Lung cancers detected after initial screenings have better survival than patients who have negative results at baseline and later test positive, according to a study published in Plos One.
For their study, the researchers used data taken from the National Lung Screening Trial (NSLT), which compared low-dose helical computed tomography (CT) and standard chest radiography (CXR) for three annual scans at baseline, one year, and two years. That trial found a 20% reduction in lung cancer mortality for CT compared with CXR. However, it did not look at how survival differed among patients who had positive results at baseline or at either of the 2 scans in subsequent years.
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Therefore, using data from the NLST trial, researchers led by Matthew B Schabath, PhD, H Lee Moffitt Cancer Center and Research Institute (Tampa, FL), assed how survival differed among patients with positive results at baseline (n = 270), at a scheduled screening (196), or a lung cancer diagnosis in-between baseline and one of the scheduled scans (44).
Kaplan-Meier survival analyses were used to calculate 5-year survival rates and compare differences in progression-free survival and overall survival between the groups. Overall, patients diagnosed between baseline and scheduled appointments had the highest rate of death (79.6%), which was significantly higher than those diagnosed after baseline or scheduled scans. Patients who had positive results at baseline that were not associated with cancer, but later diagnosed as lung cancer after positive results at scheduled 12- or 24-month scans had the highest 5-year, overall, and progression-free survival rates.
“…the main finding of this report is that lung cancer patients who develop a de novo nodule that determined to be cancerous (i.e., at least one negative CT screen prior to cancer diagnosis) had poorer survival outcomes compared to patients who had at least one positive screen prior to cancer diagnosis,” authors of the study wrote. “As such, the observation that de novo screen-detected are associated with poorer survival could be attributed to faster growing, more aggressive cancers that arose from a lung environment previously lacking focal abnormalities.”
They concluded that patients with lung cancer diagnosed between baseline and scheduled screenings may have more aggressive disease than those diagnosed after positive results at baseline, or those diagnosed after consistently positive prior screenings. More research is needed to determine whether these findings are consistent across multiple screening trails and how they can be used to inform treatment decision-making.
