Shanghai team argues for changes in low-dose CT lung cancer screening

In China, lung cancer is the leading cause of death. Utilizing proper screening can detect and help treat the disease early, but how well does low-dose computed tomography (LDCT) screening work in a large city like Shanghai?

A team of researchers published initial baseline lung cancer screening results with LDCT conducted in more than 14,000 patients in Shanghai online Dec. 14 in Academic Radiology. All patients were older than 35 and completed questionnaires regarding 13 risk factors for lung cancer between September 2014 to 2016.

“The ultimate goal of this multicenter screening program is to build the high-risk population model and set the positive result definition suitable for the population in Shanghai,” wrote Li Fan, MD, of Changzheng Hospital, Second Military Medical University in Shanghai, China, and colleagues. “At present, it was to report the initial baseline LDCT screening results of lung cancer in seven medical centers.”

The positive detection rate—defined as any size and density nodule— was nearly 30 percent, while the incidental detection rate of cancer was 1.23 percent.

Additional findings from the study are as follows:

  • The incidental detection rate of stage I lung cancer was slightly less than 1 percent.
  • The proportion of lung cancer in lung nodules and stage I lung cancer was 3.5 percent and 81 percent, respectively.
  • Nearly 75 percent of lung nodules measured less than five millimeters (mm), while 94 percent of lung cancers were larger than five mm.
  • The ratio of non-solid nodule, part-solid and solid nodule in lung cancer was 53 percent, 32 percent and 15 percent, respectively.

Fan and colleagues wrote that if they had set the cutoff for positive non-calcified nodules at less than five mm, the positive detection rate would have dropped to nearly 8 percent and the proportion of lung cancer in those nodules would have been 16 percent.

“Therefore, by setting 5 mm as positive threshold, the proportion of lung cancer in the positive nodules would be increased, the follow-up CT scan would be reduced, and the screening benefit would be improved,” the authors wrote.