Patients with primary lung cancer detected using low-dose computed tomography (CT) screening may be at reduced risk for developing brain metastases after diagnosis, according to a study published in the Journal of Thoracic Oncology.
The researchers, led by Summer Han, PhD, of Stanford University School of Medicine in Palo Alto, California, used the National Lung Screening Trial (NLST) data to identify 1,502 participants who were diagnosed with lung cancer between 2002 to 2009 and have follow-up data for brain metastases.
Study Details
Of the 1,502 participants, 41.4% had lung cancer detected through low-dose CT screening vs 58.6% detected through other methods (ie, chest radiograph or incidental detection). Patients whose lung cancer was detected with low-dose CT screening had a significantly lower 3-year incidence of brain metastases (6.5%) vs those whose lung cancer was detected via other methods (11.9%), with a cause-specific hazard ratio (HR) of 0.53 (P = .001), adjusting for age at lung cancer diagnosis, stage, histology, and smoking status. This significant reduction in brain metastases risk among patients with lung cancer detected through low-dose CT screening persisted in subgroups of participants with early-stage primary lung cancer (HR = 0.47, P = .002) and those who underwent surgery (HR = 0.37, P = .001).
To investigate potential explanations for an association between brain metastases risk and lung cancer detected by low-dose CT screening, the researchers explored low-dose CT imaging data using a subset of patients (n = 552) who were randomly assigned to the low-dose CT arm and had imaging data available. The researchers then compared the characteristics of the nodules detected via low-dose CT screening vs those missed by low-dose CT screening among the patients who were interval detected in the low-dose CT screening arm.
Further Investigation Needed
Given the observed high rate of brain metastases among patients with lung cancer in stage I in NLST (32.4%), the research group further evaluated and compared the characteristics of the nodules of the patients who developed brain metastases (n = 12) vs those who did not develop brain metastases (n = 350) within the patients whose lung cancer was detected in stage I via low-dose CT screening (n = 362).
“This reduction in risk for brain metastases among low-dose CT screen-detected lung cancer—which persisted in subgroup analyses of patients with early-stage lung cancer and those who underwent surgery for lung cancer—may not be fully explained by stage shift nor curative treatment for primary lung cancer,” said Dr. Han. “The reduction in brain metastases risk may be because of a potentially different tumor biology of the tumors detected by low-dose CT screening that are less aggressive and slow growing, which needs to be confirmed by further investigation.”
“To the best of our knowledge, our study presents the first effort investigating the potential impact of low-dose CT lung screening on subsequent risk of metastasis,” said Dr. Han. She pointed out that using the NLST data with a long follow-up period provided sufficient time to observe the development of brain metastases.
Dr. Han is the corresponding author of the Journal of Thoracic Oncology study.
Disclosure: For full disclosures of the study authors, visit www.jto.org.
