AIM: Dueling editorials debate pros, cons of CT lung cancer screening

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A 72-year-old man presented for evaluation of progressive dyspnea and cough. He reported smoking one to two packs of cigarettes a day since age 15.  CT of his chest revealed bullous emphysema (bottom arrow), a tumor involving the middle lobe of the right lung (top arrow), and a pack of cigarettes in his shirt-pocket (asterisk). Source: N Engl J Med 2006; 354:397.

To screen for lung cancer, or not to screen? That is the question that referring clinicians across the country face in the wake of the National Lung Screening Trial (NLST). While radiologists may be ideally situated to help physicians wade through the nuances of the question, a group of clinicians debated the question in two articles published online Sept. 5 in Annals of Internal Medicine.

The hypothetical case considered a 62-year-old asymptomatic former smoker with a 30-year pack history who inquired about the appropriateness of CT screening.

Gerard A. Silvestri, MD, of Medical University of South Carolina in Charleston, wrote, “Recommending adoption of lung cancer screening in general practice is premature.”

Silvestri cited several reasons for his assertion. These are:

  • Reductions in death with screening are not as readily achievable as they appear;
  • Potential harms due to the diagnostic workup of false- and true-positive findings are real; and
  • NLST results do not demonstrate that the benefits of screening outweigh the harms.

Meanwhile, James R. Jett, MD, from the department of medicine at National Jewish Health in Denver, and David E. Midthun, MD, from the department of internal medicine at Mayo Clinic in Rochester, Minn., suggested that physicians should recommend CT screening to patients who fit the high-risk profile defined in the NLST, which is a departure from current recommendations.

The NLST defined high-risk candidates as current and former smokers ages 55 to 74 years, with a smoking history of at least 30 pack years.

Jett and Midthun issued a yes to screening for the high-risk hypothetical patient, with a caveat. The physicians would outline the potential risks, limitations and benefits of screening prior to the exam and strongly recommend a smoking cessation consultation prior to the CT study for any candidate who currently smoked.

The physicians supported their recommendation with lung cancer mortality data. “Only 15 percent of patients with lung cancer in the U.S. are diagnosed with early-stage (Stage I or II) disease, which is usually discovered incidentally on chest imaging studies done for other reasons.” Early-stage five-year survival is 50 percent, whereas late stage survival drops to 4 percent.

NLST results, wrote Jett and Midthun, indicate that CT screening can shift the diagnosis from advanced to early-stage disease, and thus offer an opportunity for curative treatment. The 20 percent mortality reduction demonstrated in NLST “is arguably the single greatest advance in decreasing lung cancer deaths ever reported, with the possible exception of smoking cessation.”

The authors linked screening and smoking cessation, noting that screening provides a “teachable moment,” a point reinforced by the one-year quit rate of 12 to 20 percent among smokers in screening trials vs. the 4 percent background quit rate among smokers.

Jett and Midthun advocated annual screening for such patients for three to five years and offered that new data to guide the length and frequency of screening may be available in that time frame.

Another future development that could steer the decision-making process is a lung cancer prediction algorithm that goes beyond standard factors such as age, family history of lung cancer, smoking status and history of chronic obstructive pulmonary disease. Future models may take into account genetic susceptibility variants and measured pulmonary function data.

The physicians concluded, “The positive trial results strongly advocate that physicians discuss CT screening with patients who fit the risk profile of the NLST. Screening should be done when desired by an informed patient only in a center with expertise in interpreting imaging studies, evaluating lung nodules and diagnosing and treating lung cancer.”