction in disease-related morbidity and a reduction in anxiety and psychosocial burden.

The 2 smaller randomized clinical trials examined in the review did not show a survival benefit.

However, there are associated risks with CT screening. These include the "futile" detection of small aggressive tumors or indolent disease, complications from diagnostic work-up (low in NLST, at a rate of 1.4%), false-positive results, radiation exposure, and cost.

Additional Recommendations

In their guidelines, the authors emphasize that screening should only be conducted in centers capable of the multidisciplinary, coordinated, and comprehensive care necessary for the screening, image interpretation, and management of findings.

Patient counseling should include a "complete description of potential benefits and harms," so that the individual can make an informed decision.

The authors also point out that a number of questions can be answered if screened people are entered into a registry. These registries would be able to capture data on follow-up testing, radiation exposure, patient experience, and smoking behavior.

Finally, the authors emphasize that screening is not a substitute for smoking cessation; the single-most important thing that people can do to prevent lung cancer is not to smoke.

"This is a technology with benefits we will only fully realize with appropriate use and infrastructure," said Dr. Bach. "We conclude that establishing a registry that records each patient's experience could help us develop a quality measurement system, similar to mammography screening, that could maximize the benefits and minimize the harm for individuals who undergo screening."

Several of the coauthors have report conflicts of interest, as noted in the paper.

JAMA. Published online May 20, 2012. Abstract