Negative Lung CT Could Lengthen Follow-Up For High-Risk Individuals

March 27, 2016
Leah Lawrence
Leah Lawrence

People at high-risk for lung cancer with a clean annual low-dose CT scan had a lower incidence of lung cancer and a lower risk of dying from lung cancer compared with all high-risk participants undergoing screening.

People at high risk for lung cancer with a clean annual low-dose CT scan had a lower incidence of lung cancer and a lower risk of dying from lung cancer compared with all high-risk participants undergoing screening, according to the results of a study published in Lancet Oncology.

Based on these results, Edward F. Patz, Jr, MD, of Duke University Medical Center in Durham, North Carolina, and colleagues wrote that it might be warranted to lengthen the interval between screenings for these patients.

“These data not only question the necessity for annual screens following a negative prevalence screen, but also suggest that annual screens after subsequent negative low-dose CT screens might not be needed; no clear biological rationale underlies the selection of yearly examinations,” Patz and colleagues wrote.

In an editorial that accompanied the article, John K. Field, MA, PhD, of University of Liverpool, United Kingdom, and Stephen W. Duffy, BSc, MSc, of Queen Mary University, United Kingdom, wrote that although the US Preventive Services Task Force recommended annual CT screening in high-risk individuals aged 55 to 80 years, the healthcare community “should consider the potential psychosocial harms, long-term accumulation of radiation exposure, and cost of annual screening over 25 years.”

“Lung cancer screening is still in its infancy, with only the USA committed to take it forward so far, thus we still have the opportunity to consider who needs annual screening and who could have much less frequent scans,” wrote Field and Duffy. “Once annual screening is embedded into a national policy, reducing the frequency of screening will be much more difficult.”

Patz and colleagues analyzed data taken from the National Lung Screening Trial, which compared three annual CT scans with three annual chest radiographs for the detection of lung cancer in high-risk individuals. Participants (n = 26,231) were aged 55 to 74 years and had at least a 30 pack-year history of smoking, or had quit smoking within the past 15 years.

Of the cohort, 19,066 participants had a negative initial CT screen. These participants had significantly lower incidence of lung cancer compared with the full population of 26,231 participants (371.88 vs 661.23 per 100,000 person-years). In addition, individuals with a negative screen were also less likely to die of lung cancer, with a lung cancer–related mortality of 185.82 compared with 277.20 per 100,000 person-years.

Lung cancer was detected in 1.0% of all participants at the initial screen, whereas, at a second screen it was detected in only 0.34% of participants who were negative upon their initial screen. According to the researchers, if this second screen had not been done, 28 additional participants in the negative group would have died from lung cancer over the course of the trial.

“Annual low-dose CT screening detects some lung cancers at an earlier, more treatable stage than no screening at all or annual chest radiograph screening, and will improve outcomes for select patients,” wrote the researchers. “However, the magnitude of such an endeavor must be weighed against the risks and costs; resources are not unlimited and society should decide how to implement a responsible screening program based on evidence-based data.”